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Catalyst: A computer-aided teaching tool for stayed and suspended systems

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Catalyst: A computer-aided teaching tool for stayed and suspended systems

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Content CATALYST: A COMPUTER AIDED TEACHING TOOL FOR STAYED AND SUSPENDED SYSTEMS by Gautam Ramchandra Shenoy A Thesis Presented to the FACULTY OF THE SCHOOL OF ARCHITECTURE UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree MASTER OF BUILDING SCIENCE August 2003 Copyright 2003 Gautam Ramchandra Shenoy Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 1417941 INFORMATION TO USERS The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. ® UMI UMI Microform 1417941 Copyright 2004 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UNIVERSITY OF SOUTHERN CALIFORNIA THE GRADUATE SCHOOL UNIVERSITY PARK LOS ANGELES, CALIFORNIA 90089-1695 This thesis, written by ^AUTAM S ttttiO Y under the direction o f h (5 thesis committee, and approved by all its members, has been presented to and accepted by the Director o f Graduate and Professional Programs, in partial fulfillment o f the requirements fo r the degree o f M ASTEfl OF B v\jt 3>i"i?2[~x s c 1 E- \ Director Thesis Committee Chair Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ACKNOWLEDGEMENTS I take this opportunity to express my heartfelt thanks to Dr. Goetz Schierle Dr. Doug Noble Dr. Jeff Guh Professor Nitin Kale Professor Marc Schiler Professor Karen Kensek My parents Ramchandra Shenoy and Bhagirathi Shenoy My Aunt Mohini K Shenoy and my uncle M L Prabhakar Htegde Dr. B.A. Sbenoi and Mrs. Suntan Shertoi Everyone in Mulki A S ! my friends at USC Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS ACKNOWLEDGEMENTS ii LIST OF FIGURES ix ABSTRACT xiv 1. Introduction to the Problem 1 1.1 Introduction to Structures 1 1.2 Evolution of architectural design 1 1.3 Examples of how systems work 2 1.4 Structures in School 4 1.5 Development Stage of the application 4 1.6 Navigation in the application 5 2. Methodology and Plan of Approach 6 2.1 Introduction to the research method 6 2.2 Outline off Tasks 6 2.3 Detailed Description of Tasks 7 2.3.1 Background Information 7 2.3.2 Theory and Precedents 8 2.3.3 Information Disseminated 9 2.4 Alternative Method or Approach 12 2.5 Operating System and Author ware 17 2.6 Secondary Multimedia Packages 19 2.7 Summary 21 3. Teaching Tools in the Real World 22 3.1 General Background 22 3.2 ‘COBALT’, an Example 23 3.3 Contextual Relevance 24 3.4 Intelligent Tutoring Systems 26 3.5 Ms.Lindquist, (Domain Theory Example) 27 3.6 Common Problems in the Learning Process 28 3.7 The Domain Theory 31 3.7.1 The Domain Theory in Structures 31 3.7.2 Testing the Domain 32 3.7.3 Testing and Determining C-lets 33 3.8 Summary 34 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. iv 4. Fundamentals of Structures 36 4.1 Introduction 36 4.2 Terminology 37 4.2.1 Equilibrium and Force 37 4.2.2 Tension and Compression 38 4.2.3 Bending and Shear 40 4.2.4 Span 41 4.2.5 Depth 41 4.2.6 Loads 42 4.3 Glossary 43 5. Light Weight Structures and Suspended Structures 47 5.1 Introduction 47 5.2 Building Investigation Project 48 5.2.1 Design Issues 49 5.2.2 Factors Considered for Recording Data 50 5.3 Cable Stayed Structures and Suspended Structures 53 5.3.1 Salient Features 55 5.3.2 Synergy 55 5.3.3 Stability and Stiffness 56 5.4.4 Suspension Structures 58 5.5 Components of a System 58 6. Strands and Wire Ropes 62 6.1 Strand 62 6.2 Wire Rope 63 6.3 Prestretching Wire Rope and Strand 64 6.4 Reasons for Prestretching 64 6.5 Removal of Prestretch 65 6.6 Strands vs. Ropes 66 6.7 Technical Details 66 7. Concepts of Suspended Structures 68 7.1 The Components 68 7.2 Problems in Buildings 70 7.3 Stabilizing Factors 70 7.4 Lability or the Tendency to Move 70 7.4.1 Non-destructive Movements 71 7.4.2 Potentially Destructive Movements 72 7.4.3 Types of Exciting Forces 72 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. V 7.5 Damping 73 7.8 Design Considerations 74 8. Concepts of Stayed Structures 76 8.1 The Basics 76 8.2 Learning from Bridges as examples 78 8.3 Radial and Harp Systems 79 9. ASCE Guidelines for Cable Structures 82 9.1 Design Loadings 82 9.2 Load Combinations 82 9.3 Cable Strength 83 9.4 Fitting Reduction Factor 83 9.5 Elevated Temperature Effect 83 9.6 Fatigue Effect 83 9.7 End fittings 84 9.8 General Considerations for Structural Analysis 84 9.9 Vibrations 84 9.10 Deflections 84 9.11 Cable Materials 85 9.12 Erection Analysis 86 9.13 Prestretching 86 9.14 Miscellaneous Considerations 86 10. Differentiating Stayed and Suspended Structures 88 10.1 Introduction 88 10.2 Definitions 88 10.3 Differentiation 91 10.4 Different Profiles of Funiculars 94 10.5 Suspension Roofs Lean Back to Resist Lateral Thrust 95 10.6 Force vs. sag/span ratio 96 11. Graphic Vector Analysis Method 97 11.1 Introduction to vectors 97 11.2 Examples of Analysis 98 11.3 Component Vectors 103 11.4 Numeric Vector Analysis Method 105 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. v i 12. Case Study: Renault Parts Distribution Center, Swindon, UK 108 12.1 Design Approach 108 12.2 Functional Requirements 109 12.3 Structural Concept and Analysis 109 12.4 Structural Form 111 12.5 Connections 113 12.6 Construction 116 13. Case Study: National Athletics Stadium, Canberra, Australia 117 13.1 Introduction 117 13.2 Alternatives 117 13.3 Final Solution 118 13.4 Primary Structural System 119 13.5 Secondary Structural System 122 13.6 Cable Stayed Structure 123 13.7 Roof Frame 125 13.8 Tension cables 125 13.9 Footings 126 14. Inmos Microchip Factory, New Port, South Wales 127 14.1 Introduction 127 14.2 Chronology 128 14.3 Background 129 14.4 Structure 130 15. Case Study Examples in Suspended Systems 133 15.1 Messehalle 26 in Hanover, Germany 133 15.2 Messehalle 9 in Hanover, Germany 135 15.3 JAT Hangar, Airport of Belgrade, Serbia, Yugoslavia 138 15.4 MOngersdorfer Stadion, Cologne, North Rhine-Westphalia (Germany) 141 15.5 David L. Lawrence Convention Center, Pittsburgh, Pennsylvania 144 15.6 Glass Canopy for a Light Rail Station (Stadtbahnhaltestelfe), Heiibronn, Germany 147 15.7 Golden Gate Bridge, San Francisco 150 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. vii 16. Case Study Examples in Stayed Systems 153 16.1 McCormick Place Exhibition Center, Chicago, iiiinois (USA) 153 16.2 Hillsboro Stadium, Hillsboro, Oregon (USA) 156 16.3 Toyota City Stadium City of Toyota, Aichi, Japan 159 16.4 Train Station "La Plaine-Stade de France", Saint Denis (France) 162 17. Compiling the Disc 166 17.1 Introduction to the contents 166 17.2 Designing and Authoring the Navigator 166 17.3 The Graphical User Interface (Phase One) 169 17.4 The Navigation Loop 170 17.5 The Graphical User Interface (Phase Two) 173 17.5 The Graphical User Interface (Phase Three) 175 18. The Components and Disc Structure 178 18.1 Introduction 178 18.2 The File formats imported 178 18.3 Disc Structure 184 19. Packaging the Disc 195 19.1 Introduction 195 19.2 The Name of the tool: Process and Conclusion 195 19.3 The Logo 196 19.4 The Compact Disc Jewel Case 197 20. User’s Manual 198 20.1 introduction 198 20.2 Overview of the Application 198 20.3 Minimum System Requirements 199 20.4 Getting Started 200 20.5 Parts of the Graphical User Interface 204 20.6 Navigation Buttons: type and function 207 20.7 Viewing Movies: Controls and Video 210 20.8 The Interactive 3D Models 211 20.9 Concluding Remarks 214 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. v iii 21. Next Level of Iterations 215 21.1 Introduction 215 21.2 The First Domain: Systems to be studied 215 21.3 The Second Domain: Embedding New Applications 217 21.4 The Third Domain: Technical Additions (Multimedia) 219 21.5 Conclusion 221 Glossary 223 Bibliography (Books) 230 Bibliography (Internet) 232 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ix List of Figures Figure 2-1: Flowchart: Main Menu bifurcation 14 Figure 2-2: Flowchart: Classification of Study 15 Figure 3-1: Typical Graphic User Interface for teaching tools 30 Figure 3-2: Process of identifying user expertise level 33 Figure 4-1: Equilibrium and Force 37 Figure 4-2: Tension and Compression 39 Figure 4-3: Bending and Shear 40 Figure 4-4: Span and Beam depth 41 Figure 4-5: Typology of Loads 43 Figure 4-6: Simple Strand 46 Figure 4-7: Simple Wire-rope 46 Figure 4-8: Helical Strand 46 Figure 4-9: Helical Wire-rope 46 Figure 5-1: Components of a Light Weight Structure 51 Figure 5-2: Typical Data Entry Sheet 52 Figure 5-3: A stayed and suspended bridge 53 Figure 5-4: Distinguishing Features 54 Figure 5-5: An Anchorage 59 Figure 5-6: Typical Components of a Suspension Bridge 61 Figure 6-1: Strand cross section 62 Figure 6-2: Six strand Wire-rope cross section 63 Figure 7-1: A Cable Suspended Bridge 69 Figure 7-2: Strand cross section 74 Figure 7-3: Wire-rope cross section 74 Figure 8-1: Deck and Stay cables 76 Figure 8-2: A single bay of a Stayed System 77 Figure 8-3: View of different Towers from the deck in cross section 78 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. X Figure 8-5: A typical bay of the Harp system 80 Figure 8-4: A typical bay of the Radial system 81 Figure 9-1: Cable Materials Specifications 85 Figure 10-1: A cable suspended bridge 89 Figure 10-2: A cable stayed system 90 Figure 10-3: Freely Suspended Cable 90 Figure 10-4: Distinguishing Features 91 Figure 10-5: A suspension and stayed bridge 92 Figure 10-8: A Stayed System (Harp) 93 Figure 10-7: Changing Profile of a freely suspended cable for different load locations 93 Figure 10-8: Profiles of funiculars 94 Figure 10-9: Piers at Dulles Airport, Chantilly 95 Figure 10-10: Force vectors based on funicular profiles 96 Figure 11-1: A simple vector 97 Figure 11-2: Finding an Equifibrant for two vectors 99 Figure 11-3: Finding an Equifibrant for two vectors 100 Figure 11-4: Finding the Resultant and Equilibrant for three vectors 101 Figure 11 -5: Finding an Equilibrant for three vectors 102 Figure 11-6: Finding an Equilibrant for three vectors 103 Figure 11-7: Component Vectors 104 Figure 11-8: Statically Indeterminate Component Vectors 105 Figure 11-9: Force Polygon for three vectors 106 Figure 12-1: Axonometric View of Renault Parts Distribution Center. 109 Figure 12-2: Axonometric View of a typical Cell Unit 112 Figure 12-3: Cross Section looking through the center 114 Figure 12-4: Computer Analysis of the structure 115 Figure 12-5: image of a typical cell unit 116 Figure 13-1: View of the National Athletics Stadium from East end 118 Figure 13-2: View of the masts 119 Figure 13-3: Cross section of the grandstand, looking at the joints 120 Figure 13-4: Site plan 121 Figure 13-5: Identifying the types of Loads 122 Figure 13-6: Dead loads 123 Figure 13-7: View of Masts from Seating Area 124 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. xi Figure 14-1: Inmos Microchip Factory 127 Figure 14-2: Prismatic Truss 128 Figure 14-3: Looking at the central spine 129 Figure 14-4: Frontal Section looking at the central spine 130 Figure 14-5: Frontal Section looking at the office areas 132 Figure 14-6: Plan of the facility 132 Figure 15-1: Messehalle 26 133 Figure 15-2: View of entrance area 134 Figure 15-3: Skylight 135 Figure 15-4: Skylight (Another view) 135 Figure 15-5: Messehalle 9 136 Figure 15-6: View of entrance area 137 Figure 15-7: JAT Hangar 139 Figure 15-8: JAT Hangar 140 Figure 15-9: Model of Mtingersdorfer Stadion, Cologne 141 Figure 15-10: Model of Mungersdorfer Stadion, Cologne 143 Figure 15-11: View of the canopy and roofing system (3D model) 144 Figure 15-12: View of Convention Center (3D rendering from proposal) 145 Figure 15-13: David L. Lawrence Convention Center 146 Figure 15-14: David L. Lawrence Convention Center (Interior view from proposal) 147 Figure 15-15: The completed canopy at Heilbronn 148 Figure 15-16: Glass nodes and pads supporting the glass 149 Figure 15-17: Support Pads 150 Figure 15-18: The Canopy 150 Figure 15-19: Golden Gate Bridge 150 Figure 15-20: Suspenders 151 Figure 15-21: The Bridge 151 Figure 16-1: McCormick Place Exhibition Center 153 Figure 16-2: View of Masts 154 Figure 16-3: View of Interiors 155 Figure 16-4: Hillsboro Stadium 156 Figure 16-5: Hillsboro Stadium 157 Figure 16-6: Mast 157 Figure 16-7: Hillsboro Stadium 158 Figure 16-8: Toyota Stadium 160 Figure 16-9: Toyota Stadium (Interior) 160 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. xii Figure 16-10: Retractable Roof (Closed) 161 Figure 16-11: Retractable Roof (Open) 161 Figure 16-12: Retractable Roof (Detail) 162 Figure 16-13: Train Station "La Raine-Stade de France”, Saint Denis 163 Figure 16-14: Train Station "La Raine-Stade de France", Saint Denis 164 Figure 16-15: A typical module 165 Figure 17-1: Navigation Buttons (Primary Loops) 167 Figure 17-2: Page Screenshot 168 Figure 17-3: Page Screenshot 168 Figure 17-4: Navigation Buttons (Secondary Loop) 168 Figure 17-5: The Navigator 169 Figure 17-6: The Complete Interface (Phase One) 170 Figure 17-7: The Basic Navigation Loop 171 Figure 17-8: The Tertiary Level Navigation Loop 172 Figure 17-9: New Location of the Navigator 173 Figure 17-10: Text box 174 Figure 17-11: Image Display Area 174 Figure 17-12: The GUI (Second Phase) 175 Figure 17-13: Top Navigation Buttons (secondary) 176 Figure 17-14: Bottom Links (tertiary) 176 Figure 17-15: The GUI (Third and Final phase) 177 Figure 18-1: Aliasing along the borders 179 Figure 18-2: Anti-aliased Image 179 Figure 18-3: Closed Socket 183 Figure 18-4: Closed Socket 183 Figure 18-5: Chapter Zero 185 Figure 18-6: Chapter One 186 Figure 18-7: Chapter Two 187 Figure 18-8: Chapter Three 188 Figure 18-9: Chapter Four 189 Figure 18-10: Chapter Five 190 Figure 18-11: Chapter Six 191 Figure 18-12: Chapter Seven 192 Figure 18-13: Chapter Eight and Nine 193 Figure 18-14: Chapter Ten, Eleven and Twelve 194 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. x iii Figure 19-1: Catalyst Logo 196 Figure 19-2: Compact Disc Jewel Case Cover 197 Figure 19-3: Compact Disc Cover 197 Figure 20-1: Table of Contents Screen 201 Figure 20-2: Table of Contents Screen (Chapter Index Page) 202 Figure 20-3: Chapter Topics Links 203 Figure 20-4: Chapter Links 203 Figure 20-5: The GUI of Catalyst 204 Figure 20-6: The Top Navigator Panel 205 Figure 20-7: The Main Navigator Panel 205 Figure 20-8: The Bottom Navigator Panel 205 Figure 20-9: The Navigation Analogy in Catalyst (parts of a book) 206 Figure 20-10: Progressive Step 207 Figure 20-11: Help and TOC buttons 207 Figure 20-12: The Main Navigator Panel 208 Figure 20-13: The Navigator Buttons 208 Figure 20-14: The current location is highlighted in blue on every page 209 Figure 20-15: The screen with a video field 211 Figure 20-16: The Playback controls 211 Figure 20-17: The Interactive 3D Model Screen 212 Figure 20-18: The Interactive 3D Model 214 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. xiv ABSTRACT The use of computers as media for teaching has been a success in many disciplines. The integration of complex theories into a program that is independent of support as the stages progress has been solved to a great level. ‘Structures’ has always been a subject which many students tend to address as uninteresting and hard to understand. The goal of the thesis is to author a CD-ROM for computer-aided teaching design of Stayed and Suspended structures. The final product will be a comprehensive CD-ROM demonstrated as a multimedia presentation containing theories that deal with span to depth ratios, the different kinds of cables, system design, vector analysis method of force/stress calculation, hints, development guidelines for the study of stayed and suspension structures. To facilitate ease of use and to maintain simple navigational control, the application has been authored using Macromedia Director. The pedagogical aspect of structures demands the need to have explanatory diagrams, examples or precedents and elaborate steps while designing or analyzing a scheme. It is desirable to illustrate each precedent with emphasis on construction process, type of system employed and analytical issues. In case of Stayed and Suspended systems, demonstrating the workability and elementary analytical issues are ideal media for comprehension. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 Chapter 1. The Problem 1.1 Introduction to Structures The design of structures primarily involves four major steps. Identifying and choosing a design scheme, proposing a system that is efficient and economical, designing the scheme and finally testing and analyses. The testing maybe carried out using a force scale model or analysis using computer programs. One of the problems students encounter in the preliminary stages is trying to identify the right scheme for its features and finalizing the scheme based on the pros and cons. The problem alludes to the fact that many aspects may not be clear regarding structural feasibility, span limits and economy based on design requirements. A simple example would be proposing a beam structure without the knowledge of span to depth ratio and the outcome on analysis would be that the beam would collapse under its own weight. Hence, such issues have to be clear before approaching a scheme and finalizing the same as most feasible. 1.2 Evolution of Architectural Design As a student of architecture, it is important to comprehend the importance of civil engineering and the many wonders it has contributed to our branch. Architecture is a branch of study where in the ‘architect’ needs a practical Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2 understanding of Structures combined with the theories of art and aesthetic sensitivity. Various systems have evolved from mainstream civil engineering that has become an integral part of the designers’ vocabulary. Schemes were developed for bridge construction, towers and iconic symbols or as instances from nature. They have evolved and become thresholds for enhanced or metamorphic edifices. An important aspect of good design is to accentuate its architectural concept and thus define its synergy. Synergy becomes inherent when the designer pays special attention to ensure that the chosen scheme is apparent in the form. 1.3 Example of how systems work One may ideally examine the instances of Bridge construction for comprehension. The evolution from simple beam and column schemes to complex schemes that utilize high strength steel cable has been well adapted in architecture. The works of Frei Otto even today inspire designers to experiment with different configurations using high strength steel. One such system, using the sag of a freely suspended cable has become the basic prototype for bridge construction as well as architecture. Cable Suspended systems which employ the ‘ funicular’ shape are almost synonymous with bridges. These have been developed further and implemented by contemporary designers in facilities varying from airports to large Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 manufacturing facilities. Furthermore, the tensile capability was explored and developed for bridge construction which was imbibed into mainstream design. Cable Stayed systems are examples of such schemes. Be it utilizing the tensile capability of a high strength steel cable or steel rods, architectural precedents crafted with this type are abundant and growing. The economy and feasibility offered by employing these schemes inspire the designer to work with systems and take them to the next level. Hence, it would be desirable for the designer to have a working knowledge of these systems. Be it the simple decision of devising the sag of a suspension system based on the span or deciding which system to choose. The emphasis on this particular typology maybe attributed to the fact that many designers tend to walk away from using such systems thinking that they are too complex to devise or uneconomical. It is important for every student to have a working knowledge of all available systems and this can be achieved by introducing the systems at the elementary level. Of course, such systems are discussed in class, but there are many cue points that are overlooked by the student. These can vary from span to depth ratios, computing metallic cross section areas, deciding tributary areas for fan type and harp type systems in stayed schemes, etc. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 1.4 Structures in Architecture School The freshman years essentially help a new student to learn about the various basic concepts, terminologies used in structures and this becomes a background. At the sophomore level, it becomes easier for the student to comprehend terms such as stress, strain, elastic and plastic deformation, etc. This level seems to be most appropriate to introduce these systems as the student can take his knowledge to the next level and develop on it. 1.5 Development Stage of the Application As a developer, one may summarize the elementary concepts of structures in a book or a computer application that would be referred by a sophomore. The latter half of the book/program would be an in-depth look at various systems of construction, their pros and cons as well as design guidelines. Today, access to a computer is widespread and simplicity in use only complements its benefits. Students tend to overlook small cue points which may be of utmost importance when choosing or analyzing a given system. If one were to develop an application that would help the student to clarify these doubts time and again, this would prove beneficial. Secondly, if this application can be developed as a tool that starts from the basics, clarifies doubts, demonstrates precedents, introduce simple calculation schemes, it becomes easier for the student to refer the same without worrying about time Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 5 or other constraints. Of course, such a tool can be developed on a website, but if the internet is inaccessible or if the bandwidth is S ow , it would contribute to delays and digression. Hence the ideal medium would be a CD-ROM which would introduce mobility and speed as an added bonus. The proposed tool will be authored on a CD-ROM which the student can carry around and use anytime. 1.6 Navigation in the Application Navigation is another important issue for multimedia presentations. Most packages available in the market today for quick presentations provide linear navigation, which means that skipping to the very top level from an intermediate level would be a laborious process. The need to establish links within each subcategory that provides complete user control is essential. One such package that is used for developing is Macromedia Director. Director is a simple but powerful tool that is used in game design, non-linear and complex presentations as well as authoring multi-level data packages with interactivity which can be completely user controlled. It is important to understand that along with simple text and pictures, the authored package has to be abundant in precedents, audio visual cues and voice-overs. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 6 Chapter 2. Methodology and Plan of Approach 2.1 Introduction to the Research Method The first step is to work towards compiling a set of topics and assembling them as a single database. This commences with the background research associated with data collection. It is important to note that such research has to start with defining simple quantities that help the designer in painting the big picture. Elementary definitions and understanding the effects of static and dynamic loading in nature, as well as the inherent stress developed within a body as a reaction to forces are some of the quantities. The ideal case is to know that every element should be in a state of equilibrium. Such, simple assumptions will then lead to defining more complex issues that govern design and analysis. 2.2 Outline of Tasks An outline of the tasks at hand follows: i. Elementary study of systems ii. Study of cables (strands and wire ropes) iii. Review case studies iv. Review design/analysis methodologies V. Review typical details Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 7 vi. Review appropriate teaching methodologies vii. Develop CD outline and sample content viii. Evaluate CD outline / content ix. Refine CD structure / content x. Test CD on undergraduate students 2.3 Detailed Description of Tasks The various tasks carried out as a part of the background research are briefly described in this section. Tasks vary from technical data collection to choosing media to author the tool for optimum applicability. 2.3.1 Background Information The collection of background data includes outlining the concepts involved in the study of structures, loading (associated typology and behavior). Additionally, factors like force, stress, strain, stability, and synergy have to be defined. The symbols or notations associated, formulas, graphics and finally empirical values need to be stated for a good understanding. The background research also involves collecting information on a typical example that forms a backbone for the study of such systems. In this case, the best example would be a good case study that is explanatory in terms of Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 8 its synergy, and thus the structural system. The second part of this introductory session would be introducing the various components involved. This is a simple break up of different kinds of cables, materials, specifications prescribed, design parameters, and clearly differentiating these components based on technical data as well as the factors that influence design. 2.3.2 Theory and Precedents The second task is to collect additional data that complement the two systems. This is best described in terms of precedents that are seen in the contemporary design and form backgrounds for further study and iterations that lead to better systems. Such a study reveals how the entire system works and why it invariably becomes a good example. Furthermore, architectural precedents which are typical to the two systems discussed also become important for better comprehension. The idea would be to introduce the user to a set of ‘preceding chapters’ within the tool that explain the systems theoretically and then clarify any doubts with the help of precedent study. The precedents studied would broadly fall into two categories. The first is bridges and the second is architectural precedents. The chapters containing Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 9 theory pertaining to the two systems would have one example of each category to explain the concepts. In addition to this, guidelines for selection of cables, standards and specifications on cross sections of strands and wire-ropes as well as fittings have to be tabulated. The analytical aspect of such systems chiefly involves examining the graphic vector analysis method to ascertain quick calculations for the forces involved in the design. This method can be used to compute the tension in cables based on horizontal and vertical reactions due to loading. It is important to learn this technique since the calculations can be carried out quickly by determining the live and dead loads of a system as well as affected tributary areas. Additionally this method can be used to analyze a given case to check if the provided cross section is feasible or design the required cross section based on allowable stress. Demonstrating this method with case study examples will be included in the complete package as a single stand alone chapter. 2.3.3 Information Disseminated The third aspect of the preliminary background research is to examine different techniques of communicating such data to the user without overburdening him/her with information. This requires structuring the data in a systematic format. The categories include elementary theory, numerical examples, precedent study, standards and guidelines concluding with or Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 10 without a quiz. Elementary theory is introduction to concepts and definitions and such concepts. The research also includes examining prevalent theories related to pedagogy, for instance the Domain Theory (Chapter 3) as well as basic examples of teaching tools available today. Such study describes a milieu and defines a structure for the categorization of information in terms of hierarchy. The final step is to layout the structured data on a platform to author the final product. The bullets below provide the preliminary structure developed during the process of data collection. Each level refers to the following chapters. LEVEL 1: Introduction • An Overview of the task at hand • What are the selection criteria that determine an appropriate building system for a given case? • What are the criteria that will be crucial in selecting Cable systems as the appropriate solution? ® What are the kinds of cable systems? • How does one select the right one for a given case? • What are the architectural applications? LEVEL 2: Introduction to Cables • What are cables? (Strands vs. wire ropes) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. • Define Stayed and Suspended systems • How is the geometry defined? • Min. and max. span limits LEVEL 3: Cable-Suspended Systems • What are suspended systems? • Types of suspended systems • What is the geometry, how does it govern the design? • More on Geometry • Case studies / Applications • Approximate analysis/design example • Computer analysis/design LEVEL 4: Cable-Stayed Systems • What are cable-stayed systems? • Types of stayed systems • What is the geometry, how does it govern the design? • More on Geometry • Case studies / Applications • Approximate analysis/design example • Computer analysis/design LEVEL 5: More Discussions (Comparative for both systems) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 12 • Design development • How does geometry affect design development? • How does geometry govern synergy with architectural objectives? • Comparison of geometry/synergy for both systems ® Numeric examples LEVEL 6: Analysis and design (both topics) ® Analysis and design • Methodology for detailing • Adapting proven details to new conditions ® Prototypes, involvement of Rapid Prototyping LEVEL 7: Details ® Display and describe fitting details • Conclusion / Iterations • Give examples using 3D prototypes 2.4 Alternative Method or Approach The other approach that can be taken is direct introduction to precedents subcategorized as examples for stayed and suspended systems. In this case all the theory will succeed the precedents so as to explain using examples only. Additionally, standards and specifications can be alluded to Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 13 with the precedents with emphasis on the predominant standard that was applicable in the given precedent. Each chapter would have the two systems and relevant examples as well as standards, building codes and audio-visual examples for additional clarity. Each chapter would have separate sections that fall into explanatory data, figures, images and architectural drawings, building codes prescribed and applicable, design details with emphasis on prototypes as well as unique fittings. Hence, at any given time the user will have the option to access a full chapter that looks at a case study, its architectural drawings, the details and specifications as well as building codes applied. One of the drawbacks is that, if a user wants to access elementary data, for instance, computing the sag of a suspension system, he/she may have to go through some additional information at the beginning. Although, the data flowchart for this method of working is a prototype for all the chapters, accessing specific information can be a laborious job. The diagram below is a simple way of showing how the flowcharts would be for the case examined above (Fig.2-1). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 14 Main Menu Stayed Systems Suspended Systems Figure 2-1: Flowchart: Main Menu bifurcation Hence, the main menu would be divided into two categories based on the two systems. Each system would have sub categories of topics dealing with details. The same is demonstrated as a prototypical flow chart below. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 15 Typical Stayed I Suspended System Chapter r Example with architectural data Figures, analysis and design parameters Data I Technical Study Precedent Study ASCE guidelines Vector Analysis Specifications Building codes Prototypes Details Figure2-2: Flowchart: Classification of Study As shown in the above flowchart, each case study will have two parts, architectural design data and technical data. The architectural drawings, form development, concepts, etc will be stated in the precedent study Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 16 section. Other technical data like cable sizing span to depth ratios, cable forces and codes will be specified in the second category. Each chapter will end with a summary that identifies key points that are unique to each example and relevant information. If this scheme is applied, one of the other issues that may cause navigational errors would occur when the user is looking for concise outlines of theory. That means, he/she would have to look at sections under different chapters to find a summary of building codes. It would be desirable to consolidate all theory specific to a system under one category so that after referring this section, the user may proceed to examine precedents that are applicable to the same. Similarly, all examples that are common to a typical system can be combined under one category. This means that the system mentioned afore may not work as suggested since it would lead to repetition. Hence, the ideal approach would be to retain the two topmost levels of systems and build subcategories under each while introducing new levels to deal with theory, examples and numerical problems separately. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 17 2.5 Operating System and Author ware Some of the queries that come to mind when one discusses teaching tools is ‘How does one author the tool? Which platform and what would be the ideal package to author?’ etc. There are several possibilities to experiment with, for deciding the platform and packages that will encompass the complete tool. Many engineers, programmers today use packages like Visual Basic, C or other such programs to write fully working programs. But for an amateur programmer a package like visual basic does not provide 3D support or audio-video plug-ins. It is possible, but the task involves working with Java 3D and programming codes in the 3D environment. Additionally, complex navigation loops can be hard to debug. Many external file formats like QuickTime, Shockwave, Flash and various audio formats would be difficult to embed within one such package. The protocols established for importing 3D objects are difficult to work with. The too! proposed here has to be a complete interactive multimedia experience and hence, the requirement to embed many different file formats arises. Additionally, internal controls for playback rewind for animations are required. Compatibility issues with different operating systems, minimum system requirements, VR plug-ins are other issues. On the other hand, a simple interface, with easy linear navigation is possible. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 18 After taking into account the above constraints, Macromedia Director was considered as the ideal authoring application which also makes it easier for the tool to be bundled onto a CD. Director is compatible with numerous file formats. Although, Director allows the authored package to be delivered on either OS’, the tool in question is limited to use on PCs. Additionally, sound, video, images and 3D models can be imported into Director for use in the package. The Director metaphor is that of a theater, where in the working space becomes the stage and all the ‘casts’ are the imported files which perform actions as ‘sprites’ over a timeline. Infinite number of loops can be established to revert or proceed as navigation tools. Shockwave 3D also allows custom 3D rendering and the author can choose to use OpenGL, Hardware or Software rendering. Advanced 3D packages like 3DS Max, Maya, and Softimage also have shockwave exporters supplied as plug-ins and hence 3D models may be exported from the modeling and animation environment to the author ware realm. Additionally Director has its own scripting language called ‘Lingo’ and the syntax is easy to learn. Lingo is very powerful and can be scripted to perform any task within the program, or even within the OS. For instance, a lingo script to reduce or increase monitor resolution can be written so that the tool runs in full-screen mode every time it is executed or viewed. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 19 Director also allows presentations to be published for the web or packaged onto a CD or DVD. The idea of authoring the tool onto a DVD is interesting but limitations like access to DVD-ROM drives was a predominant issue that seemed to put forward CD-ROMs as an affordable and accessible medium for delivery. As for the internet, high resolution videos and 3D applications can take time to stream for users with low bandwidth. The very backbone of the tool is its use of multimedia for a more convincing experience. Hence, the only other medium suitable as mentioned afore is CD-ROMS. Moreover, all CD-ROM drives today have a minimum of 2X to 12X read speeds without the occasional buffering or overrun problems, and hence CDs seem to be the best medium. The choice remains whether to use five and a half inch discs (size limitation is 650 to 700 megabytes) or three and a half inch discs (size limitation is 150 to 225 megabytes). This can only be decided at the final stage when the tool is authored, debugged and ready to be distributed. 2.6 Secondary Multimedia Packages The next important task is to determine the secondary applications that will be used in creating the various multimedia components. Before deciding the list of packages for various multimedia elements, it is important to identify the kind of media that will be used to impart information. These would be audio, images, video, three dimensional elements, and animation. Among the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 20 various applications available to record, edit and process sound, Sonic Foundry ‘Soundforge’ offers a simple yet powerful platform which is easy to use, yet effective. Soundforge offers mono, stereo, single and multiple channel sound editing as well as additional effects and plug-ins to record and edit media. One has the option to process a sound file that would be compatible with various operating systems, various formats like *.wav, *.mp3, *.mp2, *.aiff, as well *.rm and *ram. Adobe Premiere is a video-editing and packaging software that works with various formats like mpeg, mpg and avi. Premiere functions on the concept of a time line with channels provided for synchronizing audio and video with the added bonus of transitional effects. Avi formats exported from 3d animation packages can be imported into Premiere and processed into professional quality videos for presentations. Premiere also offers the option to work with different codecs (coder-decoders) to make files playable on different media players. Premiere also has the option to make files stream- able so that a video can be streamed over the internet depending on bandwidth constraints. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 21 Aiiaswavefront Maya and 3D Studio Max are predominantly the most employed 3D development and animation programs available today. Each package has its benefits, for instance Maya is used more for animation in movies and Max is used by architects as well as movie makers. Both programs have extremely powerful mapping capabilities so as to make models designed in a 3D environment very lifelike. Also, walkthroughs object VR (virtual reality) are well supported by both packages and many plug-ins are available for exporting media between different platforms. Additionally complex environments can be created and set up using MEL scripts (Maya Embedded Language) for various requirements. As mentioned earlier, such processed media can be imported into Premiere and packaged to deliver a professional presentation. 2.7 Summary To summarize, the initiative to make the tool a multimedia title is an effort to ensure that the process of learning becomes a rich and wholesome experience with emphasis on complete comprehension of the technical aspects as well as aesthetic sensitivity. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 22 Chapter 3. Teaching Tools in the Real World This chapter examines the teaching tools available today for different disciplines. The application varies from everyday software based tutoring to hi-tech flight simulation systems. Examples of tutoring systems for math and other applications are briefly examined. Next, generic GUIs (graphic user interface) are observed and emphasis is given to navigation as well as content management. Finally the Domain theory is explained along with its implications in the context of this dissertation. 3.1 General Background Application of computers in pedagogy has proven to be beneficial in enhancing the learning experience. Be this in the form of Computer Aided Teaching, Internet based teaching applications or interactive web consoles that guide the user in a systematic fashion to nourish interests. Today, any individual can pick up a CD-ROM off the shelf and take lessons to perfect what he or she has had an interest to develop skills in. The integration of complex theories into a program that is independent of support (by means of human intervention) as the stages progress has been solved to a great level. For instance, a simple CD-ROM can come in handy today for an individual to learn and develop his skills in 3D Studio Max, a 3D design/ rendering/ Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 23 animation package. The CD essentially has a narration that introduces the user to the world of 3D with emphasis to Cartesian coordinates and color schemes. As the chapters progress, the user is asked to perform simple models using the program. A comparative analysis is made at the end of each session. The lessons offered are broadly classified into simple modeling, nurbs, texture mapping, rendering, lighting, and finally, complex issues like character animation. The tool has been developed such that the user completes each lesson by a follow-up exercise and finally a re-cap of commands, etc. 3.2 ‘COBALT’, an Example COBALT (Computer based learning and training system) is a web based, teaching tool that is used to train pilots in the Qatar Air force. The theory adapted is based on a tool developed by Sogitech in France to combat the constraints of providing requisite number of courses with a shortage of human resources. COBALT is a computer based training tool, combining theory and practice in an interactive environment that enables the trainee to acquire the knowledge required to fly or maintain the aircraft. Real time combat sessions, dogfights, and issues related to avionics can be simulated so that the trainee is acclimatized to such situations. This is one of the examples of highly developed training theories implemented to cater to Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 24 constraints that are difficult to meet. Another example is a web based teaching tool, the Webmonkey, developed by Lycos Networks and software professionals as a potent database for the developer. The various lessons offered are by no means ‘interactive’, but certainly provide patches of practice sessions. The reason being that most of the training sessions offered are on the assumption that at the user end, these packages are owned and are licensed copies. Also, the resources provided are tutorials based and hence the end user receives exhaustive training. 3.3 Contextual Relevance For a student of architecture, designs that are unconventional and yet, based on simple concepts, are always intriguing. With the industrial revolution came the advent of steel. The ‘iron leviathan’ was a binding factor that chugged away from city to city, nation to nation bringing the world. Exploration of man’s power, social status and confidence was manifested in buildings that grew taller and taller. Bridges spanning unbelievable lengths were connecting cities and a new era began to evolve with the construction of these marvelous structures. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 25 Cable suspended bridges proved to be the only viable solution for very long spans. Frei Otto was one of the few thinkers who took these theories and put them to effective use for buildings, based on the Raleigh Arena by Novicky I Deitrick. The theory was simple, i.e., to derive the strength from the funicular form of high strength cables or membranes, and stabilize them by anticlastic curvature or other devises. The first prefabricated cable nets were designed by Saugey / Schierle for Expo ’64. From then on suspended structures were not only synonymous with mammoth bridges but also to the human scale with use of these systems in architectural application. Stayed structures were another development where the designs depended primarily on the tensile capacity of stays to support horizontal members. As the designs developed, the concepts became more streamlined and specialization became essential. Although, today there are many structures which are good examples of such systems, learning about them can be a difficult task since many theories are interwoven to form newer ones. The need to work on the basics of these systems for any student of architecture or civil engineering is important. While there are many books that provide the necessary information; it is difficult to narrow down on a singular source. Hence, it would prove beneficial to devise a source that requires only self-study and yet is rich enough in Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 28 content to educate an individual about the basics, design, and development of these unique structures. 3.4 intelligent Tutoring Systems The proposed teaching tool will be a step by step guide and resource to acquaint the student with various issues, such as span limits, sag/span ratios, stay configurations, geometry/synergy, load conditions, etc. The tool would assist in educating the user about these structures using case studies and then move on to design, analysis and prototype development and detailing. The previous discussion pertaining to the advancement in teaching tools reinforces the issue of ‘teaching’ theories. Such a tool would assist a teacher to provide a background before a student divulges further into more complex issues based on his/her interests. Most of all, such a tool would be beneficial in helping a student start at an elementary level. With the completion he/she would have working knowledge to apply theory in design studio. Hence, the tool has to be broken down into various levels of issues tackled at different stages. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 27 3.5 Ms.Lindquist, an Example Based on the Domain Theory The next phase is to further explain how a tutoring system works and its implications, examine backgrounds of other systems and discuss the same in the context of the too!. While some of these examples may be third generation ITS’ (which require minimal human intervention), many of the salient features will be used as templates for the design of the final product. From here on, the scope of the project and the contents will be referred to as a ‘domain’ in reference to the Domain theory which will be explained further on. The first example, ‘Ms. Lindquist’ is a web based algebra tutor developed by Hefferman and Koedinger (2002). This tool is a Java based program compiled at Carnegie Mellon University and is set up remotely to teach symbolization. Symbolization is defined as the method of quantifying a real world problem (verbally presented) as an algebraic expression. The architecture of ‘Ms. Lindquist’ is devised to track common problems encountered by students and then formulate a strategy to sort them. The design primarily consists of curriculum scripts and micro-plans involving a series of questions designed to remediate particular difficulties. This logic is deduced from the example adopted by some human tutors where, instead of providing ‘supplementary hint answers’, the tutor poses a ‘hint question’. Such a problem solving technique is referred to as ‘Concrete Articulation Strategy’. Hence, in the process, the student tends to reflect on the thought process and attempt to solve the issue at hand. One of the background Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 28 requirements to achieve this is the study of common mistakes committed by students, the study of what makes a particular domain difficult. The next step would be to construct a ‘Cognitive Model’ which constitutes of theories related to how students solve problems. Additionally, it is important to observe an experienced tutor and identify the pedagogical content knowledge they have and then build a tutorial model. 3.6 Common Problems in the Learning Process In the design context of the tool, some of the basic observations from the past are that students tend to overlook the logical synthesis of why a particular calculation was executed. As a part of theoretical study a student may overlook the reasoning pertaining to why a certain condition was adopted as a part of the design and thus end up with limited knowledge of the topic in question. A good example would be the calculations related to cross section area of strands. When this area is computed, the designer must assume only 70% of the gross area as metallic since the other 30% consists of air gaps. Although a tutor may identify this point in class, it may be overlooked resulting in severe errors in calculations of chord forces. So, as the computer aided tool is designed, such requirements must be brought to the student’s attention at the required stages of discussions related to the theory of a particular case. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 29 Tutorial reasoning is thus implied and thus the tool tends to answer many of the questions. One of the issues to develop such a database is to structure these ‘hints’ in a favorable format such that at any given instance, cross referencing is not a difficult task. Many programs today have help options that contain voluminous explanations, but referring them and finding the right answer may be a laborious task. Hence, for the tool in question, such issues will be dealt with as ‘hint bubbles’, a pop up menu option (pertaining to the topic) that will be an integral part of the overall GUI (figure 2-1). In most intelligent teaching tools, a certain pattern may be identified as the system for devising the architecture (Devezic & Harrer, 2002). Such patterns are essentially used to ensure that the system may support collaborative and individual learning. For tools that are used to teach calculations and numerical exercises, a problem solver module (logic or reasoning engine) is included in the referencing. These include logic based inferences, case based reasoning, student model evaluation and other tasks associated learning and teaching activities. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 30 Pop up Help Bubble Main G UI with Contents i Contextual j Index Progress Bar with options to scroll back and forth Figure 3-1: Typical Graphic User Interface for teaching tools These engines are designed to proceed with evaluative inferences and thus, the program becomes customized for each given case. But, for teaching systems that handle more theory and explanatory modules, such engines are simpler and customization may be possible. Here it is important to note that, as a student assimilates a part of a certain theory, the module then proceeds to the next stage and nothing may be inferred. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 31 3.7 The Domain Theory This theory introduced by Samuel Messick (Wiley 2002) is used to identify boundaries and structure the construct to be assessed. The structure of the “ Content Domain” contains job analysis, task analysis, curriculum analysis and the domain theory. The theory essentially asserts a given problem to be broken down into its constituent components, distinguished by the level of expertise required to assimilate the same. The need to employ principled skill decomposition, task analysis assists in identifying and breaking down the domain expertise into its component parts. 3.7.1 The Domain Theory in Structures Consider the example of distinguishing stayed and suspended structures, since this is the principle issue that has to be understood before divulging into details for each system In case of suspension systems the roof deck is supported by the cables / suspenders that resist gravity load in pure tension, while wind uplift is resisted by dead load, anticlastic curvature, or stabilizing cables. The cable stayed deck system is in bending, supported by stays that are supported by towers. The design of these systems may be done by graphic vectors that represent magnitude and direction. To that effect, animating these actions would give a good visual cue for comprehension. Hence, the components, vectors (forces with magnitudes and directions) act Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 32 as individual components that form the big picture, the domain. Here again, one can mention that the expertise level can vary with just visual cues to factual calculations in addition to cues to deduce the components. 3.7.2 Testing the Domain The Domain theory also suggests that a work model may be constructed with a domain map that consists of “ systematically combining and recombining tasks and objectives through task analysis procedures that have been fragmented at a lower level” (Gibbons et al. 1995). This process may consist of back referencing and interplay to refine the overall model. It means that the smaller components can be modified to infer a better map and thus refine the process. The other task is to establish the dimensionality of the domain. A dimension is the ‘dimension of expertise’ which is governed by the types of activities that experts tend to engage in. For instance, in language learning, the dimensions may be reading, writing, speaking and listening. The process of discovering these dimensions may include qualitative methods (review and synthesis of existing literature) and quantitative methods (factor analysis). Work models help in doing this. In case of the tool to be designed, a study of existing literature helps in identifying the qualitative method. The various references used will have inherent levels of expertise and these become the working models. As one can deduce, the final domain map would be a Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 33 procedural one with discussions which are incremental in expertise level from the commencement of a chapter to the next stage. Factor analysis on the other hand would constitute how the levels are decided and appropriately located as the tool progresses. I Work Model (Level 1) j j Work Model (Level 3) j j ; i ▼ ▼ i— i -------1 ------- 1 ------ 1 ------- 1 — ► I High Level Of ; Expertise Work Model (Level 2) Figure 3-2: Process of identifying user expertise level (Source: Gibbons et al. 1995) 3.7.3 Testing and Determining C-lets Finally, testing and improving the domain map is preferably carried out in a ‘validity argument’ framework. In this case, where the map is actually tested, the common problems that may crop up are noted and then the map is Low Level O f Expertise Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 34 restructured. This process is technically determined by collecting a set of ‘c- iets’. C-lets (case-lets) are a set of questions or response probes scored as a whole, the entire C-let being linked to a particular difficulty or expertise level of a particular construct involved in a work model (figure 3-2). Such a process may involve complex and integrated performances (trials and errors) in order to assess the necessary substantive growth processes within a domain. Hence, the work models synthesized previously for the purpose of instructional specification are now reused as assessment specifications and one or more C-let(s) are developed for each work model and placed on a dimension. 3.8 Summary For the final product to be a good working domain and an effective one, one has to also study the humane aspect of how interaction progresses in a given case (Mavrikis 2002). This is assessed by studying how the student interacts and the emotional state manifested by facial, vocal and mouse activity. Disinterest or lack of complete comprehension can be studied from such observations and for further analysis. This system of working is used to define the DANTE (Dynamic Authoring and Tutoring Environment). The Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 35 DANTE is the final outcome after synthesis and addition of improvements to the ITS (intelligent tutoring system). To summarize, one must be aware that any tutoring system is a powerful medium that has to be constructed in a procedural fashion and this implies that its application in a real world situation is effective enough to ‘educate’. A follow up to the entire discussion would be to categorize the involved steps and thus establish the architecture of how the system functions. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 36 Chapter 4. Fundamentals of Structures 4.1 introduction A student of architecture has to have a clear understanding of the fundamentals of structures. It is important to understand what terminologies are used and what they mean (Harris and Li 1996). Differentiations between terminologies like building envelope and building structure are expanded while defining what functions a building physically performs. Other aspects to differentiate involve space enclosure, weather proofing and thermal insulation. Thirdly, structural action involving loads, spans and supports are factors that define typology. In traditional masonry buildings these functions are performed simultaneously by the wall, floor and roof elements. In framed structures including most of the masted structures these are represented by two distinct constructional systems i.e., by a space enclosing and weather protective building envelope and by the particular type of structural framework which supports it. The structural system has to resist all dead and live loads, which impinge on the building fabric and transmit them to the ground as directly as possible. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 37 4.2 Terminology Listed below are the different terms, their definitions that are used while studying structures (Harris and Li 1996). 4.2.1 Equilibrium and Force A force is defined as anything that changes or tends to change the state of rest of a body or its uniform motion in a straight line (figure 4-1). In buildings it is the external loads on the structure, plus its own weight, which induce internal reactions in the structure. net = 0 100 Units 100 U n its Equilibrium 100 Units motion or change in shape Figure 4-1: Equilibrium and Force Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 38 These forces may come in different orders of magnitude and act in different directions over small and large areas. Isaac Newton deduced that if equilibrium has to be maintained, all the originating forces must be resisted by equal and opposite reactions (figure 4-1). The internal forces can take only five different forms, namely tension, compression, bending, shear and torsion. 4.2.2 Tension and Compression Tension and compression are axial forces, which either pull apart (tension) or press towards each other (compression) in opposing directions (figure 4-2). When axial forces in straight members pass directly through the centroid of the member without causing any tendency towards bending, the forces are referred to as ‘direct’ tension and compression. Resisting these axial forces in a member involves the strength of the material in tension and compression, which may not be of the same value, and the cross-sectional area over which they act. In theory all the material in the cross section should be fully used. In practice however, this holds good for tension-loaded members. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 39 Teaslstt Com pression Figure 4-2: Tension and Compression Such members usually fail through excessive extension when the material reaches its yield point. Compression loaded members on the other hand may fail by buckling, i.e., by sideways bowing, at a stress level well below the ‘squash load’ of the material. The tendency to bow is governed by the slenderness of the member and hence initial straightness is of utmost importance. Tensile forces cause a straightening effect, even on a slender member and hence minimum volume solids tend to act as more efficient tension members. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 40 4.2.3 Bending and Shear In spanning members subject to non-axial loading, the internal force action is mainly in the form of bending and shear (simple rectangular beams, flanged beams and girders). In resisting the flexural effects of bending, the extreme fibers at the top and bottom of the beam are subjected to higher compressive and tensile stresses with zero stress at the neutral axis (figure 4-3). Additionally, non-uniform bending stress causes horizontal and vertical shear stress. Hence, additional material is required to resist bending that uses only half the cross section and is less efficient in terms of material than direct tension or compression. Consequently there is a hierarchy of load carrying efficiency with the members in direct tension being first; those in compression second, and those in bending and shear as least efficient. t v i ■ g p f Shear Figure 4-3: Bending and Shear Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 1 4.2.4 Span Span is technically important since bending moment grows with the square of the span and deflection increases with the cube of the span for point load, or to the fourth power of the span for distributed loads (figure 4-4). As span increases, simple rectangular beams reach a point at which they can no longer support their own weight and need to be strengthened. In case of tensile structures, these limits can be greatly extended because of the tensile nature of members and partly because the wiredrawn steel in cables can resist stresses up to 5.8 times as great as the rolled steel in conventional steel beams. 4.2.5 Depth Structural depth is important both in spanning members and in the system as a whole (figure 4-4). The greater the depth of a beam, the greater would be the distance of its resisting fibers from the neutral axis and therefore the - t t Figure 4-4: Span and Beam depth Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 42 better it would be at resisting bending moments, and the bending stresses in the member would be smaller. The same principle applies in tensile structures. In tensile systems such as suspension bridges, the sag or distance from the lowest point of a suspension cable to the top of the towers or masts represents the effective depth, so that as the sag is increased, the system as a whole can support heavier loads and span longer distances. 4.2.6 Loads Types and sizes of loads make up a third important factor. Over long spans the self-weight of the structure becomes critical, but also because the load/span relationships have significant effect on a structure’s efficiency (figure 4-5). The stayed system reduces the lengths of the roof member to a series of short spans for which beams or trusses can be used. The transfer of loads to the ground takes place indirectly by suspension elements, which are effectively in tension, and masts, which act in tension. Simultaneously the masted configuration increases the effective depth of the structural system as a whole while reducing the depth of the main spanning members and also the height of the building envelope. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 43 P o int Load k Uniform Load Distributee! Load Figure 4 -5 : Typology of Loads 4.3 Glossary Below is a list of technical terms for components in cable systems, with their definitions (ASCE 1997). Anchorage: A structural member at which the cable is terminated. Cable: A flexible tension member consisting of a wire strand or a multiplicity of wire strands forming a wire rope. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 44 Clamp: A cable fitting that transfers force by friction. Damper: An active or passive device attached to the cable structure that modifies the structural response to dynamic loads. Deflector: A grooved cable support used to create an angle change in the cable, also known as a saddle. Fitting: An accessory used as an attachment to, or support for, the cable or its components. Grade: Classification of cable by nominal cable strength and/or metallic composition of wire. Modulus of Elasticity: The slope of the secant to the stress strain curve between 10% of the nominal cable strength and 90% of the Prestretching force. Nominal Cable Strength: The nominal cable strength of a cable is a computed value based on the breaking strength of the individual wires and the type of cable, as given in ASTM standards. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 45 Prestressinq: Applying a tensile force to a cable at the time of its installation. Prestretchinq: Applying a tensile force to a helically twisted cable according to a predetermined program in order to remove constructional stretch in the cable. Prestretchinq Force: Tensile force applied to a cable one or more times and held for a specified duration during prestretching. Rope: A plurality of strands twisted about an axis, or about a core which may be a strand or another wire rope. Strand: A plurality of wires either parallel or helically twisted about an axis, usually about a central wire (figure 4-6 & 4-8). Termination: A device, also known as an end fitting, attached to a cable to transfer the tension in the cable to its supporting anchorage. A termination may also be a loop formed from the end of a rope. Wire: A single continuous length of steel with a circular or noncircular cross- section. Wires of circular cross section are cold drawn from rod. Wires of Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. noncircular cross-section are either cold-drawn or cold-rolled from rod (figure 4-7 & 4-9). Figure 4-7: Simple Wire-rope Figure 4-6: Simple Strand m Figure 4-8: Helical Strand Figure 4-9: Helical Wire-rope Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 47 Chapter 5. Light Weight Structures and Suspended Structures 5.1 Introduction Light weight structures include cable, membrane, pneumatic and arch grid systems. Richard Fooks (1986) of Royal Melbourne Institute of Technology further categorizes these as ‘form active’ structures that supports loads and are light and flexible in construction. ‘Form active’ structures as “non-rigid, flexible matter shaped in a certain way and secured at the fixed ends and can support itself and span space”. This structural group is one of the classifications used by Heinrich Engels (1977). The engineering of light weight includes material science, structural analysis, fabrication and construction planning. Architecture of light weight structures includes form finding, space appreciation, lighting, acoustic, and environmental design. As discussed previously, it is important for any designer of these structures to have a thorough knowledge of the structural forms integrated with an understanding of related engineering, architectural, and constructional complexities. One of the important questions Richard Fooks addresses in his paper is “How does one promote this form of construction as a feasible and important alternative to the traditional types of construction? How does one create a better awareness and understanding of light weight structural Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 48 systems?” The principal set of steps taken while studying traditional forms of construction are model making, guest lectures, design analysis. But sometimes students tend to forego the design analysis during progressive stages. The other problem is lack of understanding of technical aspects and limited awareness that tends to make a student step away from working with such structures. 5.2 Building Investigation Project One of the systems adopted at the Royal Melbourne University, developed by Professor Fooks, “Building Investigation Project” has proven to be an effective technique that helps students get acquainted with such systems. The principal elements identified by him are forms, shapes, materials, and construction process which stand as unfamiliar issues to students. Hence, some important issues are identified that are important and invariably allude to the system as a whole. This ensures that a good level of comprehension was established and the system was understood in its completeness. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 49 5.2.1 Design issues The issues are:- i. Develop skills in obtaining accurate, concise, and relevant information about light weight structures. ii. Increase understanding in terms of general technical details and planning issues. iii. Develop skills to evaluate the performance of buildings in a certain environment or a given backdrop. For instance, if one were to study an existing structure, it would be important to identify the use, why a particular system was a feasible alternative to traditional construction, what special lighting and environmental controls were required. This is particularly important since fabric structures have the capability of permitting light due to their translucent property. Other factors that may have influenced the economic viability of light weight structures, the type of fabric, type of material degradation, disadvantages, designers, builders and consultants involved. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 50 5.2.2 Factors Considered for Recording Data The following chief factors are finally listed and entered onto a data sheet. Such a data sheet provides an extensive source that defines the building in question. i. Layout Information ii. Building Form iii. Construction Materials iv. Structural System V. Construction Technique vi. Date and duration vii. Performance Assessments viii.Analysis, Form finding and Calculations ix. Construction and Structural Details x. Fire and Exit Provisions xi. Design and Consultant Details xii. Building costs Additionally for Stayed systems one can list out why the system is effective, under what conditions it was sought after to be the most feasible. Geometry of surface structures can be a good starting point for investigation of shape Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 51 evaluation and technical assessment of design proposals. An example of such a matrix is given below. A ctivities associated with the lightweight structures Figure 5-1: Components of a Light Weight Structure (Source: Fooks 1986) The bubbles above demonstrate how various factors are important and what are the activities associated with the teaching light weight structures (figure 5-1). They are in clockwise order - interactive data file systems, model making workshops, 3D measuring machine, basic computer analysis package and specialist consultants. 3D analysis machines as well as analysis packages may not be added in the tool that we have been Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 52 discussing. 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M p c » i« v d a G K > i4 f t s & & & ' % > ' wdbs.’ Figure 5-2: Typical Data Entry Sheet (Source: Fooks1986) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 53 On the one hand the possibility of developing a tool that establishes the necessary ‘vocational background’ and readies a student to use his skills to implement the knowledge in design. To ensure better comprehension we will chart out the different types of design analysis and pick out the most important ones for further examination. s c : - ] . Suspension bridge I I I : Red = compression Blue = tension Figure 5-3: A stayed and suspended bridge (Source: Locke 2002) 5.3 Cable Stayed Structures and Suspended Structures Next, examine the similarities and dissimilarities of Stayed and Suspension systems. The best typologies of examples which may be considered for better understanding are bridges (http://www.brantacan.co.uk). Bridges, especially the ones that have cables as a part of their configuration are easily comprehended by everyone (figure 5-2). The synergy seen in bridges is a Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 54 direct hint at how the system works and functions. The cable-stayed bridge is becoming very popular, being used where previously a suspension bridge might have been chosen. Very large spans have been built, for example - Tartara, Hiroshima, Japan, 2919 feet, Pont de Normandie, France, 2808 feet, Quingzhou Minjang, China, 1984 feet. The main parts of each type of bridge are listed below. Cable Susaended System Cable Staved System Two towers Single or m ultiple masts Hangar Cables Inclined Cables Anchorages are important Anchorages may be eliminated Funicular Shape of a suspended cable Tensile strength of stretched cable Deck is simply suspended Deck is pulled towards the mast Resist torsion and bending Resist thrust and compression Deck cannot be cantilevered Deck can be cantilevered Aerodynamic stability is very important Stiffness governs stability Deck is not stiff Deck is stiff even during construction Figure 5-3: Distinguishing Features (Source: Locke 2002) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 55 5.3.1 Salient Features Both types of bridges have towers and a suspended deck structure. Whether the towers are equivalent may become apparent (based on span and type of loading). There is a difference in the deck structures. The deck of a suspension bridge merely hangs from the suspenders, and has only to resist bending and torsion caused by live loads and aerodynamic forces. The cable-stayed deck is in compression, pulled towards the towers, and has to be stiff at all stages of construction and use. A great advantage of the cable- stayed bridge is that it is made of cantilevers, and can be constructed by building out from the towers. Not so a suspension bridge. Once the towers have been completed, steel cables have to be strung across the entire length of the bridge. These are used to support the spinning mechanism, used since the time of Roebling and the Brooklyn Bridge, which takes thousands of strands of steel wire across the bridge. 5.3.2 Synergy Since the cable-stayed bridge is well-balanced, the terminal piers have little to do for the bridge except hold the ends in place and balance the live loads, which may be upward or downward, depending on the positions of the loads. A suspension bridge has terminal piers too, unless the ends are joined directly to the banks of the river. The cables often pass over these piers and Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 56 then down into the ground, where they are anchored, and so the piers have to redirect the tension. The four anchorages of a suspension bridge have to withstand the tension of the four cable-ends, and are often massive constructions. If the bridge is built on difficult ground, the anchorage can present a problem. The deck of a suspension bridge is usually suspended by vertical hangers, though, some bridges, following the example of the Severn Bridge, use inclined ones to increase stability. But the structure is essentially flexible, and great effort must be made to withstand the effects of traffic and wind. If, for example, there is a daily flow of traffic across a bridge to a large city on one side, the live load can be asymmetrical, with more traffic on one side in the morning, and more traffic on the other side in the evening. This produces a periodic torsion, and the bridge needs to be strong enough to resist the possible effects of fatigue. 5.3.3 Stability and Stiffness Great attention needs to be paid to aerodynamic stability in suspension bridges. The effects of wind are much better understood than they used to Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 57 be, and the advent of the streamlined deck, used first in the Severn Bridge, have reduced the cost of suspension bridges. The box-section of the Severn Bridge contributes not only to aerodynamic stability, but to torsional stiffness. This and the inclined hangers owe much to the ingenuity and imagination of Fritz Leonhardt. The greater inherent rigidity of the triangulated cable-stayed bridges, compared with the suspension type, makes the task easier for their designers and builders. On the other hand, if a cable-stayed bridge is built by the cantilever method, it is vulnerable when the structure is very long but has not yet been joined together. Although the popularity of the cable-stayed bridge is a fairly recent phenomenon, the principle is not new. The great Brooklyn Bridge combines cable-stays with conventional suspension cables, while other bridges have used stays, even below the deck, to resist aerodynamic forces. The Albert Bridge, a small suspension bridge across the river Thames in London, also employs some stay-bars as well as a suspension chain. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 58 5.3.4 Suspension Structures In suspension structures, apart from the towers, which are in principle simple struts, all the most highly stressed parts of the structure are in tension. A cable, though flexible, is inherently stable against perturbations, and need only be thick enough to withstand the tension, with a safety factor. A strut is inherently unstable, and needs to be thick enough to prevent buckling. The forces of a suspension system are carried to the tops of high towers, which have to be resistant to buckling, flexure, and oscillation. 5.4 Components of a System To understand how suspended and stayed systems work, it is important to understand what the different components are, and how they work. These principal elements (Howard, 1966) are very important and are always present in a system in one form or another (figure 5-6). I. Vertical Supports or towers: The vertical elements provide the necessary vertical reaction which keeps the cable system above the ground. Mostly all systems require such towers and may be in the form of sloping piers, masts, diagonal struts, or a wall. Ideally, the axes of the supports should bisect the angle between the cables which pass over them. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 59 IS . Main Cables: These form the tensile elements, carrying the roof (or sometimes the floors) with a minimum of material. The drawing of steel with proper carbon content into fine wires increases the proportionai limit up to stresses on the order of 160,000 psi and the breaking stress to over 220,000 psi. Figure 5-5: An Anchorage (Source: Locke 2002) ilk Anchorages: Although the main cables carry their loads in pure tension, they are not usually vertical, while the gravity forces are. Hence anchorages are used to provide the horizontal force. In suspension Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 60 systems the cables are carried over the towers and into massive concrete abutments with each wire locked into an anchorage (figure 5-5). IV. Stabilizers: The fourth element i.e., stabilizers are used to keep the cables in shape. Stabilizers ensure that the cables do not change their curves when the load changes or undulate and flutter when acted upon by wind currents. In extremely large spans (2,500 feet or above in bridges) the moving loads of vehicles may be insignificant compared to the weight of the cables, suspenders and floor decks. In case of some suspension systems, a relatively rigid truss or girder spreads moving loads and hence maintains a condition of uniform load on the main cable. Suspensions bridges have also been built with the suspenders set diagonally for bracing or with a separate set of diagonal stays. The floor deck system must also be designed to resist torsion caused by wind. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 61 Figure 5-6: Typical Components of a Suspension Bridge (Source: Locke 2002) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 62 Chapter 6. STRANDS and WIRE ROPES 6.1 Strand A strand is an arrangement of wires helically laid around a center wire, to produce a symmetrical section (figure 6-1). In the steel cable industry, strand has two basic uses. First, strands are used in the manufacture of wire rope as a component part of the final product. Typical strands for this application include 7, 19, 37 and 61 wires. 7 -W ire Strand Figure 6-1: Strand cross section (Source: Gensert 1966) Strand is also used as an individual load carrying tension member where flexibility or bending is not a major requirement but the greater stiffness of strands is desired. For any given overall diameter, strands will always be the less flexible of steel cables. A strand, of appropriate size for a specified load, provides the maximum strength-to-weight ratio for a given diameter of cable. It is this feature that permits successful adaptation of strand to structural Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 63 applications. Individual strands are manufactured in diameters through 4 inches, and can contain as many as 300 wires. 6.2 Wire Rope A wire rope is a plurality of strands laid helically around a core. The core may be a fiber rope, another steel strand or a small wire rope (figure 6-2). Wire ropes provide more flexibility than individual strands and generally contain 6 or 8 strands plus the center core. For structural applications, wire rope consisting of 6 strands laid helically around a center strand is commonly used. Wire rope is manufactured in nominal diameters through 4-1/4 inches. 6-Strand its lip Figure 6-2: Six strand Wire-rope cross section (Source: Gensert 1966) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 64 6.3 Prestretching Wire Rope and Strand As compared with most steel products, wire rope is a relatively elastic product, and for most service requirements the normal as-manufactured condition provides safe and satisfactory service life. For certain requirements, however, such as for main cables and suspenders of suspension bridges, guy ropes for high towers, cable supported roof structures and similar applications, the wire rope should approach closely a condition of true elasticity. To secure this condition, stretching of the as- manufactured rope or strand is necessary. 6.4 Reasons for Prestretching Prestretching may be defined as the application of a predetermined tension to a finished wire rope or strand for the following reasons: 1. To make the rope or strand truly elastic by removing the “ constructional looseness” inherent in the product as it comes from the stranding or closing machines. This is essential for most suspended or guyed structures, since it enables the designer to predict better the elastic behavior of the rope or strand after erection of the structure. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 65 2. To permit measuring and marking, under prescribed loads, of the proper spacing on the rope or strand of such locations as the centers of towers and suspenders. The elongation of a wire rope or strand under tension is due to: (i) The elastic or recoverable stretch of the steel itself (ii) The non-elastic constructional or permanent stretch, which is a variable quantity depending upon the dimensions of the stranding. The elastic strain of the steel permits a full recovery to the original condition and length, upon release of an applied tension, provided the tension does not exceed the elastic limit of the steel wires. Constructional stretch, on the other hand results in a permanent set or increase in length when tension is applied and then released. 6.5 Removal of Prestretch The amount of constructional stretch in rope or strand can be minimized by the use of proper sizes of wire and lengths of lay, and by fabrication on heavy, rugged machinery, but it cannot be entirely eliminated. If the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 66 constructional stretch must be reduced to minimum amounts, the rope or strand must be subjected to tension after fabrication. With constructional stretch eliminated, any given working tension, or load of predetermined relation thereto, can be applied and overall lengths and fitting positions can be measured and located within closed tolerances. 6.6 Strands vs. Ropes Ropes are more flexible than strands. This means that ropes are easier to handle and where cables have to pass over saddles, smaller radii can be used for a rope than for a strand. Owing to their greater bending stiffness, strands develop bending stresses, particularly at clamps and terminal fittings. Strands have a greater modulus of elasticity and so cable roofs made from strands deflect less. However, this also means that extensions are smaller and therefore, greater accuracy is required on length tolerances. Strands have a better strength/weight ratio. Ropes are easier to grip than strands. 6.7 Technical Details • For Strands, Metallic Cross Section Area (Am) is 70 percent of Gross Area (Ag) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 67 • For Wire-ropes, Metallic Cross Section Area (Am) is 60 percent of Gross Area (Ag) • Strands have higher E-modulus, ranging from 22,000 to 24,000 ksi • Wire-ropes have lower E-modulus, ranging from 12,000 to 18,000 ksi ® Allow Cable stress Fa = 70ksi (it is 1/3r d of Breaking Stress, Fy = 210ksi, where 3 is a factor of safety) • The E modulus is approximately 1000 times the breaking stress. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 68 Chapter 7. Concepts of Suspended Structures 7.1 The Components For any practical suspension system, the following elements are of crucial importance (Howard, 1966). I. Vertical supports: These provide the essential reactions to keep the cable system above the ground. Vertical supports may be sloping piers or masts, diagonal struts or a wall. Ideally, the axes of the supports should bisect the angle between the cables which it supports. II. Main Cables: These are the tensile elements carrying the roof (or floor) with a minimum of material. It is important during the manufacturing process to draw the steel with the right amount of carbon content into fine wires. Additionally this increases the proportional limit up to stresses in the order of 160,000 psi and the breaking strength of 210,000 psi. III. Anchorages: An anchorage must resist vertical and horizontal reactions. To resist those reactions effectively requires careful integration with the sub structure. For example circular compression rings or grand stands may be effective to resist horizontal thrust. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 69 IV. Stabilizers: Stabilizers are required to keep the cables in shapes, to prevent them from changing their curves when the load changes and to prevent them from undulating or fluttering when acted upon by wind currents. In some cases gravity dead load acts as the best stabilizer. However in seismic areas the additional dead load causes increased seismic forces. In suspension bridges, that exceed span limits of 2500 feet, the forces of winds and vehicular traffic may be insignificant compared to the weight of the floor deck. Usually in case of bridges rigid truss assists spreads the moving loads among the suspender cables and maintain a condition of uniform load on the main cable. In some cases the suspenders act as a set diagonally for bracing. The floor deck system must also be designed to resist torsion caused by wind. Support Towers Hangars Anchorage Cable Cable Parabolic u f = io CL/10) Deck Anchorage Sag.? CABLE SUSPENDED BRIDGE Figure 7-1: A cable suspended bridge (Source: Schierle 2003) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 70 7.2 Problems in Buildings Among the many questions that arise during the design of the roof surface, one of the main queries is as to what should be used to span between the cables, if the materials used are wood planking, metal decking or concrete slabs, then these are rigid and can resist normal (perpendicular) forces by bending stresses. The problem of flutter and movement is eliminated for the surface but remains for main cables. 7.3 Stabilizing Factors These may be the dead weight, a rigid surface that includes the main cables, a set of secondary pretensioned cables curving upwards combined with the tie-down cables acting normal to the surface, or a second set of cables pretensioned together with the main cables to form a rigid system. 7.4 Lability or the Tendency to Move This is one of the most complicated problems in designing a suspension structure. The most familiar issues associated with the design are the behavior of cables, towers and anchorages under static loads. The less familiar issues are the behavior and effect of unbalanced loads and of changing geometry caused by such load on the system. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 71 7.4.1 Non-destructive Movements Changes in Shape due to asymmetrical loading: Such instances may be due to snow, over only a portion of the roof. The greater the live load / dead load ratio, the greater the movement. Pretensioning can be used with the same general effect as an increase in the dead load as described under Stabilizing Factors. Changes in shape due to wind loads: On a single cable, a steady wind will act normal to the roof surface. On a roof surface, it will act principally as an upward force (suction), unless the slope is over about 30°. The means of resisting such a load is by providing secondary tie down guy wires or of dead weight. Temperature Changes must be considered: All cable sockets act like hinges change due to thermal expansion during summer and contraction in winters (in suspension cables only the sag will change with thermal extension - in prestressed system the level of prestress will change). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 72 7.4.2 Potentially Destructive Movements Some of these are vibrations, flapping, rippling, fluttering and galloping. Every mass has its own natural period of vibration with its fundamental or higher modes. The period depends on the density of the mass, geometrical distribution or shape, magnitude of stresses, set up by its own weight and the other permanent forces acting on it. For instance, a stretched wire and the musical notes produced, depend on the material, length, and tension. The number of half waves formed by a vibrating wire is always a whole number; hence controlling the vibration can be achieved by irregular spacing of framing members, ties and supports. When an external pulsating force is applied to a mass such as a cable, it will be set into motion. This motion can be represented by an infinite number of superimposed modes of vibration. If one of these modes coincides with the natural frequency or fundamental mode of the mass, resonance will occur. The amplitude or deflection will be increased and result in failure. 7.4.3 Types of Exciting Forces One of the principal causes of vibrations is wind, a principal danger to suspended structures. Additionally vibrations can be caused by the movement of vehicles, operation of reciprocating and rotating machinery on the structure or ground nearby. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 73 a. Wind: Winds generate rhythmic forces which can be detrimental to suspension systems. Karman Vortices are an effect manifested when steady wind blows against a surface, for instance a cylinder or any obstruction, the wake becomes a stream of vortices. Shedding of these vortices on the leeward side causes forces to act on the object at right angles to the direction of the wind, first from one side and then from the other. To counter such forces, springs and small shock absorber type dampers have been developed to prevent these failures. For instance, a Karman Vortex about 39 feet long was a contributing cause of the Tacoma Narrows Bridge collapse. b. Dynamically Unstable Shapes: The force of wind on a prismatic shape is usually not in line with the direction of the wind. The analyzing effect of a force can be deduced into two force components, the drag and the lift which act parallel and perpendicular to the wind direction. The magnitude of forces will vary with the changes on the angle of attack and with the section. 7.5 Damping A structure or a part of a structure which has been set into vibration by a single force will not continue to vibrate forever. Air resistance and internal friction causes it to stop. But it is necessary to minimize vibration or to dampen it as quickly as possible, if a damping force can be provided which Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 74 acts in the opposite direction to that in which the structure is moving when vibration starts and if that force is proportional to the velocity of the structure (the faster it moves, the greater the damping force), vibration can be prevented or greatly diminished. Often called viscous damping, (a small plunger in a dashpot filled with a viscous liquid will provide this type of resisting force) it is similar to the action of the cylinder of a door closer. 7.6 Design Considerations Some of the important notations and values for design considerations: i. Strand (good stiffness, low flexibility) £ = 22,000 ksi to 24,000 ksi ii. Wire rope (good flexibility, low stiffness) E = 12,000 ksi to 20,000 ksi Figure 7-2: Strand cross section Figure 7-3: Wire-rope cross section (Source: Gensert 1966) (Source: Gensert 1966) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. iii. V = Vertical Reaction iv. H = Horizontal Reaction V. T = Tension of cable at highest support vi. LL = Live load vii. DL = Dead Load viii. w = uniform load per liner foot ix. f = sag X. L = Span of system between supports xi. M = Global moment xii. A g = Gross Cross Section Area of cable or strand xiii. Am = Metallic Cross Section Area of cable or strand xiv. Fa = Allowable Stress XV. E = Modulus of Elasticity Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 76 Chapter 8. Concepts of Stayed Structures 8.1 The Basics The cable-stayed deck is in compression; pulled towards the towers, and has to be stiff at all stages of construction and use (figure 8-1). A great advantage of the cable-stayed bridge is that it is essentially made of cantilevers, and can be constructed by building out from the towers (Locke 2002). Since the cable-stayed structure is well-balanced, the terminal piers (if present as in bridges) have little to do for the structure except hold the ends in place and balance the live loads, which may be upward or downward, depending on the positions of the loads. Roof / Floor Deck Figure 8-1: Deck and Stay cables Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 77 The greater inherent rigidity of the triangulated cable-stayed bridges, compared with the suspension type, is a great advantage. On the other hand, if a cable-stayed bridge is built by the cantilever method, it is very vulnerable when the structure is very long but has not yet been joined together. The penalty for the sloping cables is the compression induced in the deck (figure 8-2). Tension Cafcle Stayed.. . System Figure 8-2: A single bay of a Stayed System Very long cables oscillating in their fundamental mode can store a great deal of energy, so the larger structures, especially bridges, are equipped with light Bedrock / Foundation Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 78 cables that run across the planes of main cables and connect them all together, and eventually to the deck. 8.2 Learning from Bridges as examples Cable stayed bridges are apt to look somewhat angular and highly stressed (Locke 2002). The design makes no attempt at disguising anything: all the parts are so clearly visible that the bridge could be used as a textbook example. The tower is essentially an A-frame or shear legs, but instead of continuing to an apex, it is truncated, rigidity being provided by the tension ring, which also supports the two vertical cable supports. These supports continue above the cable attachments, tapering to provide a neat finish to the tower. Figure 8-3: View of different Towers from the deck in cross section (Source: Locke 2002) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 79 In the figure 8-3, the view from the road shows a somewhat disordered appearance of the cables. This can be even worse if the cables are fanned out from a horizontal row of holes in the pylon. To achieve a vertical plane of cables, the second arrangement can be used, but now the tower is not elegant. Another solution is to abandon the idea of a vertical plane and make an A-frame, as in the right hand pair of diagrams. An A-frame is very rigid. A third way is to use only a single plane of cables, relying on the deck to provide stiffness against torsion. 8.3 Radial and Harp Systems The cables can be parallel or fanned from a point, or arranged in an intermediate pattern. They can be reduced to only two in number, or even one, per side. In some types, instead of two planes of cables, a bridge can be furnished with a single set along the center line. There are even examples where the plane of the wires is far from vertical. If the cables fan from a point, as seen from the side, they must originate from a horizontal line. However short this is, it will effect the appearance from certain angles, because the cables are not coplanar. In fact, in most cable-stayed bridges, the multiplicity of sloping cables is liable to lead to a disordered appearance unless care is taken. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 80 Although the cable-stayed bridge is inherently stiffer than a suspension bridge, the relationship is reversed during construction. Construction of the deck of a suspension bridge does not begin until the cables are complete, and so all parts of the bridge are connected, however tenuously. But the cable-stayed span is built out in stages from each tower, and when the span is almost complete, the long cantilevers are at the mercy of the wind. If a system of fanned cables is used, the system is called a ‘harp’ system (figure 8-4). In such a system, the inner cables share equal forces except the outer one which carries the most tension. Harp System Figure 8-4: A typical bay of the Harp system Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. If the system of cables is fanned from a single point on the mast/tower, the system is called a ‘radial system’ (figure 8-5). In this system the compression of the deck along the span varies as does the force in each cable. Radial System Figure 8-5: A typical bay of the Radial system Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 82 Chapter 9. ASCE Design Guidelines for Cable Systems 9.1 Design Loadings Load provisions should be based on the considerations of aerodynamic effects on individual cables and complete cable structures, either through numerical dynamic analysis or through wind tunnel tests; wind induced structural vibration and fatigue effects; and earthquake effects (ASCE 1997). In the absence of an applicable local building code, the design loads shall be those given in ASCE 7, Minimum Design Loads for Buildings and Other structures. 9.2 Load Combinations Cable tensions shall be calculated for the following load combinations: • Ti = Cable tension due to DL (dead load) + F (prestress force) • T2 = Cable tension due to DL + F + LL (live load) + (roof live load or snow load or initial rain water load) • T3 = Cable tension due to DL+ F + W (wind load) or E (earthquake load) • T4 = Cable tension due to DL + F + LL + (roof live load or snow load or rain water load) + W or E Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 83 9.3 C able Strength The design strength of each cable shall be equal to or greater than: 2 (Ti), 2 (T2), 2 (T3), 2 (T4). This criterion shall be satisfied for the full range of temperatures to which the structure will be subjected. 9.4 Fitting Reduction Factor The factor to be applied due to the action of the end fitting in transferring tension from the cable to the fitting is given in the table below. This factor may be determined in the final stages of design. 9.5 Elevated Temperature Effect The effect of elevated temperature on the physical properties of cable and end fittings shall be considered during the design. 9.6 Fatigue Effect The reduction in cable strength due to fatigue effects shall be considered. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 84 9.7 End fittings Fittings shall develop an ultimate strength of at least 110 percent of the specified nominal cable strength. 9.8 General Considerations for Structural Analysis • Elastic stretch of the cables and deformation of the supporting structure shall be taken into account in the design. • Non linear analyses shall be performed if it is determined that the magnitudes of the cable displacements are such that the equilibrium equations should be based on the geometry of the displaced structure. 9.9 Vibrations The effect of dynamic loading on cable stresses, fatigue and deflections of the individual cable and the entire structure shall be considered in the design. 9.10 Deflections Cables supporting floors and roofs shall be so proportioned that the maximum deflection under the combined action of applied loads and cable stretch will not damage the supported or adjacent structure. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 85 9.11 Cable Materials 4.1 Cable Specifications This Standard applies to cables conforming to the follow ing standard specifications: ASTM A416-90A, Steel Strand, Uncoated Seven-Wire Stress-Relieved Steel Strand fo r Pre stressed Concrete. ASTM A 4 7 4 - 8 6 , Aluminum-Coated Steel Wire Strand. ASTM A 4 7 5 - 8 9 , Zinc-Coated Steel Wire Stmnd, ASTM A492-92, Stainless and Hem Resisting Steel Wire Rope, ASTM A586, Zinc-Coated Parallel m d H elical Steel Wire Structural Stmnd, ASTM A603-8S, Zinc-Coated Steel Structural Wire Rope. ASTM A779-9§» Stm l Strand* Seven-Wire, Uncoated, Compacted, Stress-Relieved fo r Prestressed Concrete. ASTM A855/855M-89, Z iw —5% Aluminum- Mischmetal A Hoy-Coated Steel Wire Strand. ASTM AS82/8S2M-91 s Epoxy-Coated Seven- Wire Prestressing Steel Strand, Some of the above cable specifications apply to cables of a specific construction. This Standard does not exclude cables of other construction provided that the chemical and mechanical properties of the wires constituting the cables conform to the require ments of one of the above specifications. Figure 9-1: Cable Materials Specifications (Source: Howard 1966) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 86 9.12 Erection Analysis A structural analysis shall be performed for the suggested or mandatory erection procedure to check for vibrations, deflection, etc. 9.13 Prestretching For each type and construction of cables specified in the contract documents, the prestretching requirements shall be explicitly stated. For prestretched cables, the minimum value of the modulus of elasticity of the cable after prestretching shall be specified. Prestretch force should not be less than 50 percent of the nominal cable strength of cables that are 2-1/2 in (63 mm) in diameter or less, except if it can be physically demonstrated by the manufacturer that the specified minimum modulus of elasticity can be attained at a lower prestretch force. For cables over 2-1/2 in. in diameter, approved prestretching requirements shall be developed in consultation with the cable manufacturer. 9.14 Miscellaneous Considerations • Selection of fitting materials should be based on compatibility of the material with that of the cables Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 87 • Standard sockets should be control tested and special fittings should be subject to additional inspection • Positioning of end fittings should be such that dirt and moisture should not accumulate • Surface of the saddle in contact with rope or strand shall be free of projections and all sharp edges and corners • Exposed cables should have corrosion protection equivalent to Class A Zinc coating as defined in ASTM A586 and A603 and fire protection as well • Prestretching will confer to ASTM specifications to achieve required E modulus • Length measurements of the cable shall be made under the cable tensions specified in the contract documents • Erection procedures should be followed as per contract documents and these shall reflect all assumptions regarding the sequence • Intermediate clamps and fittings shall be attached in a manner that will not damage the cables ® Approved recommendations shall be followed while installing permanent fittings in a manner that will not damage the cables Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 88 Chapter 10. Stayed Systems vs. Suspended Systems 10.1 introduction The discussions untii this stage have broadly covered many common factors that are elemental to both stayed and suspended systems. But a clear differentiation between the two systems needs to be identified thereby establishing the uniqueness of each style of construction. The ideal means of distinguishing between these systems is by determining, how each system works, what are the components and the typology under each category. 10.2 Definitions Before defining both systems we have to understand both systems have towers and decks. The cables are carried over the towers with the help of saddles and then anchored into anchorages or bedrock as in case of bridges. The cable suspension system was the first to be developed and used for bridge construction. Whether the towers are equivalent may become apparent. The stayed system seems better since multiple anchorages may not be necessary depending on the type and number of masts used. Stayed systems are later developments which utilize the tensile capacity of high strength steel cables. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 89 Cable Suspended System: In this system the sag of a freely suspended cable is utilized to support roofing or flooring systems (Locke 2002). The tensile capability of the ‘funicular’ shape is used and this supports the deck which merely hangs from the same with the help of hangars, hence the resistance to bending and torsion is essential (figure 10-1). The deck is subject to aerodynamic forces and can warp; hence stabilizing is of primary concern. Support Towers / Hangars Anchorage Cable Cable / Parabolic u f = io / (L/10) Deck Anchorage CABLE SUSPENDED BRIDGE Figure 10-1: A cable suspended bridge (Source: Schierle 2003) Cable Stayed System: In this system the tensile capability of prestretched high strengths cables is used to support a horizontal deck that is stiff (Locke Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 90 2002). This is since, the deck is pulled towards the towers and hence compression and bending becomes inherent in the deck (figure 10-2). It is important to note that the deck can be cantilevered from the tower and the outer most cable hence receives maximum amount of tension. Inclined Mast Figure 10-2: A cable stayed system (Source: Schierle 2003) Anchorage Cables PROFILE OF A FREELY SUSPENDED CABLE Figure 10-3: Freely Suspended Cable (Source: Schierle 2003) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 10.3 Differentiation The following table describes the similarities and dissimilarities between the two systems (Locke 2002). Cable Staved Svstem Two towers Single or m ultiple masts Hangar Cables Inclined Cables Anchorages are important Anchorages may be eliminated Funicular Shape of a suspended cable Tensile strength of stretched cable Deck is simply suspended Deck is pulled towards the mast Resist torsion and bending Resist thrust and compression Deck cannot be cantilevered Deck can be cantilevered Aerodynamic stability is very important Stiffness governs stability Deck is not stiff Deck is stiff even during construction Figure 10-4: Distinguishing Features (Source: Locke 2002) Some other features are listed below: • A great advantage of the cable-stayed system is that it is essentially made of cantilevers, and can be constructed by building out from the towers. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 92 Suspension bridge , m ! m t s — JLsmS™ R e d ® compression Blue = tension / ./... Figure 10-5: A suspension and stayed bridge (Source: Locke 2002) • In case of suspension system, once the towers have been completed, steel cables have to be strung across the entire length of the deck to assist the spinning mechanism as is done in bridge construction • The vertical hangars of a suspension bridge can be inclined to increase stability. • In a stayed systems the cables can be directly anchored to the main mast and the mast can be inclined to offer additional stability • Because the cable-stayed system is well-balanced, the masts have little to do except hold the ends in place and balance the live loads, which may be upward or downward, depending on the positions of the loads. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 93 inclined Cables Anchorag Tension Inclined Mast Figure 10-6: A Stayed System (Harp) (Source: Schierle 2003) Anchorage Cables Support Towers CHANGING PROFILE OF A FREELY SUSPENDED CABLE FOR DIFFERENT LOADS Figure 10-7: Changing Profile of a freely suspended cable for different load locations (Source: Schierle 2003) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 10.4 Different Profiles of Funiculars ! 2 I 4 3 6 5 7 6 Figure 10-8: Profiles of funiculars (Source: Schierle 2003) Figures 1 and 2 Circular (radial load) Figures 3 and 4 Catenary (cable / arch DL) Figures 5 and 6 Parabolic (horizontal [uniform code] load) Figures 7 and 8 Cubic parabola (triangular load) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 95 10.5 Suspension Roofs Lean Back to Resist Lateral Thrust m Figure 10-9: Piers at Dulles Airport, Chantilly (Source: Schierle 2003) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 10.6 Force vs. sag/span ratio Large sag = small forces Small sag = large forces L/f =10 = optimum R = vertical reaction (constant) H = horizontal reaction T = Maximum cable force I4TH tW r r flf Figure 10-10: Force vectors based on funicular profiles (Source: Schierle 2003) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 97 Chapter 11. Graphic Vector Analysis Method 11.1 Introduction to Vectors The simplest, and accurate way of finding how forces work, the analysis involved and visualizing the same is achieved through the Graphic Vector Analysis method (Schierle 2003). It was first used by Leonardo Da Vinci and since then this method has been accepted as a simple alternative to detailed numeric analysis for better comprehension. In case of this method, the use is restricted to the analysis of statically determinate systems only. While only two-dimensional forces are described, vectors may represent forces in a three dimensional space as well. Figure 11 -1: A simple vector (Source: Schierle 2003) Magnitude: vector length at a scale, like T’ = 1k Line of Action: slope and location in space Direction: arrow pointing in direction of force Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 98 To better understand how this analysis works, let us look at the concept of vectors. Vectors are defined by magnitude, line of action and direction. They are represented as a straight line with an arrow head that defines direction (figure 11-1). The magnitude is defined as the length of the vector, the line of action is the slope and location in space while the direction is the arrowhead pointing in direction of the force. 11.2 Examples of Analysis The study of vectors is best understood from examples represented graphically to gain a better understanding of the analysis. Consider two forces, P1 and P2 pulling in two directions, with different magnitudes (figure 11-2). The resultant of these two forces is R, with the same result as P1+P2 combined, is found in a force parallelogram, as in case A or as in case B which represents a force triangle. Lines in the vector triangle are parallel to corresponding lines in vector plan, as in case A. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 99 P2 1 ResuHani, B Figure 11-2: Finding an Equilibrant for two vectors (Source: Schierle 2003) For any system to be in equilibrium, all acting forces have to be balanced (Schierle 2003). Hence an equilibrant has to act which has the same magnitude as the resultant, but is opposite in direction as the resultant. The figure below is how an equilibrant works. The forces are the same, but now instead of the resultant R, the equilibrant E is active (figure 11-3). Always, note that the resultant, equilibrant doses the force triangle head to tail for the system to be represented as at rest. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 100 P1 P 2 C Figure 11-3: Finding an Equilibrant for two vectors (Source: Schierle 2003) If three forces are considered, as shown in the figures below, the equilibrant of the three forces is found by combining resultant R1-2 with P3 (figure 11-4). This process can be repeated for a multiple number of forces, and the interim resultant is desirable for better visualization, although it is not mandatory to represent the same. The equilibrant is located at the intersection of all forces as in case D. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 101 Finding the equilibrant may be stated as follows: “The equilibrant closes a force polygon with ail vectors connected head-to- tail; and puts them in equilibrium in the force plan” (Schierle 2003). P3 P2 Equilibrant, E R esultant;. R f - 2 Figure 11-4: Finding the Resultant and Equilibrant for three vectors (Source: Schierle 2003) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 102 The same analysis above can be represented as shown below in the next set of figures. Only in this case the interim resultant R1-2 has been eliminated for easier comprehension. Equilibrant, P1 D p i P3 Figure 11-5: Finding an Equilibrant for three vectors (Source: Schierle 2003) The equilibrant of forces without cross point as in case G is found using the following steps, viz. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 103 i. First resultant R1-2 is found as in case H, and located at the intersection of P1 and P2. ii. P3 is then combined with R1-2 to find the equilibrant for all three forces, located at intersection R1-2 with P3 in the force plan (figure 11-6). The process may be used for any number of forces. P2 P 1 P3 P2 P3 \ Resultant \m-2 Equilibrant E Figure 11-6: Finding an Equilibrant for three vectors (Source: Schierle 2003) 11.3 Component Vectors Component vectors have the same effect on a body as the vector for which they are components of. The components relate to a vector as two vectors Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 104 relate to an equilibrant. For instance, in the example below, the component forces C1 and C2 in two rods supporting load P are found by a force triangle as demonstrated in case B, with corresponding lines parallel to those in vector plan A as in case A (figure 11-7). p C2 B C2 Figure 11-7: Component Vectors (Source: Schierle 2003) In some instances, as demonstrated below, the forces in more than two rods supporting a load P are found to be statically indeterminate since they have infinite solutions as demonstrated in case C (figure 11-8). The solution requires additional components like stiffness, cross section of members, length and modulus of Elasticity, E. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 105 02 P C3 C3 € D Figure 11 -8: Statically Indeterminate Component Vectors (Source: Schierle 2003) It is important to note that only two components can be found by Vector Analysis Method. A simple case is demonstrated above for understanding how magnitudes are treated. The magnitude of each force is indicated in case E, with the vectors drawn to a force scale (figure 11-9). A force polygon as show in case F is then constructed. For accuracy the force scale should be as large as space permits. The line of action of the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 106 equilibrant (or resultant) is transposed to the force plan at the intersection of all force vectors as shown in case E. Thus, the magnitude of the equilibrant can be determined. Pi =3 P3 = 2 E P2= 1 E = 4.5 F Figure 11-9: Force Polygon for three vectors (Source: Schierle 2003) 11.4 Numeric Vector Analysis Method (Alternative Method) The Optimal span/depth ratio = 1:10 for architectural applications, hence the sag can be computed as L/10. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 107 One of the simple ways of computing reactions is by the Vector Analysis Method, where in forces are treated as vectors that are defined by magnitude and direction. One way to explain the working of a vector diagram is that the vectors are a representation of the flow of forces through a structure. This makes it easier to visualize how the forces act and hence reactions can be computed. The vectors hold good for representing quantities such as velocity, displacement or forces. The magnitude is the vector length scaled to a quantity, for instance 1” = 10K or 1cm = 50kN. A force parallelogram can then be plotted with which the reaction is computed. The equilibrant is equal in magnitude but opposite in direction to the resultant. For a case with three forces, the equilibrant of the three forces is found combining the interim resultant R1-2 of forces P1 and P2. Similarly the sag can be determined by tracing the cable profile achieved by dividing the two lines of force into equal segments. These lines connecting form the parabolic cable envelope. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 108 C h a p te r 12. Case S tu d y : Renault Parts D istrib u tio n C en ter, Swindon, UK 12.1 Design Approach The building form reflects Sir Norman Foster’s basic principles of industrial building design where in the architectural form should have the potential for random growth over time (Harris & Li, 1996). The second principle was that the depth and scale of the space within which the workers are employed must enable them to have a view of the outside. The form of the Renault Center meets this criterion by being based on modular units extendible in any direction to fill out the irregularities in the site. 12.2 Functional Requirements Renault UK required 20,000m2 (215,278.2sq.feet) of warehouse space with a training school, restaurant, office, and showroom space amounting to about 25,000m2 (269,097.8sq.feet) in total. Since spare parts for cars come in wide range of sizes, fully automated storage systems were not suitable. Additionally, an AGV system would be employed to automate the warehouse functions apart from being manually operable. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 109 For this kind of installation a spatial module about 24m square (260sq.feet) and 8 m high was found to be optimum. It was to achieve the structural depth for this span and keep its encroachment on the internal space to a minimum that the undulating suspension structure was developed. In fact, the internal height varies from 7.5 m to 9.5m. Figure 12-1: Axonometric View of Renault Parts Distribution Center (Source: Harris & Li 1996) 12.3 Structural Concept and Analysis The initial proposal was for a series of independent structural umbrellas, developed from a single mast with radiating cable stated beams. However, a relatively large, two directional structure of this kind would have required Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 110 some form of internal bracing and expansion joints, which were deemed unacceptable. Consequently, the initial concept of a series of square modules with central masts and radiating beam umbrella structures was replaced by one based on masts at the corners of the modules, with arched cable-stayed beams spanning orthogonally and diagonally between them (figurel 2-1). This design was then developed as an unbraced, two directional portal frame. In this form, loading on one bay affects the behavior of adjacent bays and the beam elements play a role in spanning not only between the pre stressed ties but also between the masts themselves. There are no special expansion joints as all movement is taken up within the structure itself. Most importantly, the required structural depth is provided outside the building envelope which can thus have a correspondingly lower profile. For reasons mainly of appearance, the structure comprises of continuous bending masts pinned by continuous bending beams, linked and stiffened by members capable of supporting only tension. This concept means that it is the variations in the conditions of loading which determine the elements Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 111 which are under stress. The tension members are stressed by the uniform downward loads. Analyses were carried out for each of the critical arrangements of loads. The most severe loading was associated with a 1:50 year wind, a dominant opening on the windward face and an asymmetric distribution of live load. The factor of safety against destress in the tension members was chosen to be in excess of 1.5. Additional checks were carried out on three of the dynamic features of cable stayed structures: i. Eddy shedding in cross-winds producing vibration in the ties ii. Down-wind ‘galloping’ in the ties iii. Roof ‘snatch’ movement under wind uplift producing over-stress in the ties 12.4 Structural Form The completed first stage comprises forty-two spatial/structural cells with each cell being 24m square, defined by four 16m high CHS masts. Between the masts, two systems of arched beams, at right angles and diagonal, form the main structure (figure 12-2). These beams are trussed at their centers by rods and struts and are supported at their quarter points by steel ties connected to the top of the building services, steel purlins are located at 4m centers, spanning between both beam systems and forming a central square roof-light in each module. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 112 The arched steel beams were tapered by cutting the web at an angle, reversing the section, and re-welding. Shear forces are not large in such situations and the welding was not required to be continuous. The tie members are Grade 50C steel where there may possibly be destressed, and Macalloy rods form the four pre-stressed ties next to the masts. Stressing this system was carried out using the Pilgrim Nut hydraulic jacking system developed originally for stressing nuts in ships’ boilers. ' ' 1 . . . . . • • 5 - v- mtfc. I Ik. x < ? : > J & '- 0 ' ' x ! y 0 & M Figure 12-2: Axonometric View of a typical Cell Unit (Source: Harris & Li 1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 113 12.5 Connections Mechanical connections are used to couple the ties to the masts. To ensure their durability, particularly in the case of those which are exposed on the outside of the building, it was decided that they should be cast either in iron or steel to give a smooth, well-sealed profile. The chosen material, spheroidal graphitic cast iron, grade 370/317, acts in a similar way to Grade 43 steel, but having been designed to cast unlike steel, the costs of casting, heat treating and machining are about half those of the latter. Quality assurance of the castings was made by testing manufactured prototypes. It was possible to assess: i) The likely defect size ii) The degree of nodularity and ferricity iii) The crack opening displacement (COD) of the material iv) The mechanical properties (yield stress, elongation and charpy values). v) The ladle analysis vi) The velocity of sound which is a measure of nodularity Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 114 Internal stiffening of the masts at the areas of connection of the ties proved to be impracticable at the time. Consequently, the necessary stiffness was achieved by ‘buttering’ the surface of the mast with weld metal before the fitting of annular rings to which the vertical connection places were welded. The roof decking of 100mm deep corrugated steel units is connected to the purlins so as to restrain their compression flanges against lateral buckling. On top of the decking is laid 75mm of rockwool insulation, held in place by 75mm flat metal disc corner fixings. These are pulled down to the decking by self-tapping screws at centers which vary according to the calculated wind uplift at different points on the roof. This high density mineral wool sheet provides exceptional insulation, and works structurally to provide a dead load against wind uplift. Figure 12-3: Cross Section looking through the center (Source: Harris & Li 1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 115 12.6 Construction Structural operations began on site with the assembly of the prestressed elements, namely the masts with their four stub beams and eight prestressed ties. These were stressed using Pilgrim nuts, adjusted to achieve the correct loadings and checked for position to a tolerance of +/- 3mm. They were then erected on the bases with eight holding sown bolts in a circle. The upper parts of the masts were painted before erection for safety reasons and to achieve shop controlled quality. The spanning beams along the main and diagonal grids were assembled on the ground with their lower tension members in place. These complete arched units were then adjusted to the exact dimensions required on site by tensioning the tie rod, lifted into place, and pinned in position. v Ih jcturai analyst was carried ^ out on the basis of the computer shown, loadcases which produced com pression m som e (4 the ties were re-analyswd with the* members omitted Thtsmtanuhst for different c m ibmmm at M fix- principle of superposition could n o t be applied The structure w a r s thus analysed m actual toads aprfitd mi the members included accordingly . Figure 12-4: Computer Analysis of the structure (Source: Harris & L i 1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 116 The upper ties, running from the mastheads to the quarter span points, and attached to a stiffening member of the exact straight line length, were then positioned and fixed with finger tight nuts. The stiffening member was then removed. Because of the angle, weight and induced tension in the ties, their profile is sufficiently straight as to make their load extension characteristics virtually elastic. When the steelwork in one bay was complete, the ties around the masts were again checked with the Pilgrim nuts as the masts were plumbed. Figure 12-5: Image of a typical cell unit (Source: Janberg 2000) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 117 Chapter 13. Case Study: National Athletics Stadium, Canberra, Australia 13.1 Introduction The conceptual idea resulted in a cable stayed structure being the chosen system as it allowed for the appearance of a light structure which hovered over the landscape (NAS 2002). The masts were used to create high elements in the scheme. The system was chosen since the design allowed the structure to be constructed in segments by prefabrication. 13.2 Alternatives The three alternative structural types considered for the roof were: 1- Cable stayed structure with one prominent peak 2- A standard reinforced concrete cantilever 3- A conventional steel cantilever The cable stayed structure with one peak was not seen to be an economically viable solution. The concrete cantilever was considered too excessive in its use of materials. The steel cantilever was seen to have too many inherent problems due to the high wind loads in the area. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 118 13.3 Final Solution The structural system chosen for the roof consists of a steel frame with 100mm concrete slab on permanent metal decking form work. This is then suspended from 35mm steel cables held up by 5 tapered masts and back stayed with 52mm cables to ground anchors. Each mast is pin jointed to a tapered steel column, allowing for rotation during erection. The seating structure chosen was based on an in-situ concrete frame with pre-cast units spanning between the frames to support the main seating. The framing for the seating provides stability for the whole structure and acts as a portal frame in taking the lateral loads. The main in-situ transverse concrete frames are at approximately 8m centers and support in-situ beam and slab construction found at the lower levels as well as pre-cast seating units at the viewing level. Figure 13-1: View of the National Athletics Stadium from East end (Source: NAS 1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 119 13.4 Primary Structural System The primary structural system for resisting vertical loads, arising from gravitational and wind load effects, consists of a cable stayed mast structure, the self weight of the cable suspended roof to resist wind loads and uplift. The vertical loads are taken by the cables which act in tension and these loads are then transferred to the masts and columns which act in compression transferring the loads to the ground. The back stayed cables have extensive rock anchor footings to resist the uplift from the cable in tension. Figure 13-2: View of the masts (Source: NAS 1996) The vertical loads from the seating are transferred from the pre-cast floor panels to the in-situ concrete portal frames. Structural subsystem consists of Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 120 steel purlins supporting a metal deck 'bondeck' with pre-cast seating units. The transfer strategy is based upon cable stayed structure principles, spanning in the shorter direction of the plan, and transferring the loads through cables and masts to the north-west of the stand, maintaining an uninhibited spectator view. The concrete seating structure acts as a separate primary structure and transfers its loads to its own footings through a system of portal frames. Typical Grandstand Section Figure 13-3: Cross section of the grandstand, looking at the joints (Source: NAS 1996) There are two main load paths for the structure. One arises from the loads from the roof, the other from the loads from the seating. The loads applied to the secondary structure of the roof are transferred to the primary steel frame. 3-Way pin p in t Brack fojsfe Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. These loads are then transferred at select points to the tension cables. The loads are then taken in tension up through the cables to the mast. The masts then take the loads in compression down to the ground. Some of the load is also taken in tension by the back stayed cables anchored into the ground. The mast is pin jointed where it meets the tapered steel column which in turn is pin jointed at its base. The steel tapered column is braced to the concrete seating structure. The load paths for the seating structure are taken from the pre-cast seating modules to the in-situ reinforced concrete portal frames. These take the loads down to the piers. Fwtuse Lai Parfe PRACTICE A!i£A Figure 13-4: Site plan (Source: NAS 1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 122 13.5 Secondary Structural System The secondary structural system for transferring loads, arising from both gravitational and uplift effects; consist of a roofing system comprised of a steel frame, metal deck roof with a 100mm concrete topping. The strategy adopted is to transfer the load applied on the roof slab through the steel frame roof support system, this takes the load to a number of discrete points where the load is then transferred to the primary structural system. The load path is taken by the steel purlins and beams that are supporting the 100mm concrete slab. : Deae? loads Wind Loads Typical G randstand Section Figure 13-5: Identifying the types of Loads (Source: NAS 1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 123 13.6 Cable Stayed Structure The cable stayed structure supports a roof 112x20m approximately. It consists of five mast structures at 24m centers. These masts are connected with a three way pin joint to the primary roof beams and the tapered steel columns. The roof cables support the 650 ton weight of the roof. The roof cables are 36mm in diameter whilst the back stayed cables are 52mm in diameter made up of 37x7mm cables . There are two back stayed cables for every mast and nine roof cables supporting the suspended roof. The masts are hinged at their feet to columns attached to the rear wall of the stand thus permitting them to be rotated in a plane perpendicular to the stand. t 1 1 Typical Gmndsismd Section Figure 13-6: Dead loads (Source: NAS 1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 124 The rectangular hollow steel beams forming the stand roof were erected in their final positions on temporary supports resting on the concrete frames of the seating structure below. The 100mm concrete topping slab was then poured onto metal decking which was fixed to the roof framing and acted as permanent formwork. This acted as dead weight to overcome uplift forces in high winds. Once the concrete slab had cured the precut roof cables were connected at each end to the mast heads and roof beams. The masts were tilted forward, then the back stayed cables were fixed to the mast heads which in turn laid back to their final positions, allowing the lower ends of the back stay cables to be connected to the ground anchors. The back stayed cables were then tensioned in pairs to their design forces causing the roof cables to assume their design loads lifting the roof off their temporary supports. Figure 13-7: View of Masts from Seating Area (Source: NAS 1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 125 13.7 Roof Frame The roof frame consists of primary steel beams spanning approximately 20m pin jointed where they meet the masts and columns. These primary steel beams form part of the steel roof frame that holds up the metal deck that supports the concrete topping. Penetrations through the concrete topping allow casting connections along the steel roof frame for the tension cables suspending the roof. The roof ends are braced to concrete structure to overcome lateral and uplift forces. A concrete up stand along the roof edge alleviates roof flutter. 13.8 Tension cables The roof cables consist of 19x7mm wires forming a cable of 36mm diameter. There are nine roof cables for each mast supporting the roof which are in turn balanced by two back stayed cables anchored to the ground. The back stayed cables are comprised of 37x7mm wires forming a cable of 52mm diameter. These can take a load of up to 600-700kN. The back stayed cables are connected to rock anchors via castings which are taper holed and consist of epoxy , ball bearings and zinc dust. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 126 13.9 Footings The ground condition consists of clay going down to mudstone. The footing system consists of 2500x2500mm concrete post tensioned ground anchors which are unsheathed for the first 7m below ground and sheathed for the following 8m. The strategy adopted is that the post tensioned rock anchors act as friction piers resisting the uplift forces from the tension cable. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 127 Chapter 14. Inmos Microchip Factory, New Port, South Wales 14.1 introduction This structure was based on the principle of two pairs of closely spaced masts positioned on the opposite long sides of a basic rectangular spatial/structural cell (Harris & Li, 1996). When repeated laterally, this arrangement results in a long building with pairs of masts defining a ‘spine’ along its center line. This is not only useful for movement and servicing but also as the armature of an ‘open form’ for future extension. Figure 14-1: Inmos Microchip Factory (Source: Hunt 2002) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 128 Firms and offices involved: Architectural Design Richard Rogers Partnership Structural engineering: Anthony Hunt Associates Contractor. Laing Management Ltd 14.2 Chronology 1982 - Structural Steel Design Award 1983 - Eurostructures Award for Architecture 1984 - Institution of Structural Engineers Special Award Figure 14-2: Prismatic Truss (Source: Hunt 2002) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission 129 14.3 Background Inmos is a micro chip fabrication complex, incorporating research and development, the processes of which dictated a building of high service intensity (Anthony Hunt Associates 2002). Funding came from the Government sponsored National Enterprise Board. Information from the soils investigation showed the site to be gravel overlaid by silty, clayey sand. The upper stratum varies in depth between 1.00 and 3.00 meters. Water was encountered at approximately 1.50 meters below ground level. Trial excavations were undertaken and the sides ‘flowed’ preventing deeper excavation. Figure 14-3: Looking at the central spine (Source: Hunt 2002) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 130 14.4 Structure The basis of the structure is the formation of a central spine as the major load carrying element off which a single storey structure is hung on each side forming an umbrella for all activities, with the deep lattice of this roof structure providing a zone for duct work (figure 14-3). The spine not only carries the major structural loads but also houses the majority of the services plant within its two upper levels. Figure 14-4: Frontal Section looking at the central spine (Source: Harris & Li 1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 131 On either side of the spine the offices and clean room facilities are housed in a column free area approximately 40m x 105m (figure 14-4). From the tops of the masts, tension stays are used to reduce the spans of the main beams on each side of the spine. In relation to the width of the spine, the outward cantilevers of the main beams are larger than usual so that their end support and stiffening requires careful consideration. Inmos required a building for microchip manufacture, research and development, together with offices and a restaurant (Harris & Li, 1996). Most importantly, the brief specified a Class 100 clean room, implying a higher servicing intensity and maximum flexibility both during installation and thereafter. In response to this, the key feature of the plan is the location of the 3000 m2, unobstructed clean room on one side of the movement and servicing spine, balanced by the other accommodation, (separated by one open, landscaped bay) on the other. The main plant loads along the length of the building are carried by a multilevel spine formed by the pairs of twinned masts, cross braced in both vertical planes. On each side of the spine, the 36m span prismatic trusses are tension assisted at the one-third and two-third points along their span Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. (figure 14-5). This exposed lattice roof structure is the upper services distribution zone, and supports an under slung roof system. Figure 14-5: Frontal Section looking at the office areas (Source: Harris & Li 1996) Figure 14-6: Plan of the facility (Source: Harris & Li 1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 133 Chapter 15: Case Studies - Suspended Systems 15.1 M e sse h a iie 26 in Hanover, G erm an y Owner: German fair, AG Hanover, Germany. Architect: Thomas Herzog and Partners. Engineers: Schlaich Bergmann Und Partner (Janberg 2000) Figure 15-1: Messehaiie 26 (Source: Janberg 2000) Messehaiie 26 is one of the most innovative structures of the Trade fair in Hanover. It is a culmination of aesthetics and presents a unique typology of buildings where the form complements the style of construction and emphasis is laid on achieving this with appropriate use of materials (Bauen Mit Stahl 2001). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 134 It was important to retain the theme of the Trade Fair, which is “ harmony between humans, nature and technology” and the structure hence is an amalgamation of function, planning and ecological issues. The spacious exhibition areas are column free, covered by a large yet light suspension roof, and with an area of over 28,500 square meters it is the second largest structure on the Fair ground. Light is permitted into the structure by means of a large installation set in the roof which behaves like a large reflector and at the same time generates interesting lighting patterns onto the floor. To make the overall design more sustainable, special emphasis was S aid on the HVAC and hence, the system s i Figure 15-2: View of entrance area (Source: Janberg 2000) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 135 is planned such that only fifty percent of the cooling is performed by the innovative ventilation system. This is achieved by incorporating the right balance between the mechanical and natural ventilation systems. Figure 15-3: Skylight Figure 15-4: Skylight (Another view) (Source: Janberg 2000) (Source: Janberg 2000) 15.2 Messehalle 9 in Hanover, Germany Owner: German fair, AG Hanover, Germany. Architect: von Gerkan, Marg und Partner Engineers: Schlaich Bergmann Und Partner (Janberg 2000) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 136 The Messehalle 9 was completed in 1999 and it has the largest span compared to the other installations on the fairground of the Deutsche Messe AG in Hanover (Schlaich Bergmann Und Partner 2000). Figure 15-5: Messehalle 9 (Source: Janberg 2000) The structure is located along the main axis "Messeschnellweg" across the EXPO 2000s central plaza and the cable roofs are symmetrically placed along the same. The hall 8 is a solid monolithic concrete structure, and conversely hall 9 has a cable-roof, covering an area of 238 x 138 m2 with glass and steel as the materials giving it a semi-transparent skin. 2 . Five main girders spanning 138m following the principles of a back-anchored suspension bridge are arranged at a distance of 45m. They support transversal cable-trusses at a distance of 15m which are connected to the stiffened lattice girders. Five main girders span the overall length of 138m following the principles of a back-anchored suspension bridge and are Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 137 arranged at a distance of 45m off center. These girders support transversal cable-trusses placed at 15m which are in turn connected to the stiffened lattice girders. Figure 15-6: View of entrance area (Source: Janberg 2000) One of the important design issues was to make the structure appear light and airy; hence the space is column free permitting ample amount of daylight through large glazed openings along the shorter side of the structure (von Gerkan, Marg und Partner 2002). The single story hall has an overall area of 185.6 x 116 meters. The roofing system consists of eighteen 122 meter span steel beams. These steel beams are attached together by corrugated steel Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 138 roof panels placed across the longer side of the facility. The panels in turn are held together by lens shaped hollow structural elements. These elements are arranged in such a way that they may be accessed for maintenance or assembly/dismantling the system. Roof light sheds are placed in between these hollow elements. The over assembly was planned such that factory-ready prefabricated elements were assembled on site thereby reducing construction time, with the construction phase starting from the foundations, erection of the support elements with girders placed at 10.8 meters axially and finally the roof panels. 15.3 JAT Hangar, Airport of Belgrade, Serbia, Yugoslavia Employer: Yugoslav Airlines - JAT Designer: The Institute for Material and Structures of the Civil Engineering Faculty, University of Belgrade and the Designing Bureau of GP "Rad". The structure is made of three pre-stressed main roof girders, spanning 135.80 meters and a boom of 9.70 meters placed along the longer side of the structure supported by six main reinforced concrete piers (YUBuild Group 2001). The main roof girders are spaced at 22.40 meters off center, and on Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. both ends are freely supported by two reinforced neoprene bolsters, placed over the beam on top of the main pillars. Figure 15-7: JAT Hangar (Source: Janberg 2000) The upper, reinforced concrete band is a rectangular cross section of 4.00 meter x 2.80 meter, with slab thickness varying from 35 centimeters (at the top) through 20 centimeters. The bottom band system consists of 27 polygonal cross section cables of 11 ropes, each with a diameter of 15.2 mm. Each cable is covered by a protective polyethylene tube and the polygonal cross section of 11 ropes is formed by seven pyramidal steel pipe “ chairs” (YUBuild Group 2001). Rollers are used to support to provide separate Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 140 rotational bearing so as to trigger a considerable decrease in the friction coefficient whenever the cables move. The main pillars are 36 meters high and each one is made up of two parallel bands with cross section dimensions of 60 centimeters by 300 centimeters placed at 4.2 meters center to center. The roof deck consists of a prefabricated ceiling hung from the main girders via a system of steel suspenders, such that energy consumption is minimized and the microclimate in the hangar is maintained. This happens since there is minimum usage of the useful volume and the fagade is kept to a bare minimum. The hung roof construction is also composed of a system of double band reinforced concrete girders with reinforced concrete binding rafters placed over them. The design was selected in a competition over conventional steel structures since it offered reduction in energy consumption I Figure 15-8: JAT Hangar (Source: Janberg 2000) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 141 and maintenance. The prestressed concrete girders are authentic solutions that have been adopted as ideal engineering solutions for spans exceeding 250 for their economic as well as technical soundness. 15.4 Mungersdorfer Stadion, Cologne, North Rhine-Westphalia (Germany) Part of: Fifa World Cup 2006 Architect: von Gerkan, Marg und Partner Engineers: Schlaich Bergmann Und Partner Figure 15-9: Model of Mungersdorfer Stadion, Cologne (Source: RheinEnergieStadion Koln 2002) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 142 The City Council of Cologne decided in 2000 to convert the Mungersdorfer stadium to a modern and fully functional football stadium (Ok-Deutschland- 2006 2002). In June 2001 the jury decided to accept the proposal from Gerkan, Marg and partner/Aachen Hamburg. FC Cologne in the year 2001 took place on 20 December 2001 the first cut of the spade (RheinEnergieStadion Koln 2002). The play enterprise is continued during the construction period; 30,000 spectator places must remain guaranteed. The proposal consists of four piers or masts from which cables are suspended akin to bridge construction. The masts contain two sets of cables, one from which the roof is suspended and the other which stiffens the deck. For every corner a set of stay cables are introduced to stiffen the deck and prevent rotation. These stay cables pass between the two suspension cables which support a central spine with roof decks that are supported along the outer side and cantilevered on the inner side. The deck consists essentially of girders which are juxtaposed on the side of a central spine. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 143 Figure 15-10: Model of Mungersdorfer Stadion, Cologne (Source: RheinEnergieStadion Koln 2002) The proposal consists of four piers or masts from which cables are suspended akin to bridge construction. The masts contain two sets of cables, one from which the roof is suspended and the other which stiffens the deck. For every comer a set of stay cables are introduced to stiffen the deck and prevent rotation. These stay cables pass between the two suspension cables which support a central spine with roof decks that are supported along the outer side and cantilevered on the inner side. The deck consists essentially of girders which are juxtaposed on the side of a central spine. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 144 Figure 15-11: View of the canopy and roofing system (3D model) (Source: RheinEnergieStadion Koln 2002) 15.5 David L . Lawrence Convention Center, Pittsburgh, Pennsylvania Architect: Rafael Vinoly Architects Company: Brayman Construction Company Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 145 The David L. Lawrence will be the first of its kind in the United States; a ‘green’ convention center, an environmentally intelligent facility overlooking the Pittsburgh river front (Pgh-conventionctr 2001). Figure 15-12: View of Convention Center (3D rendering from proposal) (Source: Pgh-conventionctr 2001) The convention center is designed so as to maximize the usage of natural ventilation, day lighting, minimize wastage of water and function as an energy efficient installation. The convention center, located in the heart of downtown Pittsburgh will triple the space available in Pittsburgh for prospective meetings, conventions and exhibitors (PlanPittsburgh 2001). The facility will provide 330,000 square feet of exhibition space (250,000 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 146 square feet of which is column-free), 53 meeting rooms, 37 loading docks, and a 34,000 square-foot ballroom. Figure 15-13: David L. Lawrence Convention Center (Source: Pgh-conventionctr 2001) The convention center will house two halls, a main and a secondary with meeting rooms, two lecture halls, a 33,000 sq. feet Ballroom and a parking garage for 700 vehicles. The construction management process is being handled by AMEC Construction Management, Inc. a global engineering consulting firm. The cable suspended roof and the 4 ft. by 10 ft. clerestory walls along the sides of the building are designed to be flexible; surrounded by silicone sealant gaskets and sleeved around the cables such that the outer skin can actually breathe thereby allowing ventilation. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 147 Figure 15-14: David L. Lawrence Convention Center (Interior view from proposal) (Source: PlanPittsburgh 2001) 15.6 Glass Canopy for a Light Rail Station (Stadtbahnhaltestelle), Heilbronn, Germany Owner: City of Heilbronn Architect: Auer + Weber, Stuttgart Engineer: Schlaich Bergmann Und Partner The glass canopy over the tram and bus station in Heilbronn has proven to be one of the most innovative and creative design elements in the realm of overhead glass structures (Dupont Benedictus 2001). When construction started on the proposed design, there were no standards set for such a Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 148 structure, the first of its kind in Germany. Before the actual fabrication, a variety of tests and experiments were performed to study the behavior of the medley of glass, nodes and support pads when loaded fully along with extensive wind tunnel testing to verify and study the soundness of its aerodynamics. Figure 15-15: The completed canopy at Heilbronn (Source: Architecture Week 2001) The concept chiefly was to provide shelter in the most transparent way and as a result, the canopy offers high load bearing capacity, even for partially damaged glass and sufficient weight to resist uplift in the strongest of wind currents. The 210 panels of glass each measuring 6.4 feet by 6.1 feet form a Reproduced with permission of the copyright owher. Further reproduction prohibited without permission. 149 continuous, slightly curved, smooth roof surface and are suspended from a set of stainless steel cables stabilized by its own weight (figure 15-16). j a i ; 0 - . . ’ ; ..i ■ Figure 15-16: Glass nodes and pads supporting the glass (Source: Architecture Week 2001) Each glass panel is made up of three layers, each layer being 0.4 inches thick and all exposed edges of the panels along the periphery are covered with stainless steel sections (Architecture Week 2001). Extensive testing was carried out to ensure the safety of these panels and support nodes under maximum load conditions. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 150 Figure 15-17: Support Pads (Source: Dupont Bened ictus 2001) Figure 15-18: The Canopy (Source: Dupont Benedictus 2001) 15.7 Golden Gate Bridge, San Francisco Chief Engineer: Joseph B. Strauss Consulting engineer: Leon S. Moiseiff Figure 15-19: Golden Gate Bridge (Source: Janberg 2000) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 151 The American Society of Civil Engineers has named the Golden Gate Bridge one of the “ Seven Wonders of the Modern World”. The bridge opened in 1937 spanning a total length of 8,981 feet and a main span length of 4,200 feet making it one of the largest single—span suspension bridges ever built. The two massive towers of the bridge are the largest in the U.S., at 746 feet above water and the deck has a clearance of 220 feet. Construction of the bridge commenced on the 5th of January 1933, with digging of the foundations around the hill sides for the deep set anchorages that would support the concrete pylons. \ I 5 Vi Figure 15-20: Suspenders (Source: Janberg 2000) Figure 15-21: The Bridge (Source: Janberg 2000) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 152 The construction of the South Pier was particularly difficult due to the strong tides and heavy swells. The South Pier is the keystone of the structure and this required excavating 65 feet in hard rock below the water surface. The anchorages are made of more than one million tons of concrete which support the anchorages of the bridge (PBS Online 2001). The North pier was built easily on a bedrock ledge 20 feet below water level. A water tight cofferdam big enough to house a football field was built on the Southern San Francisco side to construct the pier. The towers were complete by 1935 and the bridge was completed two years later. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 153 Chapter 16: Case Studies - Stayed Systems 16.1 McCormick Place Exhibition Center, Chicago, Illinois (USA) Architectural Design: Skidmore Owings and Merrill Figure 16-1: McCormick Place Exhibition Center (Source: SOM 2000) The first addition to the McCormick Place Exhibition Center, designed by Skidmore Owings and Merrill, was completed in 1986 and it was the largest facility of its kind in the United States (SOM 2001). The facility consisted of a cable stayed system grid employing structural steel over an area of 1.5 million square feet (130,000 square meters), thereby providing column free Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 154 spans. The designed system also corresponds to the site constraints related to the existing active railroad right-of-way below the expansion. I If p . Figure 16-2: View of Masts (Source: SOM 2000) The design consists of an upper exhibition hall with an area of 750,000 square foot (70,000 square meters) which is the most distinctive feature of the installation and was completed in 1970. The roof above it consists of a system suspended with cables supported by twelve concrete pylons on a 120 foot by 420 foot (37 meter by 75 meter) grid. As the facility expanded, Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. additions like a lower exhibition hall, pre-function areas for halls, visitor and food services and facility support spaces were implemented with special emphasis on importance to building systems, flexibility and efficiency of move-in and move-out. Figure 16-3: View of Interiors (Source: SOM 2000) The third phase was completed in 1996 by A. Epstein & Sons International, Inc., with a new exhibition hall consisting of one million square feet of exhibition space in addition to another one million square feet of support facility space. The new extension also encloses 30,000 square feet of additional meeting space, expanded conference and food service facilities achieved by renovating the original hall. McCormick Hail today has over 2.2 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 156 million square feet of Class A exhibit space making it one of the largest exhibition centers in the United States. 16.2 Hillsboro Stadium, Hillsboro, Oregon (USA) Architectural Design: GBD Architects Structural Engineering: KPFF Consulting Engineers Figure 16-4: Hillsboro Stadium (Source: GBD 2001) The Hillsboro Stadium in Oregon was a project that was designed with several constraints varying from a tight budget, schedule requirements as well as innovation in design (GBD Architects 2001). The site excavation work had commenced when the design build contract was awarded in mid Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 157 Reproduced with November of 1998. The design emphasized on prefabrication to facilitate the minimizing of site staging and allowing site work to continue. The various steel support towers, steel roof panels and guard rails were fabricated offsite, at the same time as the foundations were being poured. Figure 16-5: Hillsboro Stadium Figure 16-6: Mast (Source: GBD 2001) (Source: GBD 2001) The 4000 seat stadium was built in only 7 months, just in time for the high school football season and the facility was instantly liked by the public and the media (Hoffman Construction Company 2001). The approach consisted of a component by component approach due to the schedule constraints. The roof for instance was assembled on ground and lifted and placed in permission of the copyright owner. Further reproduction prohibited without permission. sections. The stayed system is supported by 200 connecting rods attached to fours steel towers. The total area about 168,000 square feet, and the steel-framed, pre-cast concrete stadium has the world’s largest single piece of artificial turf at the time of its installation. Figure 16-7: Hillsboro Stadium (Source: Hoffman 2001) The facility is equipped with locker rooms, concessions and press boxes, and hosts soccer, baseball and softball games as well as music concerts (KPFF 2001). The seating is fabricated using pre-cast concrete planks supported by structural steel beams and columns. The area below seating is used for rest rooms, concession booths, team locker rooms, and ground maintenance as well as storage facilities. The $7.4 million project was completed in August Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 159 1999 less than a year of the contract and it was commissioned by the City of Hiilsboro Parks and Recreation Department. The roof sections are separated with translucent decking corresponding to the support towers and the access isles below. The American Institute of Steel Construction Engineering Award of Structural Excellence was presented to the Hillsboro Stadium in 2000 for projects under $10 million. The stadium was also selected for the 2000 Outstanding Project Award by the National Council of Structural Engineering Associations (Janberg 2001). 16.3 Toyota City Stadium City of Toyota, Aichi, Japan Designer: Kisho Kurukawa Architect and Associates Consulting: Over Arup and Partners (Janberg 2001) The site for the Toyota Stadium was chosen adjacent to the Toyota Bridge to commemorate the 50t h anniversary of municipalization of the City of Toyota (Kisho 2001). The Toyota Bridge is one of the key bridges in the main pedestrian based road system of the City of Toyota. The design confirms to the strict protocols laid down by FIFA and the roof was designed to permit Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 160 natural light on the lawn and yet it encloses all the main stand seats even when the roof is opened. Figure 16-8: Toyota Stadium (Source: Kurukawa 2001) Figure 16-9: Toyota Stadium (Interior) (Source: Kurukawa 2001) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 161 The design of the wings of the suspended roof is like the traditional shape of the Japanese roof and has been designed parallel to each other to enable the movement of the light weight roof along the rails by air-pillow method akin to the Japanese fan for closing and opening. The entire construction is in steel covered with fire proof pre-cast slabs enabling reduction of the overall weight of the building structure (Taiyokogyo 2001). In plan the stadium configuration is circular, with the outside edge profiled like a sine curve. This is achieved by raising the east and west side of the seating and lowering the north and south parts on the sides of the goals. Kurukawa justifies this profile as a means to permit sunlight for the grass. The profile also suggests the force flow in the suspension mechanism. The curvilinear profile is formed by a row of concrete columns (a colonnade) of varying heights complementing the roof. Figure 16-10: Retractable Roof (Closed) Figure 16-11: Retractable Roof (Open) (Source: Taiyokogyo 2001) (Source: Taiyokogyo 2001) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 162 “ The ‘retractable folding air-mat roof, the last large-scale device, finishes this rare stadium as a vessel for surplus” (Taiyokogyo 2001). The roof is opened by inflating its air mats one after another akin to a satellite which unfolds its solar batter arm. Figure 16-12: Retractable Roof (Detail) (Source: Taiyokogyo 2001) 16.4 Train Station "La Plaine-Stade de France", Saint Denis (France) Architects: Jean-Frangois Blassel, Jean-Marie Duthilleul, Etienne Tricaud Designer: SNCF - Agence des Gares Engineers: RFR Consulting Engineers & SOGELERG (Janberg 2001) The new station of the Saint-Denis Plain stands as an icon in the City of Saint Denis while catering to significant flow of travelers and offering a new identity to the urban fabric (RFR 2000). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 163 Figure 16-13: Train Station "La Plaine-Stade de France", Saint Denis (Source: RFR 2001) The station designed by Jean-Frangois Blassel consists of a unique roofing system employing a light metal frame and glass and wooden panels. The facility is built along the existing railway line and continues until the intersection of the axis of a mall allowing direct access to the station. The structure encompasses of a frame of stayed masts which support the roof and the roof in turn shelters the pedestrian zone for travelers. This facilitates column free space in the quay allowing passage for large crowds during peak hours. The central mast carries the vertical loads transmitted by Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 164 the stays and continuous unblocked areas are achieved as suggested for railway lines. m m Figure 16-14: Train Station "La Plaine-Stade de France”, Saint Denis (Source: RFR 2001) The 50 m long modular framework was transported in one piece and assembled on site within a few hours. The pre-stressed external stays which stabilize the structure vis-a-vis with the side loads and the ties contribute significantly to the design. The modules are essentially suspended using rods from the central mast which in turn is designed to counter large rotational forces at the bottom. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 16-15: A typical module (S ource: RFR 2001) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 166 Chapter 17: Compiling the Disc 17.1 introduction to the Contents The succeeding stages following data collection consist of organizing the data based on the structure deduced in the preceding chapters. Once this stage is complete, the authoring starts. The authoring consists of setting up links to navigate within the chapters and within the tool or between chapters. The interface design, navigation loops, videos, as well associated scripts in lingo are discussed in this chapter. 17.2 Designing and Authoring the Navigator The first step in designing the interface was to define what kind of links would be required on each page. This means that the basic ‘Navigator’ had to be designed and authored to function with working links. The buttons were designed in Adobe Photoshop with emphasis on mouse-over effects to provide visual cues as to where the user is in the tool; as well as to provide a user-friendly appearance. The following buttons categorized for Primary Loops are the most frequently used: ® Next Page (figure 17-1) • Previous Page (figure 17-1) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 167 Next Chapter (figure 17-1) Previous Chapter (figure 17-1) % % Next Page Next Chapter Previous Previous Page Chapter Progressive Step Button Figure 17-1: Navigation Buttons (Primary Loops) Additionally, there was the need for another button, titled ‘Progressive Step’. This button is added to help the user to navigate (forward navigation only) one step at a time since every page consists of subordinate elements. A good example would be where Page One is a complete Case Study with three screens, each one describing individual topics of structure, design firm/architect involved and architecture, respectively. The ‘Progressive Step’ button loads each topic. For instance, if the Case study of the Golden Gate Bridge is being discussed, the first part to load will convey information about the engineer and some facts about the structure like overall span, time line, Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 168 etc (figure 17-2). When the ‘Progressive Step’ button is engaged; the second part containing more structure specific page will load (figure 17-3). iP liiliiii Figure 17-2: Page Screenshot Subsection One Figure 17-3: Page Screenshot Subsection Two A consistent template is used throughout the application. Each page contains subordinate topics. This pattern proved to be useful in creating a generic navigator and hence the scripts could be made generic while the interface also remains constant. Two more buttons, under ‘Secondary Loops’ that link to the Table of Contents and the Index were made (figure 17-3). ^1 H e lp T a b le o f Menu C o n te n ts B u tto n B u tto n Figure 17-4: Navigation Buttons (Secondary Loop) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 169 17.3 The Graphical User interface (Phase One) The design of the graphical user interface was carried out in three stages. In the first stage, once the buttons for the navigator were made, a work area of 1024x78 pixels was decided. The reason for choosing this resolution is that most monitors today have a minimum screen resolution of 800x600 or an ideal case of 1024x 768. The basic navigator has the set of buttons described earlier (figure 17-5). Next, to make navigation easier, a few more components were added to the Navigator. This included a page by page link with dropdown menus identifying where (chapter or page) the user would be at any given time within the tool. M a * n T o p i c H e r e Figure 17-5: The Navigator The ‘hyper jump’ (H-J) button was intended to load all the elements on a page. The hyper jump has been eliminated in the latest version. The shortcomings of the interface in the first phase were that the areas occupied by the navigator and video controls were large and hence, the space available for displaying data was limited. Secondly, the dropdown menus Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 170 were difficult to access at the secondary level, for instance to access a page (menu level 2) within a chapter (menu level 1). m '.s<ar^m £& d to y fcvsteir® t.«-, oy i sjs« cnw ?<$* aoi lyp* < 6 stock*# (r»m&rx ^iC>r sa^jjru If TH* *6v?tef5i resist s i! !& <k& a rrs l i*v g ■ u s -is , wNcn isTphge er (f» iu tk fo j t W ja s *3 W s riS so the roan i as c.uic** *.ik5 directly ixsriSte, Figure 17-6: The Complete Interface (Phase One) 17.4 The Navigation Loop A typical navigation loop consists of three basic levels (figure 17-7). The top most level contains the Table of Contents Menu, the Help Menu and the Front Page. The second level of loops consists of all the Chapters, organized in a linear format with interlinking to different parts within a chapter. The third and final level of loops consist of links embedded within a chapter that allow a user to browse from within a chapter to a part within Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 171 another chapter or to the levels which are placed on the primary or secondary loop level. H i ■ M i Mailt flM M r T Figure 17-7: The Basic Navigation Loop The tertiary level of loops is usually provided in the form of links at the end of each chapter (figure 17-8). These loops are links provided for cross examining topics related to issues discussed in a particular chapter. For instance, if the chapter in question is the introduction to strands and wire- Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 172 ropes, links are provided to pages which describe ASCE guidelines for cable structures, additionally to parts of the tool which discuss cross-section area calculation and also to the chapter which covers the Vector Graph Method. Such links are provided as buttons, unlike some parts of the navigator which are hyperlink text entries. T.A!k* ni Gum-ms ♦ Figure 17-8: The Tertiary Level Navigation Loop Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 173 17.5 The Graphical User interface (Phase Two) In the second phase, the GUI was changed completely. Since, the first phase of the GUI proved to be insufficient in providing ample space for the data, a new GUI was developed. This means that color schemes, the location of the navigator as well the format to display data were reworked. Additionally, the system of linking from each page and the areas determined to display were changed. The concept of using drop down menus was eliminated and text based hyperlinks were added. The navigator was placed at the top left corner (figure 17-9). The main topic would be displayed on the right hand side of the tool while the text would be displayed using ‘fields’ with the option of scrolling. At this time, the tool was named as ‘Instrucktor’. Figure 17-9: New Location of the Navigator Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 174 The display area was bifurcated into two subsets, the left half for displaying the text (figure 17-10) and the right hand side for displaying images and videos (figure 17-11). After more analysis, it was determined that the navigator needed to be more conspicuous in the overall GUI with emphasis on using clear notations describing the functions of the buttons. Also, the amount of space left on top could be used to increase the display area (figure 17-12). Figure 17-10: Text box Figure 17-11: Image Display Area The Progressive step button was also a part of the navigator, but its location was changed since this button would be the most used and it was desirable to locate it away from the main display area, so that the user could this way minimize the use of the mouse. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 175 Figure 17-12: The GUI (Second Phase) 17.5 The Graphical User Interface (Phase Three) In the third phase, each individual element was worked on and made to appear 3 dimensional. The display area was expanded by eliminating the blank space on top. The Primary navigation buttons were changed but restricted to the same area of the GUI, while the ‘Progressive Step’ button was placed at the bottom right corner of the interface. Additionally, new sets of text based links were introduced at the top (figure 17-13) and bottom of each page in the tool to provide easier navigation within a chapter (buttons on top) and to the table of contents at the bottom (figure 17-14). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 176 The flowchart deduced for navigation in the first case applies to this GUI as well (figure 17-7). The size of the buttons was reduced, but the scripts and links are the same. . " '■ — ■ Figure 17-13: Top Navigation Buttons (secondary) images ism m m s M itte < ! s Figure 17-14: Bottom Links (tertiary) The position of the text box as well as the images remains the same, but the areas occupied for the images are increased as opposed to the GUI from the second phase. Lastly, additional fields have been introduced to accommodate the interactive 3D models with controls to view and test them. More buttons for playback Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 177 and operation of video clips as well as mouse and keyboard entry modules were introduced. Navigate within Things itt 4te¥f§ate within the tool f,n '■Zii-rf&'vs « < '& reqinetffhf i ortetfooon . h4ngsy a #a trtz ?o tht & ” 4n i& < & . y, iTfeSBTi- \i, <w ety i/ub hi the < « • i^.-io^ry n mswe wmps o the iWv, h ? 3 $ |i-j tor^o-n m> itendfn?? « * » o l 1 i;s jy;w*o»ti<.. a f}\n> & th y % '<&>> u- k*vi*JS s t ry« at different tevefc tfifcimitou at H s r jn < f - r te w * s . y v-> .* wiihii = the too! m 3 frogmdsive S:ep >■■■■■■■ Figure 17-15: The GUI (Third and Final phase) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 178 Chapter 18: The Components and Disc Structure 18.1 Introduction The different kinds of file formats imported into director while this tool was being made were from simple * .jpg’s (images or graphics) to complex *.w3D (interactive 3D Shockwave) files. In this chapter, the different file formats are discussed and finally, the structure of the disc in the form of flowcharts is displayed. 18.2 The File formats imported The process of importing files into Macromedia director is simple and the program allows a variety of formats to be used. The files that were used in creating this tool are of the following format: • Pictures, Images, Graphics (*.jpg) • Adobe Photoshop file format (*.psd) • Text and documents (*.txt and *.doc) • Sound files and voice over (*.wav and *.mp3) • Video format: QuickTime and Microsoft AVI (*.mov and *.avi) • Director External Cast (Test) • Director Movie (*.dir) • Interactive Shockwave file (*.w3d) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 179 • Macromedia Flash files (Mia) • Adobe Illustrator Vector Graphic (*,ai) Working with text and sound files is the simplest, while graphics poses additional challenges. This happens when one tries to create an alpha mask I channel. In director the background of an image (if it’s white) can be made transparent and the image can be made to look embedded as a part of the overall background. One of the problems in trying to achieve this is aliasing (figure 18-1). The borders have “ jaggies” or “ stairs” and hence the image lacks smoothness (West 1996). This is done by padding the borders of the image with shades of colors where the jaggies appear. To make the images seem seamless and smooth, antialiasing has to be applied in Photoshop and the same has to be done in Director as well (figure 18-2). Figure 18-1: Aliasing along the borders Figure 18-2: Anti-aliased Image (Source: West 1996) (Source: West 1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 180 In some cases when * .jpg’s are used, if the problem still persists, the resolution of the source file has to be reduced since the work area was too small. For instance, most of the vector graphic diagrams prepared for this tool were made at 300 dpi and then rasterized. Although the image sizes can be reduced in Director, the aliasing may persist. In the event of that occurring, the resolution has to be scaled down and the image size reduced to a more comprehensible scale before being imported into Director. This occurs since recalculating sizes (aspect ratio) of the large images when reduced to relatively smaller resolution can lead to errors and hence, pixelation may occur due to loss of some data. However in some cases, where a *.psd file is imported into the application, aliasing does not occur. In case of video files, the main issue is the encoding format and the codec used. Adobe Premier has several codecs available and the most commonly available one in most Windows based media players are ‘Cinepak’ and ‘Sorenson Video’. These codecs are mainly employed when a movie is being encoded either as an *.avi or *mpg (Mpeg layer 1) video file. Other codecs may be available on some systems, but the players are more likely to perform errors. Hence the option is to use either AVI or QuickTime format. The benefit of using a QuickTime video is that controls also are displayed when the video window loads and hence, secondary sets of scripts to control Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 181 videos are not required. Additionally, QuickTime files run on both Windows based as well as MacOS based systems, which give them an upper hand over conventional video formats. Since, this tool is purely a Windows based application, QuickTime movies are not used. One of the most important file formats that may generate errors at the time of authoring are the interactive Shockwave 3D files. The first problem, that of exporting is of crucial importance. The common errors that occur when the Shockwave engine is used to export a 3D model is that of lights, maps, and textures not being exported in the model. This occurs due to the fact that when materials are applied to 3D objects in SDSMax, generic names like ‘Material #T and ‘Material #2’ are not recognized by the engine. It is advisable to use a unique name tag for every material that is applied. This holds true for all levels of materials (bump, shade, light, etc.) used when working with the Material editor in SDSMax. Also, bicubic samples create problems and are not embedded while the file is being exported. The preferred format to be used for textures is *.bmp (Bitmap) as prescribed by Shockwave. But bitmaps do not give the same effects as generated by jpg’s when bump is applied in a texture. So, if jpg’s are used, the ‘UVW mapping’ option in 3D Studio has to be set to fit the shape of the model instead of allowing the program to decide and restrict the map setting to Planar. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 182 For lighting to be exported correctly, the camera settings have to be tweaked such that the exporting engine recognizes the edges of the shadows created by the light source. Although the light source is immaterial (target spot, target or omni), it is important to make sure that the ‘cast shadow’ option for the light is set to ON. Lastly, before exporting a model using the engine, it is necessary to group the entire object into a single entity, if the author expects to use the model as a single piece. There are two ways of doing this. The first one is to construct the model and group it as one and export the same. This technique is ideal if the model will be treated as a single entity also in director. This is so because, when the model is assigned controls in director, the author has the option of setting different parameters like rotate, pan, camera dolly and axis manipulation based on the imported model (to individual entities or the whole assembly). When the model is used as a single entity, it can have such parameters applied to it as a whole and hence when viewed, the entire model is rendered. If the user wishes to zoom, pan or dolly the camera, the entire model is used to perform the active command. But if the interactive session applies to individual parts of a model, parameters/actions like automatic model rotation, camera orbit, and mouse button triggered model rotation can be applied to individual components. To explain this, an example is Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 183 described below. Consider the model of a Closed Socket application to be studied and provided for interactivity. The entire model can be grouped as a single object and parameters/actions like pan, zoom, camera orbit mentioned afore can be assigned to it (figure 18-3). Otherwise, each of the components i.e. the turnbuckle, the eye-end rod and the concrete anchorage block can have actions assigned to them separately (figure 18-4). It is desirable to set the renderers while in Director as automatic or DirectX 7 or higher. This is a better option since hardware rendering is good only in machines that have 3D accelerator VGA cards. The software rendering option is also available, but on machines with memory lower than 128 MB, the rendering time is more and hence the process may appear jerky. Figure 18-3: Closed Socket Figure 18-4: Closed Socket (Single group) (Individual components rendered) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 184 18.3 Disc Structure The following flow charts have been constructed to describe the content in each chapter. Each chapter was developed as a broad topic with two subtopics. Although these groups actually are not seen in the final product, the technique assists in segregating the topics for clarity. The sub topics are categorized into pages. The final template for the tool consists of four pages with links in each page to different parts of the chapter as well as in between chapters. A ‘page’ does not necessarily mean a page as in conventional terms; it is more like a topic or a group as projected in the flowchart. Each page can contain several parts to it revealed in different screens with linear navigation. Each Chapter has several sets of links based on the level of navigation loops, which has been discussed in Chapter 17. The idea of using the word ‘page’ is justified by the fact that if a term like ‘topic’ was used, this could be interpreted as separate topics, although in fact the entire chapter encompasses only one broad topic. The flow charts clarify the reasoning behind the terminology used. Also, at the of each chapter, the user has the option of downloading a PDF version of the entire chapter to his/her hard drive for future reference or to make a hard copy. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Flow Charts fo r Director £i) Specs tor smooth pigy (ii) introduction to the tool (IB) How to Navigate (iv) How to view VR and Movies ivl Vo;:;:. 0'"'."s {</:) J S!C N’ t-:-:-. {a} Naviagtion vhe :'ome 3;-v:or ■ v!:> ■ J r.fe a (v: I; Ths >lics^sfv Figure 18-5: Chapter Zero V End of ©tajprter I I I Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 186 \ f G R O U P W (i) tqo! ipdex (b ) Tool Specs (ill) Link to Glossary 1 1 G R O U P ‘ S ’ a w a l k : t h r o u g h (i) Concepts of Structures fii) Loading {Typology & Behavior j flli; s=arce, Stress. Strain and Stability (jv) Relevant data IW T It S G R O U P 6 C * A W A :..lt I H i-L I iJ G ? H (i) Notations ili) Essentia'Data (III) Hints C iv) Diagrams M*t* T « t 4 t I liSt# Figure 18-6: Chapter One Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 187 f G R O U P W :■ £ scvo-. I G R O U P ‘8’ G R O U P * B * .>■- j : - : c k r~ C A B L E S ‘ 3 =1 3; -:s (ii) H m o d discussed, span limits oe: iycs . - if i. Z '-ve. -z-;:,=i£ ':s;v-/een. St/arcs. ana vVVs-h.o^e-; ;:l: Ccr'iJBr’s'cns c.- s.’c i s;sr: :m:-s ; i:‘ - "Viet :s Ac & p.- VM* ?» iBifl e f Chapter Figure 18-7: Chapter Two Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 188 \ ©Roupw e a s v e s « s « p # s > g j» s y c t c m b {I) Underlying Physics, Mechanics, Gewtetry and Synergy (if) Typical ©cample - a. Oafles Airport, Wmkingtm b. m m n Sate 'Bri&$4, SPO p i) Additional Data * factors for design, application O P T IO N A L L I N K S Analysts & Design J Case Studies (Suspended Systems) iiAQiaer ASCE Guidelines i i % ,m m to AMUPM* Vector Analysis r OR - Proceed G R O U P * B > (i) Analysis (Theory) (is ) Numeric Analysis (H I) Computer Analysis Figure 18-8: Chapter Three Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. U s-A w Jnioi'si L.iS 'sS "af.'.O'i ii'.r <Ss-.;fi-i. s;i|j-'o&i.or. O P T IO N A L L I N K S 1 Audio V>U8' e x a m p le AiVtyall & Design C . ? se S im Jiei A8CE Guidelines Vector Analysis f Proceed © *i© |stp;V (i) Analysis (Theory) (ii) N um eric Analysis (iii) Computer Analysis Figure 18-9: Chapter Four Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 190 G R O U P ‘ A ’ , WfVPWm O P T IO N A L L I N K S * 1 G R O U P ‘ A * : : W fm t® ; • ■ • W f w tm m : Atice (HMSPMni C A S E S.'s u c u ts t GROUP - f > G R O U P ‘C & ‘D ’ ^|ga: g » g i3 c B a g 5 ll» ' Slppd ft S»sj»«ttwi AGGS GUUMSUMWS : s .'* '' iW M P V ft Figure 18-10: Chapter Five Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 191 I G R O U P ‘ A ’ C A B L E S U S P E N i G O S Y S T E W S I ) © h i -page af ilsta per - : Case-PlB% (!i) Timeline, D a ta , Specs (iii) P h o to s, numbers I f i W H , ■ tW fc ts S lc g I B a c k t o T h e o ry ( C h a p t e r 33 § |B T * W t> M A V iM fg . Back, t d Th e am? (CHAPTER 4 } S IC t-P ® TO COMPARATIVE STUDY C /6 & & Ca s e s t u d y E x a m p l e s dm S t a y e d S y s t e m s S kip t o C o m p a r a tiv e S tu d y 1 P f J O O E E O STOLf 'O S ' CABLE STAYED SYSTEMS > !; One page of data pe? C:3se-.=sudy (itj flmenne, Oats, Specs ','ii- Poole;-. i.um bets S Z A & Z L Btu'£ s - jS l S 3 1 Ba c k T o E x a m p l e s o r S u s p e n d e d S y s t e m s P R O C E E O Figure 18-11: Chapter Six Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. DISTINGUISH (i) Unique features (ii) Data, Specs Scar, lir-iis (iv) Additions! Data D IA G R A M S F IE L D Q U IC K ANALYSIS D IA G R A M S ! (!) Representing Forces <ii) Reactions :::i) Load Psifct ■ ;:v ) Accitic'Ei l's:.a !,v ‘ Concepts { P R O C f it O B a c k c t o A 5 CE SUiOEUNES Figure 18-12: Chapter Seven Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. S t a « p a s ?)S, Co d e Rs-sm.ATtaws C A S E S t u d ie s (Stayed S ys te m s ) iifw sw afe. y«®S Hints, Tips, Code regulations for each case Proceed OR OR C a s e S t u d i e s (Su sp en d ed System s) SUMMARY P A G E ram. M B M X \ * I C h a p t e r 3 ( L i n k ‘ 3*S C h a p t e r 2 ( L i n k ‘a * ! H ¥ « M s Figure 18-13: Chapter Eight and Nine Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 194 A Y A S fe M S W i C h a p t e r 3 C h a p t e r i i s OR C h a p t e r s OR I C h a p t e r •7 C h a p t e r 9 * G l o s s a r y & q u i c k: R e f e r e n c e: Quick links to main stem pages with progression towards relative chapters ASCE G u id elin e s § I ■ Vector A n a lys is INDEX WiTM MNKB Quick links to definitions, examples and terminologies Acknowledgem ents Figure 18-14: Chapter Ten, Eleven and Twelve Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 195 Chapter 19: Packaging the Disc 19.1 Introduction The final product of the research is to be bundled on a compact disc and then distributed. This means that packaging the product is important to market its value and most importantly a single look at the bundle should give the user an idea about its application as well as the content. This chapter looks at the process of bundling the package into a product ready for mass production and finally, distribution. 19.2 The Name of the tool: Process and Conclusion The term ‘Catalyst’ as described in the Merriam-Webster Dictionary, is a noun and: 1: A substance (as an enzyme) that enables a chemical reaction to proceed at a usually faster rate or under different conditions (as at a lower temperature) than otherwise possible 2: An agent that provokes or speeds significant change or action. At the first stage, the tool was called, ‘Instrucktor’ based on the ideology that it will be used to study cable stayed and suspended systems. But the name Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 196 seemed inappropriate and a better alternative was sought. The term ‘Catalyst’ means an element or an entity that decreases the time taken for a given process to be completed. This term can be used metaphorically since it applies to any process, even if it does not imply the science of it. The tool is a supplementary learning medium to course work. This means that the topic discussed can be referred in detail and understood. It ‘expedites’ the learning process with the help of multimedia plug-ins. Hence, the name ‘Catalyst’ seemed appropriate. 19.3 The Logo The logo adapted to underpin the name of the tool is that of an atom. The catalyst is depicted at the smallest level, an atom with its electrons in a state of constant motion (figure 19-1). The logo explains the expedition process graphically. • / ' ' v f . Figure 19-1: Catalyst Logo Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 197 19.4 The Compact Disc Jewel Case The CD Jewel case cover as well as the CD label was designed as a part of the project (figure 19-2 & 19-3). Both the covers are designed with instructions about the tool, minimum system requirements to play the disc and the goal of the project. Figure 19-2: Compact Disc Jewel Case Cover Figure 19-3: Compact Disc Cover Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 198 Chapter 20: User’s Manual 20.1 In tro d u ctio n The product of the research is a compact disc for use on personal computers. Any application available today has a help file associated with its use and helps the user to troubleshoot minor problems. This chapter is the user manual provided for the application, ‘Catalyst’. 20.2 Overview o f the Application Catalyst is a computer aided teaching tool to teach about two systems of construction that share a common material, the high strength steel cable. A high strength steel cable is four to six times stronger than conventional high strength steel, but only twice as expensive. Hence systems like cable stayed and cable suspended are more economical and feasible for large installations. Catalyst has been authored for the Master of Building Science Program at the University of Southern California and is purely for academic use. The application is designed to work with PC’s and for a minimum resolution of 1024x768. It is intended for academic use and is not for commercial Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 199 distribution. The target audiences are sophomores enrolled in the Bachelor of Architecture degree course. Catalyst provides a broad introduction to the concepts of structures, but the user is expected to have some knowledge of the terms used in Structures as well as working knowledge of simple computation to find moments, stress and other such quantities. At the next level, the application introduces the two systems described above with emphasis on the concepts and then moves on to display precedents of each case. Catalyst in no way offers detailed explanations to the design and analysis of these systems by the numerical method. The emphasis is on the Graphic Vector Analysis Method which is also discussed from the basic level as the application progresses. The user has the option to save material at the end of each chapter in PDF format. All the material in this application has been copyrighted and is used for educational purpose only. None of the content may be reproduced without prior permission of the author. 20.3 Minimum System Requirements Catalyst is a PC based program. It has been authored using Macromedia Director and hence, the Shockwave Player is required to run the application. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 200 The Shockwave Player is available at the Macromedia website and can be downloaded for no charge with prior registration. Additionally, DirectX 7 or higher is required to play the animation and view the interactive 3D models. All system requirements are summarized below. • Windows 95/98/98ME/2000/Xp • Pentium II 266 MHz or higher • 32MB RAM or higher • Double-Speed CD-ROM drive (8X+, read) • Local Bus SVGA Video Card (Direct X Compatible) • Minimum Screen Resolution of 1024x768 pixels • 32-bit Color depth, 24-bit Sound • Microsoft Direct X 7.0 or higher • Macromedia Shockwave Player, required 20.4 Getting Started Catalyst is a very simple application to use. When the CD is loaded into the drive, the application will run automatically. If Shockwave is not installed on the system, a message window to install Shockwave will be displayed. This link may be followed to access the Macromedia site and download a copy of the installation. The Shockwave player is installed remotely and Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 201 downloading the executable installation is not possible. If for some reason the disc does not play, the CD drive may be accessed and by double clicking the ‘Catalyst.exe’ the contents may be loaded. If the user has installed a Microsoft Power Toy like TweakUl, it would be desirable to ensure that the “Play data CDs Automatically” field is checked under the Paranoia tab in the TweakUl program. Once the CD loads, the program runs in full screen mode and the Escape Button maybe used at any time to exit the application. If the resolution of the monitor is less than 1024x768 pixels the application may not play smoothly. If the resolution is higher than 1024x768, the application will play in full screen with a blank screen border around the active window. CHAPTER T W d > In t r o d u c t io n CHAPTER THREE 'HARTER FOUR - S ta y e d g tru c fc iu F igure 20-1: Table of Contents Screen Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 202 The first screen to appear is the Welcome Screen with a brief video introducing the authoring company, “Involution UnLimited” and a video about Catalyst. The user may skip these parts by engaging the Skip button, located at the right bottom corner of the screen. The second screen to load is the Table of Contents (figure 20-1). The table of contents (TOC) can be used to navigate to pages with different chapters and the subheadings under each chapter. Or the user has the option to click the ‘Start’ button to proceed using linear navigation. Engaging a link on the main TOC page will load the second set of pages in the TOC which contain Chapter Index page (figure 20-2). I I CHAPTER' THREE - S u s p e n d e d S t r u s t u ' CHAPTER' FIVE CHAPTER. SEVESJ C o m p a r a tiv e S tu d y CHAPTER EIGHT - S ta n d a r d s Figure 20-2: Table of Contents Screen (Chapter Index Page) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 203 The Chapter page has links specific to different topics under the active chapter. The user may identify the Chapter index page by locating the chapter name on the top left corner below the TOC link (figure 20-3). The chapter index links are in blue and the font is different from the actual chapter index. To the right of each chapter index page the links are active and may be used to navigate to other chapter indexes (figure 20-4). Figure 20-3: Chapter Topics Links CHAPTER 2ERO - H e lp and' N a v ig a ti. CHAPTER. TS70 - I n t r o d u c t io n CHAPTER THREE - S uspended S t r u c t u r e s CHAPTER FOUR - S ta y e d S t r u c t u r e s CHAPTER. F IV E - V e c to r A n a ly s is CHAPTER S IX - Case S tu d ie s CHAPTER SEVEN - C o m p a ra tiv e S tu d y CHAPTER EIGHT - S ta n d a rd s CHAPTER N IN E - D e t a i l CHAPTER TEN - Summary CHAPTER ELEVEN - G lo s s a r y CHAPTER TWELVE - Q u ic k In d e x Figure 20-4: Chapter Links Clicking on any of the blue links will load the page with the topic. Hence, the user may engage in any of the two methods to navigate either linearly or directly to topics of interest. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 204 20.5 Parts of the Graphical User Interface The GUI of Catalyst is simple to use providing the user ample amount of navigation controls. JUaidgat&jfiulhkLitie. teal* ■ — ft:- . ® Attw uinvR t/, an. fo? T r t j s r & M e r * r h e H i i i-.d l'M ' * U p i - 'f t * ? 1i • . i ’ S V s a & n H e < r r p ? C '/ f w i ... w i * ' K f « H $ r r v f e a - r f " f c O r i « ? t c ' o t n i ' - W i g f * u £ to tile i < * h % • » fe v tf te n r * » w v fe k r f e :r d ^ p a r tf C •MWKHvjiw #k$-- I ;&'i Is rvj.'id f^iOc^r arm OfrtqjrK{ t M S M T ) I f t f f a u t^ t t f & T jr H T nir f l t f t 'say ;-;d < 5 - 5 t s t ibw? Pi s '«u* ... itii,e ssg k far tare* sre » a a < j* an* 1 tf fr? *■#&* & t- ta - im tB - C f lf r i f - i n t * i t t o n 'i t i * ~ B m B K l i n ' i^ d -iy C .g .C fe ?he icc\ ffavlgate within a J & m m M •rnmmmm i utton Figure 20-5: The GUI of Catalyst Three sets of panels are provided to achieve ease in navigation and the level of user control is high (figure 20-5).The three panels are discussed next. The three sets of panels used are called Top Navigator Panel (figure 20-6), the Main Navigator (figure 20-7), and the Bottom Navigator Panel (figure 20-8). The top navigator panel is used to move in between pages (which are in Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 205 essence, topics) of the currently active chapter. This panel cannot be used to navigate outside each chapter or to move between individual screens. : . iii^ . . '. . : : . i . . . . . . . . . '. . iiiiiiiiiiiii|;l^'._ ..: : ." ....jillflf lilli:' : ■ ■ ; : ■ i.: Figure 20-6: The Top Navigator Panel Figure 20-7: The Main Navigator Panel Figure 20-8: The Bottom Navigator Panel Each page is made up of several screens. The Main Navigator Panel is the most powerful panel with buttons to navigate between pages (sections), between chapters as well as to the top most level, the TOC. The categorization of data in Catalyst is analogous to the parts of a book; the Chapter is analogous to a Section while the ‘page’ is analogous to the chapters in a book. Hence, each ‘page’ in Catalyst can be made up of Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. several screens, analogous to pages in a book within a chapter (figure 20-9). The diagram below explains the same. HAP T E R , CSeetioa off a book} (Chapter An } f i (Page One) (Page Two) (Page Ehree} Figure 20-9: The Navigation Analogy in Catalyst (parts of a book) The buttons and links provided in each navigation panels are discussed next. At any time, the user has to option to exit, by pressing the escape button. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 207 20.6 Navigation Buttons: type and function One of the most important buttons that will be used most frequently is the Progressive step button (figure 20-10). This button is used to browse the tool in a linear format. The Progressive step button is used to navigate in between all pages in the forward direction. It is important to understand that the word, ‘Page’ in the GUI means topic rather than the conventional meaning. This is, since each ‘page’ has several screens (usually three to four) which are loaded while the top and bottom links may show the same page as active. Each of the screens is loaded when the progressive step button is engaged. The other two important buttons are the Help Menu and Table of Contents buttons (Figure 20-11). As the names describe these buttons may be used at any time to load the help file or access the TOC. It is important to note that the application does not create a log file to remember the level at which H e lp T a b le of M en a C o n te n ts B u tto n B u tto n Figure 20-10: Progressive Step Figure 20-11: Help and TOC buttons Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 208 the buttons (Help or TOC) were engaged and hence to return to the same section is not possible. The table of contents has to be used to return to the portion from where either of the buttons may have been engaged. Figure 20-12: The Main Navigator Panel Next Page Previous Page -i Next Chapter v Previous Chapter Figure 20-13: The Navigator Buttons The buttons available in the Main Navigator Panel (figure 20-12) are the Next Page, Next Chapter, Previous Page and Previous Chapter buttons. These buttons help the user to browse to different pages (sections) within a Chapter or to the beginning of the preceding or succeeding chapters. The next page button and the progressive step button are deactivated when the user Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 209 reaches the end of a chapter. The user may employ the next chapter or the TOC to browse further. A t any given tim e it’s possible to determ ine the current location in the application. This has been achieved by highlighting the links in the top navigation panel as well as the bottom navigation panel. The links are highlighted in blue in the active screen (figure 20-14). ■ ■ ■ a — a rfn ftu tii an m 6 halUyify-teid Htout d * t enter mre, to p o d n n % yyr’ imR-rr i\ Ip i '\ z •jji’pf s . able ssuuTry svand na-. two as -« T * Arst stim ds arp ixte.1 i n fpanufarture nrw rsrope its a (vrtixin & IL f-'& ttf tins ^inai Vrt&uct Typ-^ a: sbenda U V 8 appkaUm K K T d d e ?, IS. 57 and B 1 Hlr*nd .s aW ^ as sp trubtttiu? rosd ranyrsq fsinK;?n nember ^ r e flewfe*** or > w i * majK fo r any given overall d^np'^f-r. straws v«H afesystK 'tij; iea-a ‘ di steeirabfuc A •jaa.dU r# si?* fur p p T u id t'k tr - tt m 5 K ;r n ^ r o 'itio n g fn T n w w c p tt! « & n : « * « a f liw f n 'M tnnw ta r* ? i! i *?';& v. ;>,yf fjia n t ih ffiteOft&Vi-sf d S s n tf to ■ . * & * > l < ^ < 3 ; tn d v k k J ^ s ij^ n tiu a re m anofaiiueil ir- 4tew*ters: ^ ir«£:u^-. ■ *,> '. * var. i'L-r<t3 » *i a-' .fr.any - . ; ■ ■ ■ i.j .' V - ' . ' S : . ' , Strai S * S S ■ Figure 20-14: The current location is highlighted in blue on every page Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 210 20.7 Viewing Movies: Controls and Video All videos em bedded in the application are in M icrosoft AVI format. Hence, if the conventional W indow s Media Player is installed on the system, viewing videos should pose no problem. If codec problem s do occur the user m ust check if the ‘Cinepak’ codec by Radius is installed. The Cinepak codec can be downloaded from the W indows m edia player site, and this is usually perform ed autom atically by the player. The screens with video content appear along with controls fo r playback and other controls like forward and rewind (figure 20-15). m a -.z: anti if • o\r •! was netit ally *a*d sround jjrrtTifj a s i r ^ n uithr ■ tee; i Aw tuif* t u t* y * -;l grands -itzQ n* f t * rfiwwSar lure of w d rapt, as 8 c o n p ta ttr ,m me finst product I yoa s- sbanctstor thte appara&onttoufr * ift. 3 ? m l m StraruJ -a ab ou sea & & an itK&vKtaUlusrf u r ty 'ta r&'-S'un whtrie fic«ifc4«!iv ut ** hot a w q u r c f f la f t i f> j| a n y d > * £ ? i o w s h g t f id S fiS M m»,d Ik n* V3)l * i9 u U i? M l i iU J tt 'S ASti i\v>. o! -•U'Sfn **h j» Jfr S (nad f.axh's.M', .fe*»nqrr« t»* w » 3»tf r jtiu r».t 3sv:-r. riaMKe*' or catws f c i 2 t H f ? femat - - u o r essta a& p i h i •;tiand tr 'ftrjrtdr?.' -ap t; - atirra Jr^vtdus: **:&&% > > fr. 4 s -a. j 1 ; .j< ( tv - k l 3 6 0 twfi fflm m Figure 20-15: The screen with a video field Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 211 If scrolling text fields are present in the text box next to the video, field the scrolling controls will rem ain active fo r the user to read the text while listening to the explanations provided in the videos. The user has the option to skip the videos since the videos are paused and have to be played manually. The movie controls have m ouse-overs so that the user can understand the function o f the controls. All videos em bedded have voice-overs and the user can also use the TO C to navigate directly to chapters or screens containing these videos. The controls are rewind, play, pause, stop and forward in that order (figure 20-16). Figure 20-16: The Playback controls 20.8 The Interactive 3D Models This section is perhaps the m ost im portant to understand since the controls to view a 3D m odel are purely custom ized at the tim e o f authoring. The application relies heavily on renderers available/installed locally on the m achine. The conventional renderers available are software consisting of OpenGL, DirectX or the em bedded Shockwave 3D plug-in. Hardware acceleration is also possible in case o f system s with RAM higher than 128MB (128 m egabytes) and a 3D accelerator V G A card (graphic chipsets) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 212 with a m inim um o f 32M B m em ory onboard. Some o f the chipsets recom m ended for smooth playback are, Nvidia G eForce2 and above, Riva TN T2 and above, VoodooS and above, ATI A ll-in-W onder 8000 and above, M atrox M onster as well as Diam ond Vipers. A typical screen with 3D elem ents consists of tw o portions, the left half with the virtual 3D m odel and the right h a lf w ith an im age explaining the different com ponents o f the model (figure 20-17). M ost o f the interactive 3D m odels appear in the chapter with details, differentiating the prototypes and the custom ized applications. ■ H k . jilt * C . SW'.VC-: 5C - I'-V i p . s f . ■ ; « * 1 4 : ,r 5 - : . ’ i. - * * • ' -C vr! Figure 20-17: The Interactive 3D Model Screen Reproduced with permission of the copyright owner. Further reproduction prohibited without permission 213 The chapter that contains details also has preceding pages explaining the typology of the details and links are provided to skip directly to the 3D models. The models can be rotated, zoomed as well as orbited around with the help of customized controls. These are explained next. Each interactive m odel has a default position, based on the cam era settings where the object w as im ported (figure 20-18). To view the m odels, a com bination o f m ouse and keyboard com m ands are used. To determ ine the correct point w here m anipulation occurs, the m ouse cursor changes from an arrow to a closed hand cursor. The following controls m ay be used to view a model: • UP arrow (keyboard) - To zoom in • DOW N arrow (k e y b o a rd )-T o zoom out • R (keyboard) - T o reset the cam era position • LEFT arrow (ke yb o a rd )-T o doily camera to the left • RIGHT arrow (keyboard)-To dolly camera to the right • Left Mouse Button - Rotates the entire model about its X and Y axis • Right Mouse Button - Orbits the camera about the X axis of the model Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 214 Figure 20-18: The Interactive 3D Model 20.9 Concluding Remarks The user has the option to quit the application at any tim e by pressing the escape key on the keyboard or by clicking the quit button. A t the end o f each chapter, a link is provided to dow nload a PDF version o f that chapter (figure 20-19). This link loads a PDF docum ent which can be saved locally onto the hard drive or can be used to generate a printing protocol. The glossary page contains definitions and term inologies and this page can be accessed via the TOC. W hen the application exits, the user gets to see the references, program s used to author as well as credits and acknowledgem ents. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 215 Chapter 21: Next Level of Iterations 21.1 Introduction The final product o f the research and analysis is a tool bundled on a com pact disc for use on personal com puters. The possibility o f taking such a product to the next level involves m any areas that have not yet been tapped. This chapter looks at these dom ains, from the author’s point of view as a researcher, a student o f architecture and a developer. 21.2 The First Domain: Systems to be studied The process o f m aking this tool has rendered another im portant byproduct. A generic tem plate, in *.dir form at which allows any data to be entered and finally create executable files fo r distribution. For this research, the topics studied in detail are cable stayed and cable suspended system s and structures. Although, as a part of the research, the author has tried to cover as m any exam ples o f bridges and architectural installations, there can be a clear cut distinction between them . The physics involved in each typology can be dissim ilar and thus two new genres can be dealt with in detail, separately. This would be a m ore com prehensive study with em phasis on how the system s w ork based on the scale. For instance bridges that have very large spans and hence, the floor deck behaves differently when other Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 216 systems of structures like trusses and girders are added. For architectural applications, the em phasis is on using tie rods rather than wire-ropes which is most suitable for bridges. The behavior of tie-rods is different, since even cross-section areas are calculated with different param eters, unlike ropes which have 60% m etallic cross section areas. This is one such area of research. O ther dom ains that m ay be added include studying the behavior of the different elem ents o f these system s to dynam ic loads. Failure of bridges like the T aco m a Narrows Bridge’ due to dynam ic forces can be added. Additionally, m ore num erical exam ples, based on num eric vector analysis can be added. In case of a cable stayed system , the deck is always in com pression and this quality is im portant since it is a requirem ent even at the tim e of construction. An exam ple o f a typical system construction and how the deck is kept in com pression can be dem onstrated. Detailed analysis o f each system using com puters can be added. An im portant quality o f the suspension system is that the suspender cables behave differently under different kinds o f loads. The Catenary shape can vary from sim ple funicular to parabolic curves Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 217 depending on loading conditions. Such behavior can be studied in detail for different load conditions with com parisons m ade to real life exam ples with em phasis on synergy and style o f construction. The generic tem plate described earlier clearly provides a good backdrop to study other system s like trusses, beam s and fram es, com plex eccentric braced system s as w ell as tube system s and assem ble the inform ation in the tem plate. The basis o f the research at this level would be to collect data and maxim um em phasis can be given to this criterion since the tem plate would accept the data. In the research carried out at this level, em phasis w as laid on the system s, but at the sam e tim e, the m ethod to dissem inate the inform ation w as also a crucial issue. From here on the m ethod to dissem inate the data can be a m inor issue and the researcher can give full em phasis to the background research. This can be im plem ented using any system o f construction and does not have to apply to the dom ain dealt in this research. 21.3 The S e c o n d Domain: E m b e d d in g New A p p lic a tio n s Further iterations can also involve links to m anufacturer sites after licensing and the user can have access to crucial data before actually designing and Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 218 proposing a system . This system works, since the authoring application allows encryption and hence, security issues can be minimized. Additionally, external stand alone program s for design, analysis as well as conceptual study can be linked into the program and volum es o f data can be stream ed over secure networks. For architecture students it is im perative to have good design skills and at the sam e tim e, possess analytical skills so that a design proposal is com plete in all respects. T o assist this, the tool can have analytical algorithm s em bedded to perform case analysis based on given quantities. A good exam ple would be calculation o f sag fo r a suspended system based on different load conditions and finally, com puting the head room for a case where the supports are at different levels. For instance, when a span is entered, the program should be able to com pute suspender tension, the kind of sag and even devise a conceptual figure (which m ay or m ay not be to scale). This certainly requires em bedding Java based applets into the program, but the research can be restricted to sim ple tw o dim ensional figures or com plex Java 3D applets fo r m ore accurate sam ples. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 219 Additionally, sim ple drawing applets as a part o f graphic vector analysis can be im plem ented. This m eans that a user would enter m agnitudes o f a joint load for a stayed system o r in another instance the angle o f the vector which is the tangent to the suspension cable with the m agnitude o f the vertical load. The program w ould then construct a scaled vector triangle or a force polygon based on the entry. A lthough the scale o f the triangle can be restricted to a given num ber, the program can have an option fo r the user to print this vector triangle o r force polygon and use it fo r reference. In addition to this, the com pression o f decks in case o f stayed system s can be dem onstrated graphically to scale. 21.4 The Third Domain: Technical Additions (Multimedia) The next dom ain to be explored is the m ultim edia aspect of the tool. Once the tool grows in quantity, it would be desirable to introduce a m em ory module. In sim ple term s, the program would have a system o f m aintaining bookm arks based on the level at which the user exits the application. This can be done by writing a lingo script to rem em ber values in a log file that would be saved locally on the hard drive w here the disc is accessed. Another addition would be the possibility o f introducing user capability to place actual bookm arks at his/her will on pages and then these values being Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 220 reflected in the table of contents or as a separate page with topic headings. This would help in easy navigation to topics o f interest at any level. In addition to the system o f bookm arks a search engine can also be em bedded fo r finding term inologies or quantities based on a system o f keywords. The tool would then grow to a level of becom ing an intranet. The next major change would be the m edium o f delivery. Consolidation to run over networks or bundling the sam e on to a DVD could be the next option. Scratch pads on each page can also be the next line of additions to the tool. The user w ould be able to copy text selectively and paste it onto a scratch pad. The user then has the option to save this text onto a sim ple notepad docum ent within the program. Real tim e problem solving m odules could be another set o f additions lined up from the m ultim edia author’s point o f view. The application would have em bedded algorithm s to sort the kind o f data entered and then give options to the user to choose the kind of output, num erical, graphic or both. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 221 The other possibility o f adding Al (Artificial Intelligence) to assist this process is another very am bitious avenue. A lthough, today com plex program m odules are available to carry out com plex operations; these are being fast replaced by A l w hich carries out the operations by ‘thinking’ rather than generating error logs. A very good exam ple is th a t o f A l implemented in dark light factories w hich involve m anufacturing in the m otor industry. In dark light factories hum an intervention is com pletely eradicated to assist the m anufacturing process. Entire m anufacturing units are run by such entities and these possess the capability o f trouble shooting problems. Al can be used to perform com plex calculations, com puting real-tim e anomalies based on com plex loading conditions as well as generating life like calculations of structural behavior from 3D m odels with actual loading conditions in the virtual realm. 21.5 Conclusion Creating such a powerful tool can be segregated into different levels o f expertise to define contributing research topics and hence, im plem enting the sam e would be a task that would involve not only the expertise o f architects, but also that o f civil and structural engineers as well as com puter science engineers. The outcom e of this would be a very large learning database with powerful interactive capabilities, unlike this research which is more o f a Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 222 com puter aided design tha t contributes to the learning process. Such a data base m entioned afore would be accessible from any part o f the world over a network or on a m edium like a DVD fo r persona! usage. The avenues to experim ent and carry out such a large task rem ain open and can be im plem ented over a period o f tim e to m ake the process o f learning even m ore interesting and assisting the instructor while sharing his responsibilities equally. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 223 Glossary A butm ent - the outerm ost end supports on a bridge, which carry the load from the deck Anchorage - a secure fixing, usually m ade o f reinforced concrete to which the cables are fastened A queduct - a bridge or channel fo r conveying water, usually over long distances Arch Bridge - a curved structure that converts the downward force o f its own weight, and o f any w eight pressing dow n on top o f it, into an outward force along its sides and base Arch Dam - a dam with an arched shape that resists the force o f w ater pressure; requires less m aterial than a gravity dam fo r the sam e distance Architect - a person who designs all kinds o f structures; m ust also have the ability to conceptualize and com m unicate ideas effectively - both in w ords and on paper - to clients, engineers, governm ent officials, and construction crews Beam - a rigid, usually horizontal, structural elem ent Beam Bridge - a sim ple type of bridge, com posed of horizontal beam s supported by vertical posts Bedrock - the solid rock layer beneath sand or silt Brace - a structural support; to strengthen and stiffen a structure to resist loads Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 224 Brittle - characteristic of a m aterial that fails w ithout warning; brittle m aterials do not stretch or shorten before failing Buckle - to bend under com pression Buttress - a support that transm its a force from a roof or wall to another supporting structure Buttress Dam - a gravity dam reinforced by structural supports Cable - a structural elem ent form ed from steel wire bound in strands; the suspending elem ent in a bridge; the supporting elem ent in som e dome roofs Cable-Stayed Bridge - a bridge in which the roadway deck is suspended from cables anchored to one or m ore tow ers Caisson - a watertight, dry cham ber in which people can w ork underwater Cantilever - a projecting structure supported only at one end, like a shelf bracket or a diving board Cast Iron - a brittle alloy with high carbon content; iron that has been m elted, then poured into a form and cooled; can be m ade into any shape desired Civil Engineer - an engineer w ho plans, designs, and supervises the construction o f facilities essential to modern life Cem ent - a binding material, or glue, that helps concrete harden Coffer - a sunken pane! in a ceiling Cofferdam - a tem porary dam built to divert a river around a construction site so the dam can be built on dry ground Column - a vertical, structural elem ent, strong in com pression Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 225 C om pressed-A ir Cham ber - the space at the bottom o f a caisson into which air is introduced under pressure to exclude w ater so that excavation can take place Com pression - a pressing force that squeezes a m aterial together Concrete - a m ixture of w ater, sand, sm all stones, and a gray pow der called cem ent Construction M anager - a person w ho coordinates the entire construction process - from initial planning and foundation w ork through the structure's com pletion C ontinuous Span Beam Bridge - sim ple bridge m ade by linking one beam bridge to another; som e o f the longest bridges in the world are continuous span beam bridges Core - central region of a skyscraper; usually houses elevator and stairwell C ut and C over - a m ethod o f tunnel construction that involves digging a trench, building a tunnel, and then covering it with fill Deck - supported roadway on a bridge Deform - to change shape Dome - a curved roof enclosing a circular space; a three-dim ensional arch Electrical Engineer - an engineer concerned with electrical devices and system s and with the use o f electrical energy Em bankm ent Dam - a dam com posed of a mound of earth and rock; the sim plest type o f gravity dam Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 226 Engineering - a profession in which a knowledge of math and natural science is applied to develop ways to utilize the materials and forces of nature for the benefit of all human beings Environm ental Engineer - an engineer w ho designs and operates system s to provide safe drinking w ater and to prevent and control pollution in water, in the air, and on the land Force - any action that tends to m aintain or alter the position o f a structure G eodesic Dom e - a dom e com posed o f short, straight pieces joined to form triangles; invented by Buckm inster Fuller Gravity Dam - a dam constructed so that its great w eight resists the force of w ater pressure iron - a chem ical elem ent (Fe); one o f the cheapest and m ost used m etals Joint - a device connecting tw o or m ore adjacent parts o f a structure; a roller joint allows adjacent parts to move controllably past one another; a rigid joint prevents adjacent parts from m oving or rotating past one another Load - w eight distribution throughout a structure; loads caused by wind, earthquakes, and gravity, fo r exam ple, affect how w eight is distributed throughout a structure Masonry - a building material such as stone, clay, brick, or concrete Mechanical Engineer - an engineer who applies the principles of mechanics and energy to the design of machines and devices Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 227 M onolithic Dome - a dom e com posed o f a series o f arches, joined together with a series o f horizontal rings called parallels Perim eter - the distance around the outside of a shape Pier - a vertical supporting structure, such as a pillar Pendentive - a triangular shape that adapts the circular ring o f a dom e to fit onto a flat supporting wall Pile - a long, round pole of wood, concrete, or steel driven into the soil by pile drivers Pile Driver - a noisy m achine that repeatedly drops a heavy w eight on top of a pile until the pile reaches solid soil or rock or cannot be pushed down any farther Plastic - a synthetic m aterial m ade from long chains o f m olecules; has the capability o f being molded or shaped, usually by the application o f heat and pressure Pressure - a force applied o r distributed over an area Reinforced Concrete - concrete with steel bars o r m esh em bedded in it for increased strength in tension; in pre-tensioned concrete, the em bedded steel bars or cables are stretched into tension before the concrete hardens; in post-tensioned concrete, the em bedded steel bars o r cables are stretched into tension after the concrete hardens Richter Scale - used to m easure the m agnitude o f an earthquake; introduced in 1935 by the seism ologists Beno Gutenberg and C harles Francis Richter Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 228 Shear - a force that causes parts of a materia! to slide past one another in opposite directions Shear-W alls - solid concrete walls that resist shear forces; often used in buildings constructed in earthquake zones Silt - sedim ent particles ranging from 0.004 to 0.06 mm (0.00016 to 0.0024 inch) in diam eter Span - the distance a bridge extends between tw o supports; (v.) to traverse a specific distance Spillway - an overflow channel that allow s dam operators to release lake w ater w hen it gets high enough to threaten the safety of a dam Spire - an architectural or decorative feature o f a skyscraper; the Council on Tall Buildings and Urban Habitat includes spires but not antennae when calculating the official height of a skyscraper Stable - (adj.) ability to resist collapse and deform ation; stability (n.) characteristic o f a structure that is able to carry a realistic load w ithout collapsing or deform ing significantly Steel - an alloy o f iron and carbon that is hard, strong, and m alleable Stiff - (adj.) ability to resist deform ation; stiffness (n.) the m easure o f a structure's capacity to resist deform ation Story - flo o r o f a skyscraper Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 229 Structural Engineer - an engineer w ho investigates the behavior and design o f all kinds of structures, including dam s, dom es, tunnels, bridges, and skyscrapers, to make sure they are safe and sound fo r hum an use Suspension Bridge - a bridge in which the roadw ay deck is suspended from cables that pass over two towers; the cables are anchored in housings at either end o f the bridge Tensegrity - an array o f tension cables and com pression rods that supports a structure; invented by Buckm inster Fuller student Kenneth Snellson Tension - a stretching force that pulls on a m aterial Tension Ring - a support ring that resists the outw ard force pushing against the lower sides o f a dom e Torsion - an action that twists a material Tow er - the vertical structure in a suspension bridge or cable-stayed bridge from which cables are hung; also used loosely as a synonym fo r the term skyscraper Truss - a rigid fram e com posed o f short, straight pieces joined to form a series of triangles or other stable shapes Unstable - characteristic o f a structure that collapses or deform s under a realistic load W rought Iron - an iron alloy that is less brittle than cast iron Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 230 Bibliography (Books) Am erican Society o f Civil Engineers 1997, Standard Guidelines for the Structural Applications of Steel Cables for Buildings, Cat. No.97-16275, ASCE, New York. Devezic, Vladan and Harrer, Andreas 2002 (Department of Inform ation Systems, School of Business Adm inistration, University of Belgrade, Belgrade Yugoslavia), ‘Architectural patterns in pedagogical agents’, in Intelligent Tutoring Systems: Proceedings of ITS 2002: 6th International Conference, Biarritz, France and San Sebastian, Spain, June 2-7 2002, LNCS2363, (eds.) Stefano A Cerri, G uy Gouarderes and Fabio Paraguagu, Springer Publications, Berlin, pp. 81-84. Fooks, R. 1986, (Faculty o f Environm ental Design and Construction, Royal M elbourne Institute O f Technology, M elbourne, Australia), ‘An integrated approach to the teaching o f light w eight structures in a School of A rchitecture’ in The First Conference on Light Weight Structures in Architecture, Sydney Australia, 24th July to 29th July 1986, vol. 2, Unisearch Limited, The University o f South W ales, Kensington, Australia, pp. 865 - 869. Gensert, R. M., (eds.) 1966, (R .M .G ensert and Associates, PA), Cable Construction in Contem porary Architecture, a hand book fo r Bethlehem Steel Corp., Bethlehem Steel. Harris, Jam es B. & Li, Kevin Pui-K, (eds.) 1996, Masted Structures in Architecture (Butterworth Architecture New Technology Series), Architectural Press, Butterworth Architecture New Technologies, Oxford; Boston. Hefferman, Neil T. and Koedinger, Kenneth R. 2002, ‘A n intelligent tutoring system incorporating a m odel o f an experienced hum an tutor’, in Intelligent Tutoring Systems: Proceedings of ITS 2002: 6® international Conference, Biarritz, France and San Sebastian, Spain, June 2-7 2002, LNCS2363, (eds.) Stefano A Cerri, Guy G ouarderes and Fabio Paraguagu Springer Publications, Berlin, pp. 596-600. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 231 Howard, Seym our Jr., (eds.) 1966, (Professor o f Architecture, Pratt Institute, NY.), Suspended Structures Concepts, A handbook for United States Steel Corporation, United States Steel. M avrikis, M anolis (Departm ent o f M athem atics and Statistics) and Lee, John 2002 (Departm ent of Inform atics; cognitive science); University o f Edinburgh, EH9 3JZ, Scotland, UK), ‘Tow ards m ore affective Tutoring System s’, in Intelligent Tutoring Systems: Proceedings of ITS 2002: £r International Conference, Biarritz, France and San Sebastian, Spain, June 2-7 2002, LNCS2363, eds. Stefano A Cerri, G uy Gouarderes and Fabio Paraguagu, Springer Publications, Berlin, pp. 1003. Schierle, G G (2003) Structures, Wiley and Sons Schierle, G G (1968) Lightweight Tension Structures, UC Berkeley Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 232 Bibliography (Internet) Anthony Hunt A ssociates 2002, Anthony Hunt Associates: Inmos Ltd 2002, inmos Limited, FAB II, Newport, Gwent [online] Available: http://w ww. anthonyhuntassociates. co. uk/inm os. htm (Accessed 09 August 2002). Architecture W eek 2001, ‘Design w ith G lass A w ards’, in Architecture Week (Page D1.1. 30 M ay 2001) [online] Available: http://www.architectureweek.com/2001/0530/design_1-2.html (Accessed: 2 Novem ber 2002). Bauen Mil Stahl 2001, M essehalie 26 in Hanover, in Bauen Mit Stahl [online] Available: http.7/www.bauen-m it-stahl,de/galerie/m esse/m essehalle_hannover.htm (Accessed 2 Novem ber 2002). Brandt R 1999, ‘Bridging the Bay: Bridging the Cam pus; G olden G ate’, in Bridging the Bay Online Exhibit: UC Berkeley Library [online] Available: http://w ww .lib.berkeley.edu/Exhibits/Bridge/gate_1 .html (Accessed 2 November 2002). Dupont Benedictus 2001, ‘2001 Dupont Benedictus Aw ards for Innovation in Architectural Lam inated Glass: W inners and Honorable M entions’, in Dupont Benedictus Awards [online] Available: http://w w w .dupontbenedictus.eom /2001w inners.htm #students (Accessed 2 Novem ber 2002). 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Janberg, Nicolas 2000, ‘H anover Trade Fair, Hall 2 6 ’ in Structurae: International Database and Gallery of Structures [online] Available: http://w w w .structurae.de/en/structures/data/str00919.php (Accessed 2 Novem ber 2002). Janberg, Nicolas 2000, ‘Hanover Trade Fair, Hall 9’ in Structurae: International Database and Gallery of Structures [online] Available: http://w w w .structurae.de/en/structures/data/str00916.php (Accessed 2 Novem ber 2002). Janberg, Nicolas 2000, ‘Inmos M icro electric Plant, New Port, G w ent’, in ‘Structurae: International Database and Gallery of Structures’ [online] Available: http://w w w .structurae.de/en/structures/data/str00833.php (Accessed 15 A ugust 2002). Reproduced with permission of the copyright owner. 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Locke, D. 2002, ‘Cable Stayed Bridges’ in Braniacan Bridges [online] March 2002, Brantacan UK, Available: http://w ww .brantacan.co.uk/cable_stayed.htm (Accessed 12 O ctober 2002) Locke, D. 2002, ‘Suspension Bridges’ in Brantacan Bridges [online] March 2002, Brantacan UK, Available: http://www.brantacan.co.uk/suspension.htm (Accessed 12 O ctober 2002) Matthews, Kevin and A rtifice, Inc. 2001, ‘Inm os Factory', in The Great Buildings Collection (w w w .greatbuildingsonline.com ) [online] Available: http://w w w .greatbuildings.com /buildings/IN M O S_Factory.htm l (Accessed 12 May 2002). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 235 National Athletics Stadium Canberra, A ustralia 1998, Key Center of Design Computing and Cognition: The University of Sydney, Sydney, Australia. [online] Available: http://www.arch.su.edu.au/kcdc/caut/html/NAS/front.htm (Accessed 20 September 2002). 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TO YO TA STADIUM: TO YO TA STADIUM Opened in July, 2001’ in Welcome to Toyota City [online] Available: http://www.city.toyota.aichi.jP/english/report/football_stadium .htm f#foot1 (Accessed 30 O ctober 2002). Von G erkan, Marg und Partner 2002, T ra d e Fair Hanover, Hall 8/9’, in Von Gerkan, Marg und Partner, Architects [online] Available:http://w w w .gm p-architekten.de/2projects/expo8-9/expo8-9.htm (Accessed 2 Novem ber 2002). W est, Brad 1996, ‘Antialiasing and Transparency: A n online tutorial’ in LunaLoca: Online tutorials [online] Available: http://w w w .lunaloca.com /tutorials/antialiasing/ (Accessed: 9 May 2003). W iley, David (Assistant Professor, Instructional Technology, Utah State University) 2002, Theory to practice: Using dom ain theory to m odel learner expertise’ in "Wiley Writings” [online] Available: http://w iley.ed.usu.edu/docs/m usic_dom ain_theory.pdf (Accessed October 7, 2002). YUBuild G roup 2001, ‘AIR C R A FT HANG AR OF TH E Y U G O SLAV AIR LIN ES - Belgrade’, in YUbuild, Yugoslavia Construction Expertise [online] Available: http://w w w .yu-build.eom /m ain/h/091/091.htm l (Accessed 2 Novem ber 2002). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

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Asset Metadata

Creator Shenoy, Gautam Ramchandra (author)

Core Title Catalyst: A computer-aided teaching tool for stayed and suspended systems

School School of Architecture

Degree Master of Building Science / Master in Biomedical Sciences

Degree Program Building Science

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag Architecture,education, technology of,engineering, civil,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Advisor Schierle, G. Goetz (committee chair), Guh, Jeff (committee member), Kale, Nitin (committee member), Kensek, Karen (committee member), Noble, Douglas (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c16-309535

Unique identifier UC11336816

Identifier 1417941.pdf (filename),usctheses-c16-309535 (legacy record id)

Legacy Identifier 1417941.pdf

Dmrecord 309535

Document Type Thesis

Rights Shenoy, Gautam Ramchandra

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA