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Terrace housing: A conscious solution

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Terrace housing: A conscious solution

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Content INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. 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 bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI 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. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6’ x 9” black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. ProQuest Information and Learning 300 North Zeeb Road. Ann Arbor, Ml 48106-1346 USA 800-521-0600 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TERRACE HOUSING: A CONSCIOUS SOLUTION Copyright 2001 by Maili Sekiguchi A Thesis Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE (BUILDING SCIENCE) August 2001 Maili Sekiguchi Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 1409604 Copyright 2001 by Sekiguchi, Maili Y. All rights reserved. _ _ ____ _ _ (g ) UMI UMI Microform 1409604 Copyright 2002 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 T H E G R A D U A T E SCHO O L. U N IV E R S IT Y R A R K L O S A N G E L E S . C A L IF O R N IA S O 0O 7 This thesis, written by tiM kt ____________ under the direction of hd£.— Thesis Committee, and approved by a ll its members, has been pre sented to and accepted by the Dean of The Graduate School, in partial fulfillm ent of the requirements for the degree of L. . . . eu. i kPi i0 4 ...^a.£Ur^. j Date....£...\lS^„h*A\. / Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Acknowledgments There are a number of people to whom I would like to express my most sincere gratification. Thank you... My Family, you have been my source of strength, inspiration and unconditional support throughout every step of my life. Prof. Goetz Schierle, for your inspiration, your constant encouragement to strive for more, your enthusiasm and the unlimited amount of time, advice and knowledge you allocated me in the completion of this thesis, especially for the extra encouragement when I needed them the most. Prof. Marc Schiler for the many opportunities and challenges that you gave me throughout my studies in MBS, thank you very much for your valuable time, knowledge, patience and embracing us as part of your family. Prof. Ralph Knowles for your amazing approach in your teaching. Through it I have found a new appreciation in the usage of the sun through every day activities. Thank you for your time and knowledge for the completion of my thesis. My classmates and friends in the School of Architecture, for making these years an amazing experience. I would like to especially thank Nazneen, Candace, Nazanin and Binny. Thank your for the time, critic, care and support you gave me throughout the completion of my thesis. ii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table of Contents AKNOWLEDGMENTS ii ABSTRACT xiii PREFACE xiv CHAPATER 1 Introduction - Why Sloping Site? 1 1.2 Current High Density Solutions 2 1.3 Shortage of Land on Rat Sites 4 1.4 Current Solutions of Sloping Sites 6 1.5 Hillside Development 9 1.6 Advantages 10 CHAPATER 2 13 Introduction - Advantages of Sloping Sites 13 2.1 Bad Design Examples 14 2.2 Necessary Elements 17 2.3 Terrace Housing 18 2.4 Terrace Housing in Developing Countries 20 2.4.1 Background 20 2.4.2 Development 22 2.5 Future Possibilities 23 CHAPATER 3 25 Existing Similar Structures 25 3.2 Case Studies 29 iii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3.2.1 Hemnosa Beach, CA Terrace Housing 29 3.2.2 Rokko Housing in Kobe Japan 32 3.2.3 Stepped Housing, Zurich Swizeriand 34 3.2.4 Environmental Residence 36 CHAPATER4 Housing Needs in Developing Countries 37 4.1 Background 37 4.2 Housing Characteristics in Mexico 38 4.3 Current Practice 40 4.4 Developing Process 41 4.5 Row Housing 43 4.6 Materials 43 4.6.1 Concrete Block 44 4.6.2 Brick 44 4.6.3 Wood 44 4.6.4 Alternate Materials 45 4.7 Technology 45 4.7.1 Pre-fabrication 46 4.8 The Future of Housing 47 CHAPATER 5 Soil Behavior and Land Treatment 46 5.1 Introduction 48 5.2 Slope Stability Analysis 49 5.3 Major Problems for Landslide 50 5.4 Landslide Prevention and Control 52 iv Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 5.4.1 Bio-technical Stabilization 52 5.4.2 Stabilization with Tires 54 5.5 Disasters 57 5.6 Cut and Fill 60 CHAPATER 6 Mexico- History and Background 62 6.1 Mexico 63 6.1.1 Location 63 6.1.2 Demographics 63 6.1.3 Education 65 Literacy 65 Basic Education 65 Education Level 66 6.1.4 Economy 67 6.1.5 Housing 68 6.2 Tijuana Baja California 69 6.2.1 Location and Background 69 6.2.2 Population 70 6.2.3 Local Economy 71 6.2.4 Border City 71 CHAPATER 7 Site Analysis 74 7.1 Site Description 74 7.2 Housing Classification 78 7.3 Site Location 79 v Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 7.4 Specifics 82 7.4.1 Figure Ground 82 7.4.2 Zoning 84 7.4.3 Access 85 7.5 The Site 86 CHAPATER 8 8.1 Principal Mission 88 8.2 Current Practices 89 8.3 Matrix 91 CHAPATER 9 9.1 Structures- Introduction 94 9.2 Foundation 95 9.2.1 Methods to adapt buildings to the site & not the site to the building 95 9.2.2 Sample Study 96 9.2.3 Beam Wall 96 9.3 Construction Materials 97 9.3.1 Wood 97 9.3.2 Advantages of Wood 98 9.3.3 Shear panel construction 98 9.4 Calculations 100 9.5 Case Study A 101 9.5.1 Section 104 9.5.2 Units 105 9.6 Detail 107 vi Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPATER10 10.1 Environmental Control- Introduction 109 10.2 Advantage of Slope Sites 110 10.3 Definition of Solar Envelope 112 10.4 Solar Envelope Parameters 114 10.4.2 Hillside 116 10.5 Case Study 118 10.6 Environmental Control 120 10.7 Internal Shadow Cast 122 10.7.2 Solar 2 123 10.8 Importance of Thermal Mass 125 10.9 Importance of Insulation Addition 126 CHAPATER 11 11.1 Conclusion 128 11.2 Advantage of Slope Sites 128 11.2.1 Matrix 129 11.2.2 Terrace Housing 129 11.2.3 Structural Elements 130 10.4.2 Hillside 116 11.3 Solar Envelope 130 11.3.1 Orientation 131 11.3.2 Determination of Fences 131 11.3.3 Two Units Side by Side per Structure 132 11.3.4 Shading devices on the Windows 133 11.4 Environmental Control 133 v ii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. BIBLIOGRAPHY 135 WEB SITES 136 v iii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table and Figures Figure 1-1 Typical Multistory, Sao Paolo Brazil 2 Figure 1-2 Private vs. Public Spaces 3 Figure 1-3 Size vs. Crime Rate 4 Figure 1-4 Usage of Land in Sao Paolo from 1933-88 5 Figure 1-5 Cut and Fill Practice in Tijuana Mexico 6 Figure 1 -6 Cut and Fill Process and Outcome 7 Figure 1-7 Landslide after Earthquake, Las Colinas El Salvador 8 Figure 2-1 Steep fumes scrapping slopes 14 Figure 2-2 Manipulation of Site with Oversize Retail 14 Figure 2-3 Flat Site Houses Manipulated terrace 14 Figure 2-4 Traditional Hillside Housing 16 Figure 2-5 Typical Existing Hillside Housing with Terrace 22 Figure 3-1 Italian Hillside Housing Section 25 Figure 3-2 Anticoli Corrado, Italy 26 Figure 3-3 Wolf House, Catalina California 26 Figure 3-4 Rational for respecting the ground for cross ventilation 28 Figure 3-5 Hermosa Beach Axon 30 Figure 3-6 Hermosa Beach, front fagade 30 Figure 3-7 Hermosa Beach, balcony and planters 31 Figure 3-8 Hermosa Beach, cross-section 32 Figure 3-9 Rokko House, axon 32 Figure 3-10 Rokko House, aerial view 33 Figure 3-11 Zurich Housing, cross section and site plan 34 Figure 3-12 Zurich Housing, fagade 35 Figure 3-13 Malibu House, fagade 36 ix Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 4-1 Self constructed community on a slope, Tijuana 38 Figure 4-2 Characteristics of a typical fagade, Tijuana 39 Figure 4-3 Tires as a main feature, Tijuana 40 Figure 4-4 Tendedero”, Tijuana 42 Figure 4-5 Combination of Tires and “ Tendederos" 43 Figure 5-1 Pre-failure stages diagram associated with landslides 49 Figure 5-2 Shear strength of Soil along failure surface 50 Figure 5-3 Bio-Technical ground cover 51 Figure 5-4 with the passage of time 51 Figure 5-5 Reinforced grass process 53 Figure 5-6 fully grown after some time 53 Figure 5-7 Retaining wall composed of tires 54 Figure 5-8 Tires used as planter and decorative elements, Tijuana 55 Figure 5-9 Tires used as the main circulation through a street, Tijuana 56 Figure 5-10 Damage at foothill of a slope, Hong Kong 57 Figure 5-11 Landslide damage 57 Figure 5-12 Luxurious Development on top of the hill after Earthquake 58 Figure 5-13 Buried houses after Earthquake, El Salvador 59 Figure 5-14 Types of Landslides 61 Figure 6-1 Map of Mexico 63 Table 6-1 Population Division According to Age Group 64 Figure 6-2 Population Distribution 1970-2000 64 Figure 6-3 Education Abandonment among 6-29 age group 66 Figure 6-4 Education level over 15 years of age 67 Figure 6-5 Wealth distribution among the population 68 Table 6-3 Break down of economical forces in Tijuana 71 Figure 6-6 Geographical composition according to Income 72 x Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 7-1 Site Plan of Tijuana, from west to east 74 Figure 7-2 Growth Pattern between 1889-1984 75 Figure 7-3 Socioeconomic division by area 75 Figure 7-4 Land Use analysis 76 Figure 7-5 Residential Housing quality according to the 1990 Census 77 Figure 7-6 Slopes, Faults and Hazardous Terrain 80 Figure 7-7 Geological Faults dose to the Los Laureles site in the US and Tijuana 81 Figure 7-8 Vegetation in Los Laureles 81 Figure 7-9 Solid and void diagram of Los Laureles 82 Figure 7-10 View ot the Canyon, Los Laureles 83 Figure 7-11 Decay and Erosion Caused by unplanned settlement 83 Figure 7-12 Los Laureles Zonning 84 Figure 7-13 Transportation ad Access, Los Laureles 85 Figure 7-14 Los Laureles Canyon 86 Figure 7-15 Los Laureles Canyon 87 Figure 8-1 Ground access to every unit 91 Figure 8-2 Continuous Structural flow 92 Table 8-1 Module Dimensions in relation to the slope 92 Figure 9-1 Hard Soil, no water absorbency, Tijuana 95 Figure 9-2 Beam Wall with even cantilever 97 Figure 9-3 Site Plan and Site Section 102 Figure 9-4 Cross Section 103 Figure 9-5 Side Elevation with unit plan 104 Figure 9-6 Typical Floor Plan 105 Figure 9-7 Structural Diagram of two consecutive units 106 Figure 9-8 Typical wall detail 107 Figure 9-9 Wall detail with continuous plywood to transfer shear 108 xi Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 10-1 Shadow cast in a north-south orientation slope 111 Table 10-1 Mean Temperature 113 Figure 10-2 Sun Path during the three seasons of the year 114 Figure 10-3 Site plan mass model 116 Figure 10-4 Site plan case study A 117 Figure 10-5 Winter, Composite, Summer envelope 118 Figure 10-6 Composite envelope determines the total height 118 Figure 10-7 Overall View from the front 119 Figure 10-8 East Elevation with the pergola outline 120 Figure 10-9 Canvas or “ toldo” as shading device 120 Figure 10-10 Poetry in Barragan’s window 122 Figure 10-11 Manual Shading devices, change with seasons of the year 125 Table 10-2 R Value for common materials 125 Table 11-1 Typical dimensions 129 Table 11-2 Typical Heights 132 xii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Abstract TERRACE HOUSING The only available land in many urban areas is on surrounding hillsides, where cut-and-fill grading is the usual answer; a technology that causes building failure in earthquakes due to uneven settlement and even landslides. Several studies following the Northridge Earthquake of 1994 demonstrated the problem of uneven settlement failure, while the recent El Salvador Earthquake caused devastating landslides due to unsafe hillside grading conditions. The objective of the study presented in this thesis was to adapt the building to the site instead of adapting the site to the building. This minimizes the grading and retaining walls for a more sustainable environment. In addition the design embraces the natural elements working in harmony with rather than against nature for a more sustainable approach. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Preface Population growth in many urban areas has largely exhausted flat land for building sites. This problem is aggravated in major urban centers of developing countries, such as Mexico City or Sao Paolo, with continuing population explosions. The rapid growth has pushed boundaries of cities outwards, while overpopulating the city centers, degrading living conditions and populating hillsides adjacent to the metropolis areas. Sloping sites are heavily populated in steep, unstable, and irregular areas endangering residents’ lives without technological support for construction of safe dwellings. This fact is emphasized drastically when figures show a grim picture for the future. It is believed that by the year 2025, 80% of the world’s population will reside in developing countries, out of which 60% are extremely vulnerable to natural disasters, such as earthquakes, floods, and severe storms. 90% of the natural disasters and 95% of the total disaster-related deaths worldwide occur in developing countries. (Fazal Moin, 2001) That is why it is imperative to take action to improve the living conditions in these urban centers. Nature is very precious, especially connection with the built environment. When we stop to think for a minute, it is amazing to realize how precious and fragile this relationship is. It is very sad to think how far and how fast we, the human species, have gone to impose our will and destroy everything in our way. It is our duty to preserve and protect the environment, and to integrate the built environment to nature the best way we know. Thanks to our thirst of ’ ’progress” and development without a thought, the only available land in many urban areas is on surrounding hillsides, where cut- and-fill grading is the usual answer; a technology that causes building failure in earthquakes due to uneven settlement and even landslides. Several studies following the Northridge Earthquake of 1994 demonstrated the problem of uneven settlement failure, while the recent El Salvador Earthquake, at the beginning of 2001, caused devastating landslides due to unsafe hillside grading conditions. The main objective of this thesis is to adapt the building to the site instead of adapting the site to the building, to minimize grading xiv Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. and retaining walls for a more sustainable environment, designed in harmony with rather than against nature. The study will include the analysis of good construction practices on sloping sites for better living conditions, optimum performance during earthquakes, and the usage of the natural resources to maximize solar access and the environmental control within the units. To this end, a terrace housing technique is proposed which is a good solution to hillside housing needs. Properly designed and constructed, terrace housing not only provides safer earthquake performance than conventional cut-and-fill developments but also provides valuable open space by means of terraces. Terrace housing minimizes site grading which is environmentally destructive and a potential hazard in earthquakes due to differential settlement of differential fill depth. It will also avoid soil erosion and reduce the high cost of excessive grading and retaining walls. Terraces also provide space for outdoor living to replace covered ground, ensuring full privacy. This allows higher density for lower land cost per unit, combining the amenities of detached residences with the cost-effectiveness of multifamily dwellings. Primarily there are two means to achieve grading reduction: A structural framing system to replace retaining walls by bearing walls that frees the building form strip foundations, combining lateral and gravity resistance capacity. A matrix of diagrams provides guidelines to correlate a structural grid with available site slopes to provide a clear load path for gravity and lateral load without the need for grading and retaining walls. The objective of this study is to provide housing at reasonable cost, adapting time-proven wood framing technology for earthquake resistant hillside housing. In developing countries due to the cheap labor costs, traditions, and availability the most commonly used materials are concrete block and brick. History has proven that these materials have endangered lives due to poor performance when not carefully built. Wood on the other hand is not widely used XV Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. all over the world, however it is a renewable source, which could vitalize the timber industry and encourage reforestation, which will help the local environment. The great advantages that wood could provide in earthquake regions would be to reduce major fatalities that have resulted in tragedies such as Turkey in 1999, Mexico City in 1985, and recently El Salvador and India in 2001. It is hoped this technology lends itself to low cost self-help production. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Chapter 1 Introduction - Why Sloping Site? The accelerated rate in which cities have been growing in the past decades has exhausted flat land for building sites. This situation has created chaos within the cities. Many cities have grown irregularly without much control, creating various problems and a lot of pressure between the population, and the government. This statement is especially true in developing countries. There are a number of problems that generate within a city ranging from traffic, pollution, lack of infrastructure and safety, however one of the most difficult is the insufficiency of quality affordable housing. There is much shortage all over the world and the supply cannot keep up with the demand. The most common practice has been the construction of multi story apartments that house hundreds of units in enormous indifferent blocks. Here the quality of life drops due to the lack of a sense of belonging and ability to control the living area. Instead of increasing the density and decreasing the quality of spaces sloping sites that surround cities should be seriously considered as a viable solution. In general the reason of not building them outweighs the higher cost of the structure, especially the foundation. The reality is that due to the natural composition of the land, sloping sites have additional challenges and should be treated differently, giving them other solutions. However even in sloping sites there has been an insistence of treating them as flat lands recurring to cut and fill techniques and which recent studies have shown major flow. It is the lack of understanding of this terrain, the obsession of treating it as a flat land, and the inability to look beyond the technical difficulties that prevented from the development of sloping sites for affordable or semi-affordable housing. However, can we afford not to use sloping land? Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1.2 Current High density solutions As time passes, the demand for affordable housing will not diminish but will instead increase, and the scarcity of flat land will increase its market value. In addition, the high demand of good quality affordable housing is overwhelming. Fig. l - l Typical Multistory in Sao Paolo, Brazil, 1999 In order to understand the magnitude of the needs, statistic show that in developing countries such as Mexico there is a 6 million housing deficit compared to the registered existing dwellings in 1990 of 16 million. This is almost 40% of housing shortage. In additions there are more than 12 million dwellings that are considered to be in poor conditions, or lack basic infrastructure (INFONTVIT, 1999). This number is alarming, and relates to the conditions in similar cities such as Sao Paolo in Brazil, Deli in India, and Istanbul. In order to house these many people the common practice up to now has been the construction of tower blocks that were developed after World War II. At the time, they had a limit of five to seven stones, which sustained the right proportions, however with the passage of time, the size of these towers has increased in a drastic way, becoming incredible high 2 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. rise buildings. These examples can be found easily in places such as Hong Kong and Malaysia. Fig. 1-2 Private vs. Public Spaces (Newman, 2001) • Private sapc• m itts onl y wi thi n the apartment uni ts, e The interior ci rcul ati on areas and the gr ounds are publ i c, e There is no associ at i on bet ween bui l di ngs and street. Each mega-structure houses a big number of apartment units, failing to offer an individual outlook to the resident offering them a detached, cold, living environment. According to a study made in Great Britain, by D.M Fanning, these kind of living conditions have enormous impacts in the health of residents, affecting especially the respiratory systems for children and young women. Also young women and children are susceptible to develop a psychoneurotic disorder, which is caused by the feeling of isolation and the lack of social contact (D. Abbott, 1981, p.2-3). The ratio of the building to the individual unit is so drastic, that they lack human scale in the relationship to the environment, affecting the resident’s sense of belonging. 3 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 1-3 Relationship of size to crime rate. (Newman, 2001) Location of Crime in Walkups and Highrlses Total In i nterior publ ic spaces On outsi de gr ounds I nsi de apartments 30.0 rsn r 12. 7 100 16. 2 12. 0 14. 5 14. 5 Wal kups (3 floors) Mi dri ses (6-7 floors) Hi ghri ses (13-30 floors) Other studies have shown the direct correlation of larger building size to increased crime rate. As the size of the complex increase, there is less control of access and more anonymity among the residents. This affects the security and the welfare of the residents becoming less friendly and creating a hostile environment. According to H. Newman the two single factors that contribute to crime rates in multi story complexes are the project size attached with the publicly assisted projects name and the relationship of the building height with the number of units per entry (Newman, 2001). This affects the resident’s ability to control his or her own environment. These major flows are apparent, and in many cases completely ignored by local authorities. 1.3 Shortage of Land on Flat Sites Population growth in many urban areas has largely exhausted flat land for building sites. In the United States, the urban population growth has slowed to less than 1.3 percent per year. 4 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. However the amount of land for urban use has increased from 21 million hectares in 1982 to 26 million hectares in 1992. In ten years there has been an increase of 5 million hectares, which include 2,085,945 hectares of forestland, 1,525,314 hectares of cultivated cropland, 943,598 hectares of pastureland, and 774,029 hectares of ranchland (World Resources, 1997). Fig. 1-4 Usage o f Land in Sao Paulo, from 1933-88. (World Resources, 1997) A . 1930 B. 1965 C . 1969 Forest araa The land growth of developing countries is even more alarming, due to the fast urban growth that takes place. According to the United Nations Center for Human Settlements, the physical size of cities in developing countries has doubled in 20 years (1980-2000). (United Nations Center for Human Settlements, 1987, p. 130) This problem is aggravated in major urban centers of developing countries, such as Mexico City, and Sao Paulo, where the expansion of land is occurring at an unstoppable rate. The sprawl is characterized by low- density development and vacant or derelict land, with an outcome of a wasteful use of land sources, higher infrastructure cost and excessive energy consumption and air pollution due to the need for vehicular transportation. An example of this figure is Sao Paolo, Brazil. Figure 1-4 shows the growth of the metropolitan urban core from an area of 180 square kilometers in 1930 to more than 900 square kilometers in 1988. This action took over the prime agricultural land and forestland (World Resources, 1997). The lack of planning has 5 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. resulted in an irreversible environmental destruction, and the endangerment of the poorest of society by pushing them into the most fragile ecosystem areas, without any of the technological, and planning tools to better their living conditions. The deforestation and the loss of natural vegetation resources show the enormous impact the location of cities has in the composition of the environment. We cannot change the course of history regarding the location of cities, nor the past actions of people towards this land. However we have to power to guard the valuable land and protect the ecology, by planing and using it wisely to protect limited resources. 1.4 Current solutions of sloping sites Fig. 1-5 Cut and Fill practice in Tijuana, Mexico, 2000 Current solutions in sloping sites have raised a number of questions in regards to safety, efficiency and logic. The techniques in the construction of sloping sites have been the cut- and-fill grading. This technology has caused building failure in earthquakes due to uneven 6 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. settlement and even landslides. The process takes place in cutting the land and using that land to even out the slope, simulates a flat site, which: • Use the same approach to a flat land • Avoid the usage of more advantageous techniques • Disregard the slope of the site as an asset • Promote failure to the site Promote failure to the building Fig. 1-6 Cut and Fill process, and outcome, 2001 2 7 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. By leveling the land defeats the purpose of building in sloping sites. The removal of so much land adds not only to the cost of the project, but also to the instability of the land causing erosion and landslides. Several studies following the Northridge Earthquake of 1994 demonstrated the problem of uneven settlement failure. The damage of the houses in this condition was apparent and constant in all the studies. Prof. John Steward from UCLA did a study, which showed the weakness of cut-fill techniques. The differential in settlement is too great, and a building sitting in both soils suffered. Another study by Prof. Dimitri Vergun has shown the extreme vulnerability of houses built on cut and fill sites to settlement of fill during earthquakes. He concluded that “ no amount of superstructure strength could (prevent) damage to (the house) when one third of the foundation settles and rotates down slope." When referencing to the case study house during a research investigation of earthquakes performance of wood structures. (Vergun, 2001) Using more common sense, tragedies such as the recent earthquake in El Salvador in 2001 could have less catastrophic outcome, and could have prevented the devastating landslides due to unsafe hillside grading conditions. Fig. 1-7 Landslide after Earthquake, .Las Colinas, El Salvador (Harp, 2001) 8 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1.5 Hillside development The main objective of this study is to adapt the building to the site instead of adapting the site to the building, and minimize grading and retaining walls for a more sustainable environment, designed in harmony with rather than against nature. We have seen how the existing methods of cut and fill work, we understand that there is great shortage of land, and there is great need to find suitable land for the development of housing. Having looked at the need to preserve the flat land for better usage for the environment and agricultural use, developing buildings for affordable housing on the hillsides is a rational idea if we use slope- sites in an intelligent and sensitive way. It is imperative to learn from the past and to make intelligent decisions. There is great concern of urban invasion onto fragile ecosystems as a result of intense land use pressures and poor land use planning. In many countries, especially developing nations, dense colonies of so-called ‘squatters’ already occupy the hillside. They are vulnerable to landslides and soil erosion on water catchments on protected lands, and on land subject to flooding or tidal inundation. People living in these areas are aware of the dangers of nature, and struggle even more with the poor construction and the lack of basic infrastructure, worsening their situation. People already habit in these areas, and year after year there are natural disasters, such as earthquakes, that take away their homes. They need a lasting technical solution that will reduce the danger of living in these slopes and eliminate the cost of the rebuilding. It is necessary to plan in an intelligent way the slopes and hillsides that surround the metropolitan areas. We have seen the great pressure for urban growth, and understand it, however the key is not to lose sight of the big picture. Urban growth and the desire for a better environment have to work together. There are many lessons of the past that due to modern technology, and the ability of humans to condition the natural environment to our needs, that have been lost. It is essential to re think the ways of the past, and create a team that works together from developers, contractors, planners and architects. The goal is to 9 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. accomplish a common ground for the future and not a short time solution that is worse in the long run. The environment is the business of everyone, and the more we take care of it, the better it will be in the future. 1.6 Advantages There are a number of reasons to take advantage of hillsides. From an architectural point of view, this terrain has great potential to create interesting spaces, and break away from the box form. According to Dominique Roillard, the slope becomes a “ catalyst for invention”. (Roillard, 1987) This terrain offers a challenge of re-defining the spatial and technical elements. During the 20m century architects took this creativity even further, by taking advantage of the new available technology. With it, the designer has the ability to take advantage of the unique opportunities that the land offers, and find solutions for the building to be in harmony with the natural environment. As mentioned above, the relationship to the ground is essential, but sloping sites give great advantages for better air. The ability to understand the environment allows the usage of passive solar energy and natural ventilation in the integration of the design. We have the tools and the materials to make these dwellings not only conscious to the environment, but explore the ideas of expansiveness, light, air, openness, and freedom. The self-expression of the design is not the only thing that building on sloping sites would bring. The dwellings have the potential to enjoy maximum privacy, and splendid views. The planner has the potential to learn from the past and really integrate the built environment to the landscape. The natural terrain gives great potential for higher density without the horrible long corridors, and the multiple block buildings. If the architect works with the environment, there should be minimal need for the usage of retaining walls, and the dangers of erosion in the sensitive slopes. Another advantage is higher altitude. This allows better quality air, and ventilation and a better separation from the pollution which one of the major problems as cities grow. The construction is close to the ground, with direct 1 0 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. access from the site to the unit. This setting creates a better sense of community and a better psychological effect, especially for children and the elderly. Los Angeles has been one of the places that due to its natural topography had a number of pioneer constructions in various terrains. On the one hand, it has the sea level flat areas, and on the other hand a mountain chain with great slopes and some valleys. Here one of the earliest hillside constructions to be developed was the Bunker Hill. This was the ideal location, due to the proximity to the center of the city, and the higher altitude, which promoted better air. Later on other hills got developed, such as the Hollywood Hills, Silver Lake, and the Pacific Palisades. In the 20s and early 30s, architects such as Neutra, Schindler and Wright created building that adapted to the site. Sites that were thought to be ‘waste’ hills suddenly became very popular. The dependence of the car allowed Angelinos travel without much concern of distance. Suddenly, the work place did not have to be near the residential area. Hillside became associated with the social class, which correspond to the relief map and the income tax map. The benefit translates to better air, less smoke, and a higher land value (Roillard, 1987). The attitude towards the slope in developing countries shares a different reality to those in Los Angeles. Usually the most valued areas are located close to the center, and as such, the cities grow in a radial form, occupying the center first until it reaches its maximum capacity and growing in a radial way. The sloping sites are usually away from the center, and in many cases, considered to be areas where the poorest live in ‘squatting’ areas. These ‘ waste’ hills are considered to be fragile and unhealthy, due to the piles of trash that are the urban area produces, which turn them into undesirable places. There is great need of housing, and every year the demand augments. The key is to look at examples such as Los Angeles where the sloping sites are habitable and desired. The key is to take advantage of the innumerable possibilities that have been discussed and turn the fate of the u Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. sloping sites around. The shortage of land, the housing needs, and the high market value of the flat areas are some of the reasons to develop hillside construction. It is important to learn from the lessons of the past and use them to work for future development, for the protection o the environment and a better quality of life. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Chapter 2 Introduction - Advantages of Sloping Sites Now that the reason of building on sloping sites has been defined, it is important to explore the positive qualities that could be achieved when building on them. It is amazing how habit can interfere with the flow of new ideas. Up to now, the obsession to duplicate the aesthetics, the techniques and the logic of flat sites on sloping sites has stopped the possibilities of exploring new ideas. It is easy to criticize the actions of the past however it is important to understand the rational of their logic due to the lack of technology and the knowledge to be creative on sloping sites. There were some that explored these options. In 1920's in Los Angeles, there was a group of architects that looked beyond the traditional techniques of flattening the site and created exceptional dwellings on the slope. It has been eighty years since these works have been created, and it is no longer acceptable to see a lack of empathy towards the sloping sites and a repetitive outcome of a box. There are a number of custom-made dwellings that enjoy this creative freedom due to the request of the client, or a constant interaction with the architect. It would be an ideal solution to costume make every single dwelling, however this approach is not possible when building in masses. It would be not possible to take care of every single dwelling with the maximum care, but it would be possible to provide some kind of comfort level for mass-production dwelling. In order to achieve this goal, care should be taken in certain basic elements when designing a project, especially in the understanding of the site's natural forces, the nature of the construction materials and the ability of the builders. It is according to the ability and the craft of the whole team what determines the positive or negative outcome of the design. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2.1 Bad design examples Fig. 2-1 Steep fumes scrapping slopes. (Simpson. 1984; 6) Fig. 2-2 Manipulation o f site with oversize retaining wall. (Simpson, 1984; 8) Fig. 2-3 Flat site houses, manipulated terrace create hughes difference (Simpson, 1984; 6) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Throughout time it seems as if the negative factors have taken over the positive factors in regards to housing construction on sloping sites. One of the determining elements in constructing a building has to do with the visual factors. As mentioned above, the treatment of the site should be determined individually, and should act in harmony with the site. There are a number of buildings with awkward relationships, such as the driveway, in relationship to the rest of the building, or the relationship of one dwelling to the other. These decisions created inadequate volumetric shapes in relationship to the site. The outcome determines the shape of the site using the cut and fill technique and adding to the dangers with this process. There is a lack of visual continuity creating visual gaps, which get emphasized by the heavy usage of retaining walls. This process forces the excavation of the ground, raising the cost of construction and promoting erosion of the ground. One dwelling is several feet below the other, yet there is no differentiation from each other. Each building is treated exactly the same, without considering the actual physical ground that it is standing on. The exterior quality is translated to the interior repeating the same spatial relationships. In order to understand the site, it is important to think beyond the box and explore the various possibilities by combining different elements such as the view, multiple levels, and an intricate yet harmonious relationship with the site. The considerations were so limited that the windows were opened to the adjacent house or the retaining wall or the roof next door, instead of downhill or to the openness. Due to the drastic level changes, landscape becomes expensive to take care. In many instances there is an excess of dead space where the gardens or “ open” spaces translate into steep diagonal areas, creating bigger problems of maintenance and an interference of natural lighting to the unit below. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 2-4 Traditional Hillside Housing (Hetrick, 1974) Building on a slope has a series of obstacles. There is one issue that is clear, which is the higher cost of the substructure than on flat sites. In order to reduce these excessive costs, there is great need to take advantage of new solution instead of repeating the ones that don’t work. Once the realization of other solutions on sloping sites is apparent, designers can incorporate the knowledge and potential for energy efficiency. In summary, the majority of current buildings on hillsides have missed many opportunities specific to their location. According to Simpson and Purdy, there is great ignorance and unwillingness by developers and big enterprises to pay attention to grading in designs and layouts. The drive in building is for instant gratification rather than understanding the long-term gratification (Purdy, 1984). Developers have not been interested in investing on alternative designs that might or might not yield them financial returns. They are aware of current buyers and the housing market profiles that in general are perceived to be conservative. Though there are no compelling evidences that show homebuyers and investors satisfaction with the current resources. There have not been enough studies to show if the potential of massive innovative designs in sloping sites would not be successful for the current needs of the population. What is even more surprising is the little market research done for innovative designs for housing. 1 6 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. This apathetic view has been not only the responsibility of developers, and homebuyers, but also the planning authorities that are in charge of the city by not encouraging innovative designs for affordable housing. The private and the public sectors should understand the numerous possibilities that sloping sites offer in the long run and not be shortsighted in instant gain. It is necessary to consider all the possibilities and advantages that sloping sites have to offer and make additional studies to create a standardization to cut down on the excessive costs. There is a lot of literature in general housing, low-income housing, and planning guidelines, but all of them are on flat sites. There is a scarcity of literature available for the study of slopes and even less for the construction of massive housing on hillsides, adding a better understanding of the third dimension. Construction on sloping sites are available and numerous. What is necessary is to really understand the whole potential and the implications of building three-dimensionally, and further research has to be done. 2.2 Necessary Elements The third dimensionality is an additional challenge in the aesthetic outcome. It involves the study of the mass, the silhouette, the orientation, and the innumerable possibilities of the physical aspects. In the past there was a lack of coordination between the architect, landscape architect, planner, developer, and client to come up with a solution for the layout of the building. Due to the additional cost of the substructure, it needs to be carefully defined through a series of studies in the landscape, the ground, and the external services. The structure should be logical to avoid additional unnecessary costs. Once the exterior elements are determined, it is necessary to pay close attention to the internal scheme, especially the internal layout and the energy efficiency considerations. The shape, the orientation and the type of openings of the house can easily increase energy efficiency and 17 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. reduce the cost of construction. Once the building is erected, efficiency in maintenance of the property is the key to a successful project. Unusual landscape, big retaining walls, and awkward grass location should be avoided. It would be really helpful if planning authorities had the data and the guidelines for all the possibilities in shape and organization in sloping sites (Simpson & Pudy, 1984). This thesis will take a closer look at the compilation of data and guidelines to help planning authorities, and facilitate a system to reduce the cost of construction. I will present a series of guidelines for terraced housing on sloped sites, with minimal cut to the ground. This will reduce erosion and landslides especially during rainy seasons. 2.3 Terrace Housing Advantages This study proposes the usage of Terrace Housing on sloping sites. The dictionary definition of a terrace is “ an unroofed, paved area, immediately adjacent to a house, etc.” and the definition of housing is “ the act of providing shelter or lodging. “ Both of these elements are powerful when used individually. Together they offer the ability to provide a sense of community with identity. Currently there is a need to have a sense of belonging, and multi family housing does not provide the ideal solution to nurture the soul or find peace in their house. Terrace housing offers a variety of positive outlooks. They provide: 1. Human Scale 2. High density 3. Privacy 4. Views 5. Individual Terrace 6. Identity to the surroundings 18 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 7. Sense of community 8. Environmental control Most of the points provided above are the basic elements that any human being should be entitled too. Unfortunately, the majority of the population around the world live in urban settings and mostly in poor living conditions. Terrace housing allows height limits of one to three stories with each story directly connected to the ground. This gives the resident a sense of scale and identity to the surroundings. The logic of the organization of the units achieves high density with a low-rise composition on a site. This provides a solution to the multi story high rise building syndrome of lack of security and lack of identity. The closeness to the ground give children, women and older people a sense of belonging and closeness the natural elements, reducing the physiological disorders in an urban setting. In addition each dwelling has a private terrace, which allow little children to play outdoors without having to worry about safety and traffic flow. The residents are able to enjoy the view, associate with the neighbors while maintaining their own autonomy. The dwellings share a common structural wall, which reduces the cost of material and energy and strengthens the complex by providing more lateral support and stability. The construction of housing on sloping sites allows the usage of flat land for agriculture. Careful planning gives hillsides a safe environment from the natural elements, such as earthquakes and landslides if the structure is carefully designed and erected. This can be achieved only through the understanding of the site and the systematic follow up of basic geo-technical requirements. The cost of the sub-structure can be balanced with the purchase of cheaper ‘waste’ hill slopes that have little market value, and in many places are already the homes of the poor. There are many things to be gained with the construction of terrace housing, especially a sense of community without losing once own privacy. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The selection of materials is important for the performance of units. Also the ability to carefully select the location of openings, such as windows and doors, should be determined by the orientation of the terraces. This precaution determines the environmental performance of the units. The slope gives the opportunity to take advantage of nature, and control the amount of light and air that comes in the unit. It is possible to manipulate the internal environment without the necessity of heating and cooling systems. Since the invention of the air conditioning system, designers have lost the ability to adapt the shape to the environment, creating the same type of building in different climates. We see the same type of box buildings in desert climates like the Middle East and tropical locations as the Caribbean. The ability to adapt has been lost, creating an internal environment full of diseases. According to Prof. Pierre Koenig, since the invention of the air-conditioning system we have created the “ sick building” syndrome. The overwhelming evidences should give us an idea of the numerous opportunities that terrace housing offers, if the goal is to provide sensitive, intelligent buildings. 2.4 Terrace housing in developing countries 2.4.1 Background Terrace housing, as low-income housing in developing countries is not widely used. However, it is broadly known that numerous populated hillside areas surround urban areas. Cities such as Tijuana. Mexico have numerous hills, they are populated by ‘squatting’ neighborhoods, in unsafe conditions. These unsafe settings magnify the possibilities of tragedy during natural disasters, and it is frightening to see how unsound development and environmental practices exacerbate the problem. There are three impacts: economic, social, and environmental. Ail of these can be threatened by natural disasters destroying. Statistics in the past twenty years have shown the capacity for various forms of natural disasters to destroy. As a whole they have killed over 3 million people, and imposed misery in the form 20 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. of injury, disease and homelessness on 1 billion people. In material damage the annual global economic cost average 440 billion dollars. The population in developing countries keeps increasing, and it is estimated that by the year 2025, 80% of the world population w ill reside in developing countries. Sixty percent of these people are vulnerable to various forms of disasters, especially earthquakes. According to Fazal Moin of the Pakistan Red Cross Society, 95% of the total disaster-related deaths around the world will take place in developing countries (Moin, 2001); an astonishing number that is frightening. The negative effect of many disasters is caused by human faults. Given these enormous numbers, it is imperative to put a stop to the failures caused by disasters. The message is clear, development of land and its usage needs to have a high quality standard. Housing, construction, and material standards should provide a safe environment. Laws have to be made in conjunction with the scientific knowledge of the ground and the technological advancements of materials to prevent too much destruction in the built environment. However the best laws are useless if they are not effectively and impartially enforced. Economical aspects can prevent much of the devastation. Developing countries should make the effort to invest in stronger materials, better quality technology and especially a vision for long term effects. It is no longer acceptable to allow so many deaths and devastating destruction. Safety is the factor that needs to be considered by designers and builders. There is a huge demand for housing in developing countries. In Mexico, of the whole population, 32% have the possibility to get financing for half of the cost of their home in the low-income housing sector. However the real need would be 63% of dwellings (INFONAVIT, 1999). These numbers show that most of the population lacks the minimal credit requirements to acquire a house, and resolve to go to the auto-construction sector, building houses in precarious state, and dangerous locations. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2.4.2 Development In the past few decades, just as in the rest of the world, Mexico has a very high demand for housing. Organizations such as INFONAVIT have created means to attract more innovative technology in the building industry. INFONAVIT is one of the leading organizations to help the working class in financing their homes. The working class falls under the poor category, which composes the great majority of the population. INFONAVIT have seen the necessity to raise the building standards for a longer life span of the building, and reduce possible damages in case of natural disasters. There has been little interest in the usage of new technological resources and ideas. There is a shortage of qualified people to train construction workers and there is a lack of resources to improve construction standards. It is necessary to promote different methods of construction, and improve the quality of the construction industry. The quality won't improve unless raising the minimal building code standards, to the level of rest of the world. According to the guidelines of INFONVIT, Mexico is eager to develop a series of investigations to support new thinking and welcome new technology in order to raise the standards and improve the structural safety in housing (INFONAVIT, 1999. Section III.3). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. It is possible to adapt terrace housing in this new philosophy. There are numerous hills that surround urban areas. Many of them are populated but with precarious dwellings. Tijuana is a city that has numerous hills, which serves as a scenario of a case study. Many houses in these areas are self-constructed and lack any kind of technological advancement for the bare essentials. The city has taken a stand to be proactive in the improvement of the quality of living. A number of studies lead by IMPIan (Municipal Institute of Planing in Tijuana), show efforts in various areas of the city, especially in the area of low income housing on sloping sites. (IMPIan, 2000) Most of the hillside homes of Tijuana are self-built and grow as the needs of the residents expand. A number of them use terrace housing in an unconscious way. The advantages of terrace housing are plentiful. This could be a viable option for the government’s efforts in the reduction of tragedies due to landslides. Precarious houses endanger the lives of people, and create a number of problems, economical, environmental, and health. Officially in the rest of the country, there are a current efforts by the government to improve the quality of construction for low-income housing. The effort consists in the promotion of international collaboration to improve the development of technology in the housing industry (Promover acuerdos de cooperacibn intemacional, convenios de concertacibn y promocibn para respaldar e incentivar el desarrollo de tecnologfas para la vivienda) (INFONAVIT, 2000). 2.5 Future possibilities There is a big problem in Mexico, and in other developing countries. There is great demand of housing, great demand of providing, but there seems to be a gap in understanding the basic needs. In an effort to improve this situation, it would be good to work with what is already there. Using the principals of the current situation, and the current knowledge of how terrace housing performs, I believe that it will be easily accepted with the social habits that already exist. Each unit has a private terrace, with the flexibility to be used however 23 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. way the resident chooses to. The unit has the ability to expand out towards as the necessities of the house-hole increases. There is a big market of self-help housing, and even though it isn't exactly the same, terrace houses can take advantage of the technology, the resources, the land, and creates a sense of community. In the market, whatever has economical value is measured according to two different scales: the material and the use value. The material value measures the relationship between the thing with the person. This value has to do more with the market value, and anything related to the materiality of an object or a thing. The use-value on the other hand complies with the needs of the people and the environment. More than economical value, it has a sentimental value, and a need value in regards to survival (Turner, 1976). As time passes, the needs of people change, there is no justification for buildings to stay the same. The family number increases or decreases. With this idea in mind, there is the possibility to self-build the additional spaces, and mold this space (the terrace) to specific requirements of the residents. The migration within individual space, with the existing infrastructure, allows the community to create their own neighborhood and a positive image that reflects their personality and pride. The terrace has the ability to transform, from a private open space, where the clothes can be hanged up and the small children can play without the need to worry about their safety. This open space retains a whole private feeling. Seasons change, years change, and so the terrace house changes with a flexible space, which adapts according to the time of the year, to the natural rhythm of the seasons, and the needs of the residents. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Chapter 3 Existing Similar Structures Introduction - Early Solutions Slope has always been part of every day life for various towns around the world. In many cases the ground configuration has given the town the characteristic and a trade. Yemen in the desert, and many Italian towns in the beginning used the natural environment for survival against other rival towns or to gets away from the reach of health hazardous such as mosquitoes that caused malaria. The composition of the structure in Italian towns was quite complex. The units shared multi story stone bearing walls with wood poles for floor and roof construction, or stone-vaulted roof growing densely one next to the other. Fig. 3-1 Italian Hillside Housing Section (Carver. 1980; 118) 25 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 3-2 Anticoli Corrado, Italy (Carver. 1980; 109) Using structural support as well as a climatic comfort from neighboring units. The irregular growth of units accommodated the site and needs of the town. The streets were narrow to control the natural elements by allowing only a certain amount of light inside. There are many lessons of the past that can be used in the present construction methods, that is the essential qualities of the functionality of the town (Carver, 1980). Fig. 3-3 Wolf House, Catalina Island (Rouillard, 1987; 50) 26 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Modem times brought other kinds of advancements, especially technological. Architects in the 20's such as Rudolph Schindler, Frank Lloyd Wright and Richard Neurta designed a number of experimental projects in the hills surrounding the Los Angeles area. Many of the hills were considered to be wasteland, and unsuitable for construction of buildings. Schindler, in particular, gave the hill considerable credit. He did not believe in molding the site to the building but followed the principal that I’m implementing in this study, shaping the building to the site. He approached his projects with great concern for the site, considering it as the canvas of a painting where every comer counts. He said: “ the space house as a space form becom(ing) part of the room formed by the lot, the surroundings, contours, and the firmament” (Rouillard, 1987, pp.45). However before any thing, he thought of the sloping site as air, light, space, and a poetic idea in which all the intangible elements, in conjunction to the hillside, provided a new meaning to the atmosphere of architecture. Instead of ignoring the multiple possibilities, he embraced the challenge of the site and balanced it within his design. The principal concern was to embrace the contact of the house to the land hardly touching the ground bellow, in a vertical relationship. The Wolfe house, built in Catalina Island, is one of the finest examples to this principal. According to Schindler this house is “ standing on tiptoe” (Rouillard, 1987, p. 51). showing full respect to the hillside. In addition to this new theory, he got rid of the traditional basement. He said that the basement was a limitation to the past restrains, furthermore adding his lack of understanding of that specific space, which is “ expensive, unventilated, moist, dark room in the ground (p.46). Schindler, was one of the firsts to venture into these modem views, emphasizing the desire to respect the ground to the fullest, showing great understanding of balance with the environment. 27 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 3-4 Rational fo r respecting the ground fo r cross ventilation, and foundation expression (Roullard, 1987; 52) Adherence Suspension Hovering Layers in suspension r C o . \ There is a new expression between front and back, which translates into top and bottom. In the bottom, instead of cutting and filling the ground, there is a connection to the ground through a thin slab of concrete and supported with columns, which raise the living space, offering complete privacy. By detaching from the ground he created an illusion of absence in the support of the system. The biggest challenges were the cantilevers, the open wide span, and the open space-forming surfaces of screening thin walls. The Wolfe house is a fine example of earthquake resistance structure. Since its erection in 1928, it has withstood several earthquakes without any cracks, creating a balance of the instability of the slope, 28 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. and the stability of the construction. (McCoy, 1953. p.14) The technological advancements are many since the publication of McCoy’s paper in 1953, however this article proves the theory of balance for stability with the environment. 3.2 Case Studies The study of hillside housing has not been as extensive as housing on flat sites. Though reduced in number, there are good examples of hillside development in recent times. Many of those have served as examples to further the knowledge of terrace housing. They are located all over the world and emphasize elements that have been instrumental in this study. The most important are the elements of human scale, the respect of the natural landscape, spatial quality within the unit. The past has given us many lessons, and the key element to achieve harmony is the clear understanding of the natural elements especially the understanding of climate, ground, local construction, and the ability to adapt to it. 3.2.1 Hermosa Beach, CA Terrace Housing This housing complex in Hermosa Beach, California, designed by G G Schierle, was planned as a Commercial/Residential Development, and ended up as a residential Development exclusively. The developer was intending twenty-five units on the site based on existing zoning, and believed to achieve the maximum density possible. With terrace housing, the architect was able to raise the density of the site from twenty-five to thirty-three units without the overcrowding of multistory complexes. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 3-5 Hermosa Beach Axon (Schierle. 1981) Fig. 3-6 Hermosa Beach, front facade (Schierle. 1981) The project is six stories high, from the bottom to the very top of the site. However the key to this project is the accessibility of every single unit from the exterior level or by climbing one story up or down from the street level. This is a Type V, lightweight wood frame project. Due to its size it was necessary to include two-hour fire rated party walls. This allowed better security in case of fire and achieves better sound insulation performance. The project is designed based on the architect’s philosophy for sustainable architecture: to conserve resources, provide structural safety and adjust the building to the site rather than adjusting 30 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. the site to the building, to minimize grading and retaining walls. The terraced configuration follows the natural slope, with walls arranged on a consistent module for vertical line up of structural walls that provide a clear load path for gravity and lateral loads. Fig. 3-7 Hermosa Beach, balcony and planters (Schierle, 1981) Each unit has two large decks for open space almost as large as the land covered by buildings. Trellises provide sun shading for natural energy efficiency. Combined with planter boxes, they also provide privacy for each unit from units above. On the rear, the structure is raised from the ground to allow gross ventilation to eliminate the need for air conditioning; this also was intended to reduce energy consumption. Party walls between adjacent decks provide privacy from adjacent units. The party walls are angled toward the pacific view and to shield units from westerly glaring sun. The Hermosa Beach terrace housing was built in 1981 and took 2 years in construction. The ability of the architect consisted in the understanding of the terrain, and minimizing the structural cost, through 31 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. minimal excavation in the ground. The maximum privacy per unit allows individual freedom, nonetheless this complex give a sense of community with a low building profile. Fig. 3-8 Hermosa Beach Cross-Section (Schierle, 1981) 3.2.2 Rokko Housing in Kobe Japan Fig. 3-9 Rokko House Axon (Great Buildings. 1999) The architecture of Tadao Ando combines the traditional Japanese with Western modem architecture. The main characteristic of his work is the masterful usage of concrete, and the usage of the grid as the core of the architecture with a clear understanding of the landscape 32 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. and the void within the architecture. His work has a special meaning within the chaos of modem Japan, and due to its mountainous topography the majority of its population is densely packed into the scarce flat areas. The inhuman living conditions represent a contradicting juxtaposition to the traditional believes of housing. In Japanese culture the word for a traditional house does not just mean the building but the whole site in which the building is contained. Rokko Housing is one of the most important examples of integration of building to nature. Rokko housing was finished in 1983, overlooking the Osaka Bay in a sixty-degree hillside with a panoramic view. While the units appear to be uniform on the outside, each one has a unique interior. Built of reinforced concrete with a rigid frame, the units are embedded in the side of sixty-degree sloping hillside. Each of the houses has a terrace and direct access to the outer level, which encourages the revitalization of social interaction. This building explores the possibility of searching the past ideals. Ando rejects the rampant consumerism visible within much of today's architecture. He responds both sensitively and critically to the chaotic Japanese urban environment, but maintains a connection to the landscape. Fig. 3-10 Rokko Housing, aerial view (Great Buildings, 1999) 33 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Although Ando rejects cultural fads, he uses materials and forms to incorporate the materialism of modem society into his architecture. Accordingly, his concrete and glass buildings reflect the modem progress underway in both Japan and the world. The desire to create a sense of community together with the understanding of the power of the natural surroundings express two powerful elements that are essential in a livable community. It is the respect of the public vs. the private and to the surroundings from where this project draws its power. 3.2.3 Stepped Housing, Zurich, Switzerland Fig. 3-11 Cross Section and Site plan (Abbott, 1981) o 15 m A Sect i ons D Si ts pl an 34 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. One of the most notorious advantages of hillside housing is the access to view. The architects Stucky and Meuli explored the various views of Lake Zug, taking the most advantage of the northwest view. This project takes advantage of three sides, creating three balconies (north, east and west). The project is on a site of 32 to a 37-degree slope, which is considered to be very steep. The careful study towards the view, together with the generous usage of landscape give this project an impression of ‘hanging gardens’ (Abbott, 1981). This amenity provides a pleasant view and most importantly human comfort with shadow. The large balconies provide a sense of privacy by avoiding overlooking from one unit to the other as well as direct light infiltration. Just as the projects above, terrace housing allows great density with a human scale. This configuration works extremely well physically and especially psychologically. Fig. 3-12 Facade (Abbott, 1981; 139) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3.2.4 Environmental Residence The architect Murray Milne designed this project. It is located in Malibu California and works extremely well with the natural environment because it takes advantage of it’s location and the climate. It faces the ocean, which allows the usage of its natural breeze. All the openings are well thought in order to take the most advantage of the sun. The balconies have overhangs that shield the rooms from overexposure to the sun. The overhang balcony is so well understood according the latitude of Los Angeles, that the edge of the sun hits the edge of the glass door during the equinox. The high windows are opened on top on the edge of the corridor. This light pierces into the bathroom through a semi-opened wall that serves as partition. This simple move lets the natural light illuminate the bathroom avoiding the window-less room. The internal temperature is very constant throughout the whole year, avoiding the usage of heating and cooling devises saving energy throughout the year. The terraces are very generous in size and ensure privacy from one unit to the next. Fig. 3-13 Malibu Front Faqade, 2000 36 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Chapter 4 Housing Needs in Developing Countries 4.1 Background Sustainable housing is the need of any human being as the basis to for the search of inner peace. The Nucleus of the family starts with the home. It is in this sheltered environment where humans seek comfort, re-nourishment, and peace. Studies show that owning a house represents the most important accomplishment for most people in their entire life. The national nucleus represents the primary source and reason to work, and the biggest incentive to better the quality of life. In Mexico during the past three decades, housing has become one of the only saving sources in the entire country. Almost half of the national savings are provide for dwelling units. Looking at the general tendencies, it was established in 1972 a mandatory requirement for all the foremen to support the National Housing Found and establish a financial system, in order to allow the working class to obtain low rate credit and purchase their own dwellings. The effort has been slow, in 1983 it became a constitutional right to be an individual guarantee. Since then, there has been a lot of improvement towards the awareness in housing needs among the population, yet there is a long way to go. During the 1995 to 2000 period a lot of effort was focused on the improvement of the quality of living standards for planned developments. These actions have reduced the self-construction market, reducing the liability and improving the living standards. During this period there has been great awareness in regards to the construction in risky terrenes. During this time the re-distribution of ‘squatting’ neighborhoods into planned projects became one of the priorities. There is a new effort to combine the private sector in the fight against shortage of housing demands. The need of housing is clean yet the most important factor is the realization of actual needs for the specific geographic locations in order to avoid unsuitable dwellings that instead of helping endanger the lives of 37 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. the residents. The key promulgation is a dear understanding of the needs of the people in the social culture and clear connection to its surroundings. 4.2 Housing Characteristics in Mexico Fig. 4-1 S elf constructed community on a slope. Tijuana 2001 With time there has been change an progress. Since 1970 there has been great improvement. The majority of the dwellings have between one to three rooms per dwelling without counting the kitchen. In only ten years since 1990, there has been an increase in 38 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. housing with two or more bedrooms. Though the number of inhabitants per dwelling has been reduced throughout the years, the numbers of three bedroom apartments have increased drastically. In 1970 there were 30.9% of housing units that had three bedrooms or more. In 1990 this number has increased to 65.5%. As a result, the average density per dwelling decreased from 5.8 occupants, with 2.6 people per room, to an average density of 5.0 occupants, with 1.5 people per room, increasing the living standards within the units. Quality does not translate into space only, but in the quality of the craft, materials, structure, and relationship to the surroundings. Fig. 4-2 Characteristic o f a typical facade, Tijuana. 2001 In relation to the construction materials there has been an increase of industrialized materials in relation to natural ones. In 1970, 44.1% of dwellings used as interior walls, concrete block, brick or stone. By 1990 almost 70% of the dwellings used this materials. In regards to the ceiling materials, there was an increase from 34.2% to 51.7% with concrete and brick, as well as drastic decrease from 41.1% to 19.6% of soil floors. (INFONAVIT, 39 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1999) There has been a lot of progress in modernizing the use of material, allowing standardization of construction quality. 4.3 Current Practice Fig. 4-3 Tires as a main feature, Tijuana 2001 The problem of housing starts with the lack of organization among different sectors. Mexico has extensive land for new development of housing. What is lacking is a master plan towards future growth and specific needs of the community. There is a lack of organized development near the urban areas, which makes it very difficult for the public and private sectors to take any action to provide dwellings. Ironically, the poorest people live the 40 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. farthest from the center, and where all the jobs are located and where the public transpiration is scarce. The unavailability of reliable public transportation makes it even more difficult and a daily drudgery. Yet, housing needs are real and need to be fulfilled, pushing people to invade unsafe and inadequate terrain, making it even more difficult to develop, and hard to rehabilitate and reconstruct. It is therefore imperative to regulate these lands, and provide areas suitable for the development of dwellings. Historically most of the population lived in precarious conditions with only one room to fulfill all needs. It wasn't until the 1920s when modem dwellings were established and the introduction of concepts such as the division of spaces, the assignment of private, social, and open space were introduced. The most important advancement during this period was the rationalization of the functional spaces, especially in terms of the sanitary areas, raising the health conditions for the whole population. 4.4 Developing Process The developing process of modem houses has taken time. Even now, in low-income areas, squatting areas, and rural areas, the one-room dwellings prevail with some kind of improvement. The transformation to modem homes is similar to the rest of the world. A minimal modem home is considered to be composed of a living room, dining room, kitchen, a small patio, two bedrooms and a bathroom. The reality of the Mexican economy has pushed the envelope in finding better solutions to fit reduced spaces, such as the versatility of the bathroom area. These new dwellings have adapted European models in adapting individual rooms for the WC and the separation of the sink by incorporating it to the corridor area. Just as for the bathroom, there is room to improve the kitchen area, for there has been a lot of reluctance to use the integrated kitchen; a model used greatly in the US. According to the INFONAVIT, less than 10% of the dwellings sold us this efficient system. 4 1 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The one single factor that most Mexican families desire, according to market studies, is privacy, and a place of social gathering. According to the study, 70% of the surveys gave privacy priority over security and functionalism. (URBIDATA, 1993-94) This is important to note, because it criticizes the usage of high rise and multifamily buildings. This desire for privacy includes the usage of a wall, or something that delineates the boundary of their own property, and allows them freedom in their own property. An element, such as the patio and/or the garden, goes hand in hand with extensive social interaction as an integral part of Mexican society. This area represents the social and gathering area, where people share experiences with one another. In many instances, this area is so important that the garage space destined for the car is converted into this patio or some kind of gathering area. This open area is used for very day activity such as hanging clothes because it ensures privacy and freedom within the space. Fig. 4-4 “ Tendedero ” Cloth hanging area, Tijuana 2001 42 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 4-5 Combination o f Tires and "Tendedero”, Tijuana 2001 4.5 Row Housing Row Housing has been one of the most accepted solutions in the construction of housing. During the 1980’s 45% of the housing construction took in the whole country was row housing, with only 10% of multi-family construction. This system of construction has been successful due to the individual privacy that these units offered. During the 1990s the horizontal construction gained terrain by increasing the construction to 60% (INFONAVIT, 1999). 4.6 Materials The quality of construction materials and health conditions has improved in a drastic way. In the past the majority of the floors were covered with sand. Now only 13.4% of the houses in the study have soil flooring. The rest of the floors are covered by some kind of material to ensure healthier conditions and ensure a longer life span of the material. The technological 43 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. advancements of different materials around the world have been astonishing. One of the biggest reasons has been the transformation of the different urban areas, and the fight of natural disasters. In Mexico, up to the 1920’s the predominant material was adobe, clay and rustic wood for the walls, and the roofs were covered with the natural vegetation such as palm leaves, and in the north flat roofs with mud and hay mixture. 4.6.1 Concrete Block The material with the most acceptance in Mexico has been the Portland cement. Currently the usage of concrete block and brick are used for walls, and concrete slabs for the roof and the floor. Since 1970 brick and concrete block have been the most common materials used. In 1990 these materials dominated the construction industry with 70%. The footings are built with reinforced concrete block, and the walls are built with brick. Statistics show a surprising usage of concrete slab in addition to concrete block or brick walls. 4.6.2 Brick As mentioned above, the usage of brick dominates the building industry. Now a day, mainly the small rustic shops dominate the brick industry, and the quality of the material varies tremendously in accordance to the individual technological development. However, due to the harmful and the pollution qualities of this material, there have been many changes in its creation, thanks to the National Environmental Control Agency. 4.6.3 Wood The construction with wood has been limited to the rustic construction in tropical and mountain areas. The lumber industry in Mexico is still very scarce. It exists in border cities such as Monterrey, Tijuana and Cd. Juarez among others due to its proximity to the United States. However since the 1960s the National Lumber industry has grown due to the 44 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. introduction in low-income houses known as the 'tejabanes’. This solution was accepted for a period of time due to the low cost, and rapid construction. Due to this pilot project, the lumber industry increased its production 8% in the 1990s. There is hope for this type of construction thanks to the Free trade agreement with Canada and the US, if an economical solution is found. However the most important factor is to educate the population of dwellings of wood due to their lightweight resulting in reduced seismic forces. 4.6.4 Alternate Materials There are natural materials from the past that are still used today. Among these, adobe still plays an important roll. Adobe is highly used especially in wall construction, with a combination of roof structures composed of concrete, shingles, hay, corrugated metal, and cardboard. Due to the development of concrete, there has been less usage of adobe, however many architects are trying to revive this tradition. Besides adobe, there are a number of materials derived from nature, other than wood, especially in the construction of the roof, such as palm and different types of hay. However, un-reinforced clay is a very poor material to resist earthquakes. 4.7 Technology With the passage of time, the technology in Mexico has advanced, though limited. Most of the construction is done in traditional technology, and pre-fabrication is very rare. As mentioned above, the primary materials used now are brick and concrete. Perhaps the immense change has to do with the substitution of a flat roof by a reinforced concrete slab. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4.7.1 Pre-fabrication The Pre-fabrication industry in Mexico started at the end of the 1940s. There were many buildings constructed with this technology, such as offices, hotels, hospitals, and schools. However, there has been a lesser impact on the housing industry. There are only few Housing projects that have used prefabricated materials. The most successful project in the country was the complex Santa Fe, built 1954-1957. The walls were pre-fabricated. However, prefabrication did not advance as much afterwards, until 1963. The housing complex San Juan de Aragon, consisting of 970 houses used pre-fabrication, included the electrical installations and plumbing within the module. With this system, they were able to built 12 houses per day. However, as prototypes were built and tested it did not create a lot of excitement among the construction industry. In the prefabrication Seminar of Latin America (1967), in Copenhagen Denmark, experts suggested that: “ Countries where there is a lot of hand labor, and a lack of capital, should stick with the traditional systems of construction, as opposed to the industrialized construction that requires more capital and less hand labor." (INFONAVIT, 1999). 4.8 The Future of Housing The construction of housing contributes greatly to the economy of the country. It generates many sources of employment, and improves the quality of life. There has been great effort in the construction of affordable housing. However there is still a lot of ground to cover. During the period of 2000 to 2050 the demand for housing will be approximately 20 million units due to the demographic constitution of the country. Due to this high demand of housing it is imperative to use new techniques to better the quality of construction. Find ways 46 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. to maximize the usage of the land by taking advantage of the sloping, left over sites that are within the city or surround the metropolis, and have a high standard of quality control. 47 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Chapter 5 Soil Behavior and Land Treatment 5.1 Introduction Landslides are the result of slope instability, a process that occurs in different ways: slowly or suddenly. There are many internal and external factors that create landslides, such as: 1. Excavation 2. Undercutting the foot of an existing slope 3. Improper surface and subsurface drainage 4. Tunnel collapse of underground caverns 5. Surface and subsurface erosion 6. Earthquake 7. Blasting that cause liquefaction of the soil There are two types of experts that deal with the stability of the soil: geologists and the geo- technical engineers. The main interest of geologists is the study of the ground. They deal with the movement of the ground, and the geological and hydrological features of the ground. Geo-technical engineers focus on the study of soil type and its behavior. They analyze the maximum slope height and angle in terms of safety factor. They are the people who determine the dangers of the site, and whether it is possible to build on it, considering the vulnerability of the land. Both, engineers and geologists, are crucial in the beginning of projects, especially on hillsides. Failure to consult these specialists can result in tragedies. It is intelligent to establish an alliance with competent professionals and the designer. Soils test results should be compatible with the type of structure desired. This action determines the safety and the requirements needed for the development of the specific site (Fang, 1997, P. 485). 48 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 5.2 Slope Stability analysis Historically there have been a number of landslides with tragic outcomes, especially in developing countries. Some of the most devastating tragedies have been the mudslides in Venezuela in January of 2001 and the El Salvador Earthquake in March of 2001. There are a number of questions of why the land failed in these tragedies. It is necessary to further analyze nature of landslide process. Landslides are divided in two categories, external and internal. Loads create some of the external causes, which includes excessive saturation, seismic or blasting vibration and removal of vegetation with soil stabilizing roots. Other elements that cause landslides are the natural environmental phenomena that cause unbalance in the ecosystem through rainstorms, dry-wet cycles with catastrophic effects on various soil types. The internal causes are bestowed by the external, working in a full circle. Landslide is analyzed two methods. One is the limit equilibrium approach, in which the failure surface has as many forms as straight lines, circular arc, spirals, or irregular shapes. Fig. 5-1 Pre-failure stages diagram associated with landslides (Fang, 1992; 498) tla « The selected area or free body starts from the slope, from a known or assumed set of values of the forces acting on the selected area. It then calculates the necessary soil needed to bring equilibrium to the selected area. The limit analysis method uses the criterion of yield and its associated flow rule. (Fang, 1992, pp. 498-9) The major advantage of this method is 49 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. that it provides a close-form solution, which is visual, allowing engineers to picture the mechanics of the failure before it is too late. Fig5-2 W = weight ofsoil wedge S =shear strength ofsoil along failu re surface R = Result (Feng, 1992; 499) (a) Foreaa Acting on Earth (b) Eorca Olagraa S iop« ta t a c t r s tt s iite « » » te a i e s tic r r t t i s Fallura Surfac# 5.3 Major Problems for Landslide One of the principal forces that cause landslides are sudden external forces such as earthquakes, which are the most devastating natural forces that cause damage. According to Yen and Wang’s report, within the most common failure types are the shallow hillside slides. Usually the shallow depth is less than 2m in proportion to the length, approximately 10m with a vast amount of cracks on the top of the slope (Fang, 1997). The cracks should give a sign for the sudden failure. Deep slope failure is caused by soil liquefaction. The excessive clearing of woods and vegetation in sloping sites magnifies the instability of the ground. The vegetation adds to the stability of the ground, because it creates a weaving texture that adds to the strength of the surface. Over-cutting or over-excavating hillsides is one of the major forces that cause landslide. Unfortunately, the over population of the urban centers has promoted the development in of any kind of land, without a thorough study in future effects. Over cutting on the slope promotes deforestation and with it erosion of the land, which after some time, stops the natural cycle. The ability of mankind to produce any mark in the natural landscape can have catastrophic consequences. In order to manipulate 50 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 5-3 Bio-Technical ground cover, (Garry, 2000) Fig. 5-4 With the passage o f time. the land to whatever shape is desired, it is common to build massive retaining walls. This action not only increases the cost of construction, due to excavation, but this action increase the fragility of the land by “ butchering" the hillside, and promoting the instability of the land. Unfortunately this method is widely used. The most important problem results from building on cut-and-fill sites. Differential fill depth results in differential settlements that cause failure in earthquakes. 5.4 Landslide Prevention and Control 5.4.1 Bio-technical Stabilization There are many widely used techniques to prevent and control of landslide and erosion on sloping sites. According to Professor Donald Gray, “ Biotechnical groundcovers, soil bioengineering and landform grading have greatly increased our ability to control erosion 51 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. and sedimentation” (Gary, 2001). There are two measuring technique categories for erosion control in the Untied States. One is to measure the erosive forces and the velocity of water or wind flowing directly over the soil. The other is the measurement to increase erosion resistance through the stabilization of the soil. The process covers the surface of the ground with a protective layer, such as grass, straw mulch, and bio-technical ground covers. The dense grass and herbaceous plants cover the ground, and in the long run appear to have the same effect as the natural process. This technique has proven to be the best long-term protection against erosion on the surface. Surface stabilization goes hand in hand with environmental control, and provide an opportunity to work with environmental landscape. Plants, leaves and foliage intercept raindrops, the stems and roots filter sediment out of the runoff, and the roots reinforce the soil and tie the particles together. The stems and foliage increase surface roughness and slow the velocity of runoff. However, vegetation itself cannot do the whole job. The system takes time to adjust to the ground and the climatic conditions. The downside is the initial vulnerability to failure and drought. It also has a limitation to the velocity of the wind in the ability to withstand the changes in temperature and transfer when used in temporary channels or grassed waterways. Another downside effect is the ability of the vegetation on very steep slopes. This technique faces many restriction and new findings and technological advances have been established to overcome these limitations. In order to strengthen the surface of the ground, in steeper sloping grounds “ reinforced grass” has been widely used. In order to achieve a stronger ground the grass surface is artificially enhanced with a combination of grass and an open structural coverage such as mats, meshes and interlocking concrete block which increase resistance against erosion. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 5-5 Reinforced grass process (Garry, 2000) Fig. 5-6 Fully grown after some time Bio-technical composites are typically composed of non-degradable elements, which in time combines with the organic elements, creating very strong surfaces. As a goal, Landform grading attempts to imitate nature. The major difference between the bio-technical process and real nature, is the straight line that the artificially created slope boasts. Natural slopes have the ability to adapt to the intricate connections and transitions that only nature can imitate. The complex and symmetrical patterns covered by the artificial vegetation are the result to the necessity to adjust to hillside hydrogeology. Shrubs and other woody vegetation that grow on natural slopes tend to cluster in valleys where moisture is more abundant. Man made hills lack the ability to hold the soil, when not uniform, therefore random patterns should be avoided. The location of vegetation such as shrubs and trees should be carefully located only where it is necessary to fulfill the job of holding soil. The manipulation of the slope should be precise and well studied. The effectiveness can be controlled when placing 53 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. shrubs in concentrated areas along the natural drainage, or in concave areas. On the other hand in convex areas, grasses or more drought tolerant herbaceous vegetation should be planted. The understanding of the new technological advancements allows the interaction between science and technology, and realizes the strengths that a partnership offers. Further studies and mutual understanding between the different professional fields. 5.4.2 Stabilization with Tires According to the 1995 statistics, California generated 44 million used tires during that year. Out of those, 21 million had no economical value and were added to the increasing problem of waste (Luna, 1997, p. 3). In 1993, many landfills in California did not have the capacity to store the tires. Tires are not able to disintegrate. Fig.5-7 Retaining w all composed o f tires, Tijuana, 2001 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 5-8 Tires used as planter and decorative elements, Tijuana, 2001 In fact, they posses so much value that should be recycled. Over the years governments in southern California have tried without much success to promote the recycling of tires. Developing countries re-use discarded tires for various uses. Cities such as Tijuana have a very big market for this product. People are compelled to find creative uses for inexpensive items like tires when they are faced with a scarcity of valuable resources. Developing countries and especially squatting communities use tires for the creation of pathways in steep slopes, which avoid direct contact with the soil. This technique is repeated to make connections between adjacent homes. Tires are also used as retaining walls, creating a thick wall, resistant to ground movement. Stabilization with tires unifies two different markets, and helps the environment by recycling the excess material and helping the developing countries in providing them with inexpensive materials for their basic needs of shelter and survival. In many cases, the tires adapt a sculptural quality, such as the enhancement of landscape by combining the tires as planting pots in various shapes and sizes. With the lack of resources, people have learned to combine minimal construction materials for the maximum benefit. 55 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 5-9 Tires used as the main circulation through a street, Tijuana, 2001 This technique has been used for a long time and has proven it’s structural capacity. It would be enriching to educate people in the exploration for the numerous possibilities of new creations and exciting designs. The tire-made retaining walls have survived numerous storms with great success due to the ability to release water pressure, while other “ stronger” materials have failed. The ingenious ability to improvise with any kind of material in any circumstance has allowed individual expression in the individual parcels. This technique has helped to minimize brutalization of the land, avoid massive erosions and prevent tragic landslides. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 5.5 Disasters Fig. 5-10 Damage at foothill ofslope, Hong Kong. (Abbott, 1984) Fig. 5-11 landslide damage (Abbott, 1984) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The fragility and potential for disasters emphasize the great need to ensure the stability of slope and avoid tragic consequences. It is crucial to understand the principals in geo- technical engineering, which encompasses the understanding of geology, hydrology, history of the site, and topography. The lack of understanding to these factors has resulted in great tragedies such as the over excavation at the toe of a hillside in Hong Kong in 1972, which, during raining season, especially heavy rain, caused landslide that demolished buildings and killed nearly 70 people. Fig. 5-12 Luxurious Development on top o f the h ill after Earthquake. E l Salvador 2001 58 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 5-13 Buried houses after Earthquake, E l Salvador, 2001 A more recent tragedy occurred during the January 2001 Earthquake in Las Colinas, Santa Tecla, El Salvador with a magnitude of 7.8 on the Richter scale. About 200-300 houses were buried in a landslide 15 feet deep caused by the Earthquake. Hundreds, perhaps several thousand, people were buried, including approximately 40 workers at a construction site on the hilltop. The majority of reported deaths occurred in this particularly vulnerable hillside area. The major criticism is that this tragedy could have been prevented, and was a manmade factor, not a natural disaster. Residents of the area had been struggling for years to stop development on the hillside, which is home to a Balsam Forest. The hilltop site was going to be a major luxury housing development. For years, CESTA, the Center for Appropriate Technology, an environmental organization warned developers and the construction department about the dangers in the development, deforestation and destabilization of the hillside, which lead to landslides precisely in the area in which the disaster occurred. 5.6 Cut and Fill Up to now one of the major techniques for hillside developments has been cutting and filling. This practice has been one of the major causes for brutalizing of the hill and major disasters in the past. One major cause has been the treatment of sloping sites the same as flat sites, 59 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. by leveling the site. In response to the Northridge Earthquake failures, Prof. John Stewart of UCLA conducted a study that shows homes on fill sites were more damaged than those on cut sites. The worst scenarios were those at the interface of cut and fill. The main reason is the differential settlement of fill land due to differential depth. The differential settlement causes cracks and major failures in buildings. In addition to the unstable soil, the cost of grading is very high, and the footing rest in the soft fill area. Cut and fill also has a major impact in the environment. It becomes a potential danger to the lives of people living in those dwelling or in foot of the hill; it may trigger a variety of landslides. The key factor is to understand the physics of the ground, and respect the nature of the site. These cautions w ill avoid landslides such as: 1. Fall 2. Rotational slide 3. Transnational block slide 4. Multiple rotation Slide 5. Multiple translation slide 6. Compound Slide Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 5-14 Types o f Landslides, Feng, 1992 original ground level area of fill area of cut Cut and fill alopes 1. Fall y r _ . 1 ' ' 2. Rotational alide 3. Trananational block slide 4. Multiple rotation alide S . Multiple tranafation slide 6. Compound slide 61 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Chapter 6 Mexico - History and Background Nowhere in the world do two countries as different as Mexico and the United States live side by side. By this I don’t mean physical differences only, but most importantly nowhere in the world tow neighbors understand each other so little. More than the levels of development, these countries are separated by religion, language, race, philosophy and history. The US is a two hundred-year old country taking big leaps to the future in regards to technology, economy and development where as Mexico is several thousand-year old country, clinging to the past, making slower changes into the future. These differences could become allays if they leam from each other. The economic richness that the US has in comparison with the economic poverty that is only apparent when crossing the border. However, housing necessities are the same in both countries in different levels. Perhaps they should work together in this issue. The history that Mexico possesses could benefit from the technology and the new methods that the US has. Mexico has the land, the people and the diverse terrain, having a coastline almost 10 thousand km, high rugged mountains, low coastal plains, high plateaus and deserts. Mexico’s heritage has been translated through the culture, the history, and most notoriously through the architecture in our times. This architecture speaks about the roots of the people in an aesthetic way. However it also should speak about the past experiences about things that worked in the past in accordance to function. Agustin Hemdndez is one of the most influential Mexican architects of our time, throughout his practice he has combined technology with the cultural heritage by adding elements of the per-Hispanic, the colonial culture and the modem technology. He says that architecture should "project something that expresses our place, our country, but at the same time the universe... the architecture of today should have elements of the present, the past, and most importantly, a lot from the future." He further adds that “ it is impossible to 62 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. import a culture, this can only grow with our own roots, and with the buried heritage to give us the drive for the authenticity.” (Hernandez, 1999, p.41) 6.1 Mexico 6.1.1 Location Mexico is a privileged country with a number of natural resources, a variety of terrain ranging from rugged mountains, coastal plains, high plateaus and desert with a variety of climatic conditions. Fig. 6-1 Map o f Mexico (National Geographic, 1996) Gmlf o f JWcjcIco P a c ific O ce a n 1 H M 6.1.2 Demographics Currently, Mexico has a population of 99 million. Young people with working and housing needs compost the majority of the population. In the past thirty years, the demographics of the country have changed. According to census, in the year 2000 the average age was twenty-two years of age. In 1990 the average age was nineteen years of age, and in the 70s 63 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. the average age was seventeen. This shift in age has to do mainly due to birth control, reduction of child mortality and lengthening in life expectancy, from 50.8 years in 1950 to 72 years of age in the present. The recent numbers shows the change in age population concentration. The range of dependency among the population is greatly reduced. The dependency age is defined as less than fifteen and more than sixty-five years of age (INEGI, 2000). Table 6-1 Population Division According to Age Group Age Range 1990 2000 <15 38.3 34.0 15-64 56.8 60.6 64< 4.1 5.0 Fig. 6-2 Population Distribution 1970-2000 (IN E G I, 2000) u is « .• * .• i i u u u u te e 64 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. This phenomenon is important because it shows that the country is passing through a period with less dependency. This demographic process opens a window to strengthen the education and training of the economically active population and achieve social and economical strength in the long run. 6.1.3 Education Literacy The education level of a country helps to determine the quality of life of the population. In order to understand the reality of a country, it is necessary to understand the literacy level and the education level of two groups within the population: 6-14 years of age and more than 15 years. Currently the percentage of literacy among the 6-14 age group is 87.2%. Over the age of 15 there is a literacy percentage of 90.3%, which represents the highest percentage of literacy level in the history of Mexico. Unfortunately there are around 6 million of people who are illiterate among the population. 53.2% of them have the age of 50 or more, and reside in rural areas (INEGI, 2000). Basic Education Laval There is an active participation in school in the 6 - 9 age groups of 95% participation. This percentage is reduced to 90% in the 10 -14 age group, 46.7% in the 15 -1 9 age group and 17.7% in the 20 - 24 age group. The reasons for school abandonment are due to personal reasons such as lack of interest and discipline, lack of school facilities close by and especial economical reasons. With age advancement the reasons for school abandonment increase notably due to marriage and economical reasons. Figure 6-2 shows the age groups and the reasons of school abandonment in greater detail. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 6-3 Education Abandonment among 6-29 age group (INEGI, 2000) Education Laval Due to economical reasons, education becomes secondary. There is a drastic reduction of school attendance among the population over the age of 15. In the year 2000 only 7.6% attended middle school. This number reflects the education level of the population who had irregular schooling with a lack of continuous schooling or lack of instruction. Among the population with education of high school and technical education there was an increase from 14.3% in 1990 to 16.7% in 2000. A similar increase was perceived in the University level from 8.3% in 1990 to 11% in 2000. 66 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 6-4 Education level Over 15 years o f age (INEGI, 2000) J | 1970 ^ 1990 ^ 2000 Though the improvement in education is clear within the country is clear, there is a huge education gap when compared with the rest of the world, especially the US and Canada, the primary economical partners. Their average education is superior for almost ten years and countries such as Chile and Brazil have an average education of four yeas more than Mexico. 6.1.4 Economy The relationship of education with the quality of life is extremely important. According to an estimate in 1998, 27% of the population live below the poverty line. Consumption capacity and wages have raised slowly, but still remain below 1994 levels. The social structure is composed of a pyramid shape, where the majority of the population lives below the poverty level. There is a sector in the population who have no income ranges between 7.2 to 10.1% (INFONAVIT, 1999). As in any developing country, income distribution is very unequal with 67 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. the top 20% of the income earns accounting for the 55% of the total income, and the bottom 20% earns less than 5%. This foments great social tension and high crime rates. Fig. 6-5 Wealth distribution among the population (IN EG I, 1999) 38.9 P a r c a n g a ta E m p lo y e d (m W o n a) P o p u la ti on w it h /'< 5 Mi n. Sal arl aa Par c a nt a ga - 9 6.5 < 3 5 lin . dalarias 6.1.5 Housing Housing represents one of the fundamental elements for the well being of a nation. It provides individual security and protection for their belongings. The census shows the existence of 21.9 million housing units throughout the country. It is a significant increase of 4.9 million of units in the past 10 years, however there is still a significant need of dwellings. 68 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 6.2 Tijuana, Baja California 6.2.1 Location and Background Fig. 6-5 Map o f Tijuana, Baja California (SDSU, 1994) '•O-* V Baja California State is located, in the heart of one of the most dynamic industrial development regions of the world, in the Northwest portion of the country. From the beginning, the relationship of Tijuana to the US has been contentious. In the late 19t h century Tijuana was flushed with the prosperity of a cattle ranch industry. However the construction of the railroad from Los Angeles to San Diego encouraged the growth of Tijuana with a lot of movement of capital and business ventures. Since then and more so now, the cross-boundary economic interaction has been very visible placing Tijuana in a strategic international trade position (Gilbert, 1989). Another key relationship is that of Baja 69 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. California and the Pacific Rim, which allows fast commercial contact with rest of the world. The limitless possibilities with the rest of the country and the rest of the world are due to the strategic geographical location that this state enjoys. Baja California is the 11m largest state in Mexico with a total area of 27,081 square miles (70.113 square kilometers). It has an extensive coastline of 1,500kilomters, 2 seas and fertile agricultural valleys (Codicorp, 2000). Within this state, the most important city is Tijuana. It’s strategic border location and great economic activity industry, commerce and tourism. Tijuana is the fastest growing city in the country and considered to be the most visited city in the world. Tijuana is located in the border, right next to the city of San Diego, CA. Due to it’s proximity to the United States, especially California, the people of Tijuana have acquired a very unique business attitude that has opened the city's horizons to new and more attractive off-shore ventures. The city has also attracted a great influx of people from all over the country, and the world, giving it a unique cosmopolitan charter. The city's population growth rate is calculated at 3.0% annually. 6.2.2 Population According to the Instituto Nacional de Estadistica, Geografia e Informatica (INEGI) the population growth of Tijuana has been that of 5.8%. Most of this increase is due to the immigration activity of the city. After The State of Mexico (5.4 million) and Mexico City (1.9 million), the state of Baja California has the most number of immigrants in the nation (1.1 million). It is expect that the city Of Tijuana will have a growth of 2 million by the year 2005. This growth has to do with the numerous job opportunities within the city, as well as the proximity to the United States (INEGI, 2000). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 6.2.3 Local Economy The strength of the local economy has to do mainly with the “ maquiladora” industry. This is an industry that offers a number of jobs attracting people from all over the country. Tijuana has an important dollarization economy, which injects over $120 million dollars into the local economy every month, and strengthens the ties to the US. (Codicorp, 1999) This dollarization of the border has allowed lower-middle-class families to purchase their land. This phenomenon is linked only to border real estate markets. According to experts, such as Hiemaux, owning a piece of land has meant not only an increase in land ownership but an acceleration in speculation of land, resulting in higher property turnover rates and ultimately a higher residential mobility rate than in other cities in Mexico (Herzog, 1989). Table 6-3 Breakdown o f economical forces in Tijuana (Herzog, 1989) DOLLARIZED SECTOR Percentage Industry 50% Maquiladora Industry 20% Tourism 20% Residents of Tijuana working legally in the United States 10% Other sources 6.2.4 Border City Driven by the development of export processing zones (Maquiladora), rapid migration to these areas is contributing to the phenomenal growth of peri-urban slums along the Mexico- US border. Population growth in these areas averages 7% annually, and current efforts to meet the basic housing, infrastructure and service needs of the slum dweller have been 7 1 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. woefully inadequate. Housing is precarious, constructed of materials such as old tires, cardboard boxes and wooden shipping pallets, sometimes situated on illegally squatted public or private land, and often in environmentally fragile areas or areas of high geological risk. The problem of housing is compounded by the lack of basic services such as water and sanitation, vehicular and pedestrian circulation and electricity and lighting. In addition, inhabitants of these settlements do not have access to essential community services such as day care centers, commerce for the purchase of basic provisions and open areas for recreation. The lack of community infrastructure and the migratory nature of the slum population have resulted in a lack of social cohesion and corresponding high levels of crime and insecurity. In the past, the Government of Mexico held a permissive attitude toward this rapid urbanization, allowing the uncontrolled growth of the peri-urban areas in order to meet the demand for employment generated by the maquiladoras. However, it is now evident to the municipal governments that uncontrolled growth in these areas is a liability and that it is imperative to establish sustainable solutions to improve the quality of life in the slums of the northern border, and control future growth. Municipal governments in the northern border area have been taking the lead in developing coordinated solutions to the slum problem with the federal government, and in developing partnerships with the private sector. Fig. 6-6 Geographical composition according to Income (Herzog, 1989) > C 2 nrvci m IN COM E C A T E G O R Y H H HIG H T - - ! MEDIUM 72 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The composition of Tijuana is unusual when compared to the rest of the country. The city’s nucleus was located adjacent to both the US border gate and the customs house. The plan of Tijuana did not follow the traditional Spanish grid, with one single plaza. It used a radial design with diagonal streets with a secondary center, very dose to the international border, which was surrounded by the largest duster of residences and commercial activities. 1950 marks a drastic spatial change within the city as a result of the in-migration of predominantly low-income inhabitants, with a growing rate of 11.5%. There is a dear pattern of social stratification within the city. The elite locations are found in neighborhoods close to downtown areas, corridors running along the river, and recently along the coast in the Playas zone. The middle and working dass families are located adjacent to the wealthy zone but farther away from the downtown area. The city poorest is clustered in areas with difficult topography, farthest from the downtown (Herzog, 1989). Currently Tijuana is the most visited border in the world and is widely know as TH E WINDOW OF MEXICO”. Besides it’s the commerce, it has a wide range of entertainment, such as shopping, cultural life, and nightlife. It is the biggest crossing border, with 30million visitors per year from which 25 million cross by vehide to go to the various beaches and camping sites just outside of the city. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Chapter 7 Site Analysis 7.1 Site description The city of Tijuana has very interesting qualities. The unique position gives this city the opportunity to deal with the needs and problems of two countries. The most interesting aspect of Tijuana is not its beauty, but the economic importance, and the immigrants flow density from the rest of the country. Fig. 7-1 Site Plan from West to East ( I ) Playas de Tijuana, (2) Im perial Beach San Diego, (3) Zona Centro, (4) Zona Rio, (5) Garita San Ysidro, (6) Tijuana International Airport, (7) G arita Otay Mesa Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig 7-2 Growth Pattern between 1889-1984 (Gilbert, 1984) The economic importance has favored the growth of distinct zones in the city. One of the most favored areas is the Downtown area, with its tourist quarters, commercial district, and US oriented businesses. Zona Rio (River zone) has a heavy commercial activity, office development and some tourism. (Herzog, 1989) The city lost its pedestrian scale that consisted of three to four kilometer radius. Since 1950 the city transformed into a concentrically expanding metropolis influenced by international migration and economical growth of the northern cities. The history is better explained in Chapter 6. Fig. 7-3 Socioeconomic division by area (Gilbert, 1984) 75 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Clearly chaotic. Tijuana has a clear social stratification within the city. Just as in the rest of Mexican cities, the principal physical segreagation is based on income. Most high class communities are built near the center, along the river and recently along the coast in Playas de Tijuana. Distance from the central business district and social prestige are inversely correlated. As expected, the poor live in fragile topographical areas, at hills, canyons, and flood plains. In some instances, they have managed to occupy some locations where the middle class and the elite have missed to take up, such as some canyons in between middle and elite zones with privilaged locations. One fact is clear, housing covers most of the Tijuana city’s landscape as shown on figure 7-4. The diagram shows an overwhelming dominating factor, that points out the importance of housing in the social picture. Fig. 7-4 Land Use analysis (SDSU, 1994) 76 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 7-5 Residential Housing Quality according to the 1990 Census L ' * t f ,i < v * + o S i* r ' , % ' ' * ) '<a • f v ^ ■ ^ v ^ •- ! ' . * J -.v . A ~ Quality 1 Highest P I Quality 2 Q Quality 3 Q Quality 4 ■ Quality S Quality 6 Lowest The population growth of Tijuana has introduced an immeasurable growth. Over the past twenty years there have been a number of problems that the city was not able to control. In the field of housing, there is a phenomenon of irregular land occupation. This problem is due to two different logics. According to Jorge Alonso one of the main reasons is the big profit that real estate offer, where the focus is directed solely towards monetary gain. The second one is the necessity of poor people to find the only option to occupy a piece of land. (Valenzuela, 1999) 77 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 7.2 Housing Classification The distribution of land for housing is very distinct. It is more striking when seen broken- down color-coded and described in detail. There is a lot of discrepancy when explaining the full spectrum of quality availability. 1. Housing quality 1 belongs to the elite residential homes. The dwellings are architecturally designed expansive luxury homes with the full compliment of infrastructure and services. The structures enjoy a standard fabricated construction and a variety of materials selections. 2. Housing quality 2 belongs to the Upper Middle-lncome Residential homes. The size and materials are less elaborate than houses in class one. but they have a complete disposition of infrastructure and services. 3. Housing quality 3 belongs to the Middle-lncome Residential homes. Typically homes in this class have access to all services, however not all roads in these areas are paved. These homes are almost fully accreted in terms of construction. The use of less conventional materials is evident. Some Government housing is included in this class. 4. Housing quality 4 fit in Lower Middle-lncome Residential homes. This level of housing is rapidly accredited and has dynamic process when constructed. In terms of materials, a wide range of materials is employed in improving the houses. The presence of paved streets, electricity, water, and sewerage is evident but irregular. 5. Housing quality 5 defines Low-lncome Residential homes. This level of housing is constantly being transformed into stable structures, commonly represented by the replacement of wood with cement block. Dirt roads, pirated electricity, trucked water, and privies are common. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 6. Housing quality 6 belongs to the Squatter Settlements. They are usually located on the periphery of cities. Dwellings in this class are typically built with scrap materials such as metal, wood, cardboard, and plastic. These recently settled areas lack formal services and infrastructure and represent the most impoverished housing quality. Squatter Settlements are located in irregular lands and are in the most fragile ecosystems where nobody wants to live. The lowest strata of the population cover the biggest area in the city. The site that I have selected for this thesis is located in an area called Los Laureles. 7.3 Site Location This site is located in a canyon right next to the US border separated by a metal wall. This is a very low-income ‘ colonia’ or neighborhood. The fastest way to reach this neighborhood is through an almost invisible exit in the freeway towards Playas de Tijuana, an Upper middle high-income neighborhood right next to the beach. Los Laureles has very pronounced slopes, ranging from 25 to 35 degrees. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 7-6 Slopes, Faults and Hazardous Terrain 100 fear Flood Way SUodobwm bcJaam do 100 A*o> 100 fear Flood PWn This site is surrounded by a number of geological faults. Figure 7-7 shows the faults represented in black lines. There are three faults located from north to south on the West, in adjacent canyons. Crossing the International border to the north there are a number of faults that are located very close to the Tijuana river Valley and some on the North East of Los Laureles, very close to the International Wastewater Treatment Plant in the US territory. The vegetation in this area is coastal sage scrub, some Chaparral, and the rest of the land has been already developed. According to the San Diego State University 1994 sources and methods Manual most of the land has been already developed (San Diego State University, 1999). 80 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 7-7 Geological Faults close to the Los Laureles Site in the US and Tijuana. e Laureles Fig. 7-8 Vegetation in Los Laureles □ D evel o ped Zonas U r ba ni zad as O pen W a t e r C u erposd e A gua D i st u rb e d H a b i t a t H l b U a i s F e r t urbad os C o a st a l Sage S crub M a te ri a l C o st e ro M a ri t i m e S u c c u l e n t S cru b M a l o n a i S u c u l e n l o M a ri ti m o C h a p a rra l C h a p a rra l Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 7.4 Specifics 7.4.1 Figure Ground The site is located in the 'Colonia ’ Los Laureles know as the Goat Canyon. This is a small 4.6 square mile sub-watershed of the larger Tijuana River Watershed. It is located 1 to 2 miles form the coast and 90% of the watershed lies in Mexico. This is the site for the sub basin because it flows directly into the Tijuana River National Estuarine Research Reserve (TRNERR). It is a significant source of sediment in the south end of the stream. (Roper, 1998-9) Over time this area has become completely developed and degraded. The decay in the area has to do with the squatter settlements on the steep hillside in the Mexican side of the border, while on the US side border patrol roads Kris-cross the area. These are the main factors among other that have contributed in the disproportionate erosion and sediment loads in the canyon. Fig. 7-9 Solid and Void Diagram o f Los Laureles m LOS LAURELES 1 E j S i l U 82 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 7-10 View o f the Canyon, Los Laureles 20001 Fig. 7-11 Decay and Erosion Caused by unplanned settlement, 2001 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The lack of a sensible master plan of this area has not only deteriorated the landscape of this area but has limited the public access to Border Filed State and contributed to the serious salt marsh habitat loss. It is time to create a sensible master plan where nature and humans can co habitat in harmony. There is room to restore the salt marsh, and make this Canyon safer for the people. There is a lot of work to be done, starting with the education of the people regarding safe living and create an erosion control in the Mexico side by creating basins and re-planting the natural habitat. 7.4.2 Zoning Fig. 7-12 Los Laureles Zoning. SECCI ON TECNWEX Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Most of the land surrounding the site is highly urbanized. The yellow represents the squatting homes that surround the area. The rest of the land is completely open, with some roads passing by. This is one of the accesses to the beach area. There is a water source in the foot of the site. This water area is canalized flowing in between the main streets by a concrete structure, where the black water flows through. All the houses are composed of one story high, in very few cases there are two stories in height. Fig. 7-13 Transportation and Access to Los Laureles 3 I 3 1 1 *: SECCION TECNOtiEX 7.4.3 Access The access to this area is difficult and limited. There is a clear distinction between the primary and secondary access. The streets are wider, and even though they are not paved, they are more defined by heavier usage. There is one main access from the highway, the 85 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. other access goes through another poor neighborhood from Playas de Tijuana, and is difficult to reach the “Los Laureles” area. The streets are poorly constructed and are not paved. The steep slope does not help this situation, especially in rainy seasons. The international border lies parallel to the Highway, and is heavily patrolled, while in the Mexican side it is always busy with eager people who want to cross to the other side. The majority of the people, whose dreams were in crossing the border, remain in the Mexican side. 7.5 The Site The site is completely empty and is located in a very steep slope. The surrounding area is heavily urbanized with single story buildings. From far away, this area looks as a carpet with different textures and colors that create a feeling texture almost alien to the site due to its ever-changing topography. Fig. 7-14 Los Laureles Canyon Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 7-15 Los Laureles Canyon SECCION TECNOKEX Reproduced with permission of the copyright owner. Further reproduction prohibited without permission Chapter 8 8.1 Principal Mission The main purpose of this study is to understand the relationship between the man made and the natural environment. It is possible for buildings to coexist without disharmony; building on hillsides is possible without brutalizing the environment, and with minimal danger for people. In the past decades we have seen many changes in the world. These changes have been good and bad. However, one of the principal problems to be aware of is the immeasurable growth in cities around the world. As mentioned before, some cities such as Sao Paolo, Brazil and Mexico City have more than 18 million people and there is great demand of space, especially a place to live in. Theses basic needs are not extraordinary, however, the demand has surpassed the capacity of supply, and in many instances is beyond the power of the governmental institutions in charge to fulfill these needs. The living conditions of many are precarious bellow human needs and these situations have to change. There are numerous problems that need to be solved. The one in this study is similar to others located in the periphery of any metropolis. This study includes the analysis of the hillside conditions that are already heavily populated, and where the basic infrastructure does not reach. It is possible to reach a solution suitable for any human being. The aim of this study is to propose well planned hillside housing, specifically terrace housing as a viable solution for low-income housing. The objective is to adapt the building to tha ground and not the ground to tho building, for improved performance in earthquakes; using an existing site in Los Laureles, Tijuana, Mexico. The study is based in a system of structural modules that are related to the angle of the slope. The building hardly breaks into the ground, and when it does, the retaining wall is very small, 88 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. using the alternate methods explained in chapter 3 to avoid erosion. Using these basic principals, together with sensitive human scale that terrace housing offers is the beginning of improvement in the quality of housing to offer a solution for the alarming need for affordable housing in developing countries. It is important to clarify that terrace housing is not less expensive than buildings on flat sites but flat sites are not available at affordable prices. 8.2 Current Practices Chapter 1 explains the current techniques in more detail, yet it is important to reiterate the current practice on sloping sites to avoid future mistakes. Currently the common solutions have been the adaptation of he site by the cut-and-fill technique. This is a costly method that involves a series of possible sliding surfaces, and generally it involves the removal of great quantities of soil to achieve the desired flatness. There is great danger in provoking landslide in the process of cutting, if it is not cut at a safe angle and properly compacted. Steep cuts are a common practice in countries such as Hong Kong. These slopes can remain stable for many years. However it isn’t unusual for these slopes to fail in earthquakes and after heavy rain as the rainwater saturates the soil, reducing the suction infiltration capacity and causing the soil to break away. This is usually common in areas such as the side of the streets and highways. The removal of the vegetation causes an unbalance in the stability of the ground. A more detailed discussion can be found in chapter 3. Slides in filled areas is one of the most common reasons in filled areas, especially if a building is located half in the cut and half in the fill section. There should be a balance between the cut and the fill areas. However most of the time this solution is not possible as the material excavated from the cutting may not be compatible nor suitable for the fill area, or with time both of these terrain settle at different 89 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. rates. The other major problem is that the fill is not sufficiently compact. This becomes a problem, because the loose material may slide and settle unevenly due to variable depth. Compacting the soil could be a solution, however any small change in the composition of the filled area, could cause a slide, which is extremely dangerous, due to the little warning it offers, and the speed and long distance soil is capable of travelling. (Abbott, 1989; 254) Studies show the instability of buildings in cut-and-fill land. Even well compacted fills may experience long-term settlements due to differential depth and secondary strains or hydro- compression. In many cases due to varying fill material thickness great impact could occur in residential structures on the site. When it comes to damage, differential settlement is a more serious threat to the integrity of the structure than total settlement, and what is more dangerous is that it is very difficult to detect. There is a lot of danger in cut and fill construction. According to Vergun: "The main conclusion drawn from this case study is the extreme vulnerability of houses built on cut and fill sites to settlement of fill during earthquakes. No amount of superstructure strength could have prevented damage to it when one third of the foundation settles and rotates down slope." (Schierie, 2001) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 8.3 Matrix Fig.8-J Ground access to every unit Studies show the clear dangers of current solutions. In order to avoid tragedies of natural phenomena, such as earthquakes and mudslides, it is crucial to study and read nature. If everyone worked with nature instead of against, buildings would be safer. Every earthquake, every landslide has taught us different lessons to improve the built environment. It is imperative to find balanced solutions. A key solution would be for the building to adapt to the site and not the site to the building. It is time to realize that progress is not always better. Our ancestors were very careful in reading nature and work with it. The Mayans were masters in site planning and grading. The great Italian Hill towns molded to the site, and not the other way around. Even in the 20s the early architects used the site as a challenge. This study is an attempt to study possibilities in crating a module that fits the ground according to the site slope. These modular configurations adapt to the slope of the site; configured according to the height and depth of desired living spaces; starting with minimum dimension. The minimal dimensions were 7 feet in height by 1 1 feet in depth; progressively increased to a maximum height of 12 feet and maximum 12 feet depth. 91 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 8-2 Continuous Structural Flow Once the dimensions were set, the ground line was drawn connecting the comer closest to the ground to each other. The resulting matrix system allows the visualization of all the possible combinations. The key to this system is the perfect alignment of the structure, without any deviation to transfer the loads. Using this matrix it is possible to determine the dimensions of the basic structural modules. See appendix I. Table 8-1. Module Dimensions (feet) and related site slope (degrees) 32.5 30.3 28.3 26.6 24.3 23.6 22.4 36.0 33.7 31.6 29.7 28.1 26.5 25.2 39.3 36.9 34.7 32.7 31.0 29.4 27.9 42.3 39.8 37.6 35.6 33.7 32.0 30.5 45.0 42.5 40.2 38.2 36.3 34.5 32.9 47.5 45.0 42.7 40.6 38.7 36.9 35.2 92 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The idea is to adapt the building to the site, almost as floating. Structural walls line up from top to bottom all the way to the foundation. Sometimes, if the structure does not match the slope completely, one of two things could happen. The structural column could extend down to the ground, then some units may not touch the ground completely. This condition can be used to provide to allow cross ventilation. The matrix shows all the possible combinations of dimension according to the angle of slope. This method is a way to systemize the process of adapting to slope. It allows seeing the basic diagram of a building in a sloping site. The importance of having a systematic chart to consult the composition of the ground where a project will be erected simplifies the construction process, by making it safer. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Chapter 9 Structures 9.1 Introduction Structures are the man made way of assimilating to natural environment. With ingenuity humans have been able to protect themselves from the natural elements ensuring their survival. This instinct is mixed with the ability to of creation. According to Agustin Hernandez, “ structures is the principal where intuition and knowledge is fused into a rationalistic process..." he further adds “ the process of design there is only one law in the creation of new realities, architecture(A. Hernandez, p. 50, 1998) Without the structural elements, it is impossible for the design to take shape, as it would not stand up. Nature has the ability to create perfection. We see hundreds of elements around us, amazing for the careful observer. There is a realization of a sudden perfection of balance that all the elements create when put together, and a realization of importance that every individual element has. In the process of analyzing the concept of beauty in the design of a building, many lessons can be taken from the perfection of nature. Form, Site, and Structure cannot exist without each other. Should any of these elements not be present, the building, no matter how simple or complex will perish. Sloping sites are especially complex. A careful understanding of nature is greatly needed in order to understand the relationship of the object with the site. The simple analogy of a tree helps to visualize the intricacy of relationships. A tree is an external element in the landscape, which causes a dynamic interaction at the touching point with the ground. The roots of the tree stabilize the ground, and keep the tree and the ground steady, in complete balance. This relationship is pure. We should seek solutions that will achieve this balance with our environment. This balance could be achieved only if there is respect of the built environment in relationship with the natural environment. The study will explore the importance for the building adapted to shape 94 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. to the ground and not the ground to the building. The study of adaptation described in chapter 5 will be further enhanced with the foundation design, which is the immediate relationship of the ground with the building. Furthermore the materials used create interesting construction solutions in relation to the availability of materials, the social acceptance to the type of material, the cost, and the technical aspects of construction. The materials considered are wood and concrete. 9.2 Foundation 9.2.1 Methods to adapt buildings to the site and not the site to the building The foundation keeps the building tied to the ground. This relationship between the ground and the building is very strong. It is the connection that the man made has to the soil. This connection has to be sensitive to the ground. The foundation carries the weight of the structure therefore it has the same role as the roots to the tree in the natural environment, which keeps the building steadily, grounded. The structure takes a tree-like form, with a concrete trunk, and steel with concrete roots. Foliage is composed of concrete frame and masonry, or wood, depending on the variation. The key element is the soil. As described in Fig. 9-1 H ard Soil, no water absorbency. Tijuana 2001 95 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. previous chapters, the Los Laureles area has a particular soil composition. The water hardly soaks into the ground, and during rainy seasons a lot of the external elements wash down. This is a hard soil to handle it is mostly composed of clay. Due to the fragility of this soil it is necessary to treat it with great care. The most important thing is to adapt the building to the ground and maintain cut and fill to the minimum. The footing should be deep and wide enough without disturbing the whole ground in general, ensuring minimal disturbance of the ground. 9.2.2 Sample study The structure is composed of modules, which minimize complications for the structural unit. Once a pair of units is built, the same technique can be used throughout the rest of the units. Sample study (A) has a structural module of 14’ deep by 24’ wide. The slope of the site is 34 degrees, and the structural walls are aligned straight all the way down. The key element is to respect the ground and avoid erosion, and maintain the balance to the environment. 9.2.2 Foundation To minimize soil disturbance caisson foundation are used. This footing consists of a cylindrical shaft, which is hand-dug into the ground and then filled with concrete to create caissons to support the loads of the building. To size the caisson foundation, there is a need to determine the load of the structure and substructure (See calculation in section 9.3.6). When using masonry structure it is recommended to use strip foundation. 9.2.3 Beam Wall The rear bearing walls act as a beam supported by caisson foundations. The wails transfer the weight of the structure in an even way to the caissons. The linear elements that compose the structure allow a direct transfer of the load. The wall acts like a very deep beam, which also provides lateral stability. This system respects the natural environment by minimizing 96 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. the intrusion on the ground assimilating the trunk of a tree. This system provides lateral stability and strength. The caisson foundation takes minimal surface area, allowing the natural elements to take the natural course. In heavy rainy season the water is not blocked by the continuous foundation, reducing the risk of a wash down of the building during rainy season. This also reduces the risk of major cracks of the structure. Fig. 9-2 Beam Wall with even Cantilever / / / / f / / 6’ > 18’ / 18’ > 6’ 9.3 Construction Materials 9.3.1 Wood Wood construction is one of the most widely used materials in the US for residential constructions. However this choice of material is not popular among most of the rest of the world where their choice of material is concrete, brick or concrete block. However timber- frame buildings, if properly built, have not an inferior quality. There are a number of 200 year old buildings in New England that are still in good conditions. The advantage of wood- frame construction is that it is a renewable material, and can be built where wood is available. (Anderson, 2000) The availability of material is extremely important. Considering earthquake resistance, wood has great advantages: light weight and resilience. The small 97 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. weight is of great importance since earthquake forces are proportional to mass. Since seismic forces are based on Newton’s law force equals mass times acceleration (f=ma), the resilience of wood is also a positive factor to resist earthquakes. 9.3.2 Advantages of Wood Timber has a good performance under earthquake conditions, due to its lightweight and high strength to the weight ratio. Timber lacks the inelastic behavior of steel. Another advantage of good thing about wood structures is that it has little degradation of strength or stiffness under cyclic loading and has good damping properties. During an earthquake, the performance of the movement is directly proportional with the weight of the structure. Due to the lightness of the wood structure, there is less danger of causing major catastrophic results, as history proves it. 9.3.3 Shear panel construction Shear walls and floor and roof diaphragms determine the strength and stiffness of timber construction. They are composed of wood frame with plywood nailed to the wood and metal connectors to attach walls to the caissons. The relationship of the area to the overall size and shape to the panel and the position and openings within this element such as windows and doors determine the strength of the walls. Another element that determines the strength of the structure is the quality of the frame structure and the connection elements to the diagonal or sheeting elements to the frame. In the Northridge earthquake one of the major failures was the lack of consistency in the nailing of plywood to the framing. The connection between timber members is extremely important. This connection involves the use of glue, nails, screws, bolts, metal straps, metal plates or toothed metal connectors. According to Evans, under earthquake stress he recommends the use of metal comer plates or toothed steel connectors. This ensures more strength under this kind of pressure. (Dowrick, 1989, 283) For nailed joints, nail size and spacing are most important. A nail 98 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. driven parallel to the timber grain has less than two thirds the lateral load resistance allowed for the same size nail normal to grain. Diaphragms should have a perimeter framing that resist the longitudinal forces caused by seismic loading. One of the key elements to prevent failure in buildings is the connection between shear walls and foundation or between successive stories. After the Northridge earthquake it was found that these connections were often not carefully placed, and a lot of the damage took place due to poor installation of these connections. Connections of shear walls must be capable of transmitting the horizontal shear forces and the overturning moments applied to them. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 9.4 Calculations W = 1500psf 9.C X) . 1 9 nor . i*nm A = Tributary Area A = 24' x 14' x 3 stories A s 1,008 sq. ft Reduction Factor R s 0.08 (A-150) not to exceed 60% R = 0.08 (1008-150) = 69% R*60% LL= 40 psf x (100-60%) LL = 16 Psf DL * 20 Pef I = 36 Psf w = 3 (36 x 14) Reactions Rb= 1.500 x 2 4 'x 12 18' Rd= 1.500 x 2 4 'x 12 18' R c = 1.500 x 48’ - 2(24,000) Iv = -1.500 x 48' + 3(24,000) Shear Va = 0 Vw. = 0 -1 5 0 0 x 6' VbR = • 9000 + 24,000 VcL = 15,000-1,500x18’ VcR = - 12,000 + 24,000 x 18' VdL = 12,000-1,500x18’ VdR = -15,000 + 24,000 V« =9,000-15,000 x 6’ Shear Flow Mmax * Vma» h M m ax = 15.000 2x9’ LL = 26psf w = 1.5 klf Rb = 24,000 # Rd = 24,000 # Rc= 24,000# Iv = 0 OK Va = 0 Vw. = -9 ,0 0 0 # V m i * 1 5 , 0 0 0 # VcL * -1 2 ,0 0 0 # V cr * 1 2 ,0 0 0 # VdL * - 1 5 , 0 0 0 # VdR * 9 ,0 0 0 # V d R *0 OK M m a x * 833 833 <870 OK 100 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3.5* E 9.25" X _ = 54 in 2 Fig. 8.5 Wall Section Parallel Axis Theorem Moment of Inertia loo s bd 12 = 3.5 (9.25V* 12 Y « 9* X 12" - 9.25 Ixx s £ (loo ♦ Ay*) a 2 x 231 + 2(3.5 x 9.25) x 49.42 Section Modulus loo a 231 in4 Y a 49.4 in Ixx a 158,475 in4 s- l c a 158.475 54 Bending Moment Mb a V b l x 6' 2 a - 9.000 x 6 X a VbR W X a 15.000 1,500 2 Mx a . 9.00Q + 15.000 X 10* 2 Bending Stress fb» m S = 66.000 #’ x 12 2,934 49.4*49.4*9.258 S a 2,934 in3 Mb =-27,000#’ X a 10* M. a 66,000 #’ fb a 270 psi 270 < 1,200 psi OK 101 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 9.5 Case study A Fig. 9-3 Site Plan and Site Section O o t b . 102 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Case study A has a slope of 34 degrees. Using the matrix, it was determined the dimensions of the modules to be 14feet by 9 feet (deep by height). The structure adapts to the ground. In this case there is no cut to the ground. Only the foundations penetrate the ground. The upper two units float above the ground. The access is accomplished through three to four steps. The site plan is determined by the natural conditions of the site, and not by a geometric grid. This gives the community to grow according to their community needs in an organic way. It is important to allow the units to be placed according to the slope of the site. Figure 9.3 shows a sample of the possible solutions for this community. The structure needs to be placed perpendicular to the slope to ensure the best performance according to the matrix formula. Fig. 9-4 Cross Section 103 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 9.5.1 Section Fig. 9-5 Side Elevation with Unit Plans ^ - ■ ' 1 1 = 4 i ■ i 3 0 ’ 5 ‘ 1* 15’ 5 0 ‘ The section shows the composition of the modules in a clear way. The structure is linear, simplifying the structural load throughout the building. There is a maximum of three units on top of each other. The caisson foundation has a maximum depth of four feet. They are tied together with a strip frame as a security device. The structural composition allows complete 104 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. privacy from unit to unit. Conceptually it is easy to oversee the neighbor below, however by placing a planter and a pergola, it is impossible to see the neighboring terraces. 9.5.2 Units Fig. 9-6 Typical Floor Plan I , t _ C l r f A j I D a I qii —p i II jjrr | K S l E 1 1 ---- --------------, n n SG i — i j u , 1 □ □ ' □ ^ o 1 D 2 o J 3 l! 1 — ! i : ^ ' 1 1 £_____ J □ • . I ! sm nrnim m * * * S ! Each unit is composed of three modules, when counting the terrace and two without counting the exterior space. The interior space has an open plan kitchen, dining and living room. This is to maximize the interior space. The square footage is: Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. One module area A = 14ft x 24ft Interior space area A = 336 ft2 + 336 ft2 Including terrace A = 336 ft2 x 3 A = 336 ft2 A = 627 ft2 A = 1,008 ft2 Every space has an opening such as a door and a window except the bathroom. This ensures cross ventilation. Cross ventilation is defined when there are two openings opposite to one another or in adjacent walls (when perpendicular). The same structure that supports the floor directly above the caisson foundations supports the structure of the balconies. The balconies have a width of four feet each. That means that the beam cantilevers six feet plus four feet of the balcony. Figure 9-7 highlights the idea of this structural frame. The thick lines represent the beams. The broken lines represent the joists. They are placed 16 in on center. The harmony of the structure has a lot to do with understanding the physical characteristics of a sloping site. Fig. 9-7 Structural Diagram o f two consecutive units. 106 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 9.6 Detail The wood frame has some particular details that make this structure efficient. The most important detail lies on the wall detail. The perfect alignments of the wall elements make this detail interesting. The wall that divides the two units is actually composed of two with a Y* inch gap. This ensures very good acoustics. The gap guarantees the sound t stop. Fig. 9-8 Typical Wall D etail While this solutions seems acoustically sharp, structurally is a disaster, because there is no continuation for the gravity force to flow down. However, by placing continuous plywood on 107 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. both columns, it ensures the transfer of shear to the member below instead of the sound transfer. Structural elements provide the strength to the building. The logic of this structure allows better performance should an earthquake occur. Building on sloping sites is not the most economical, however the safety of the inhabitants should be placed as the number one priority. This system has integrity to respect the ground. The outcome is a structure that is safe and beautiful. Fig. 9-9 Wall detail with continuous plywood to transfer shear 108 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Chapter 10 10.1 Environmental Control Introduction The sun is the most important source of energy in our lives. Throughout time, every culture has learned to work with it as the seasons of the year pass. The sun has been the element that orients us and gives meaning to the every day chores. The Mexican ancestors were aware of the sun’s power. Their knowledge was so great, that the calendar revolved around it.1 Their belief in the sun’s power to destroy, and to heal, led them to respect the sun completely. With time we have learned to work with the sun day by day, season by season, year by year. According to Ralph Knowles, “ rhythm is the way our bodies and emotions respond to the passage of time. It is therefore a universal means of affecting experience, and conveying meaning in our lives’ (Knowles, p.1). In the "modem era” , we have forgotten or choose to ignore the lessons that our ancestors have taught us. We build multi-story boxes, without any notion of orientation, which provide the user with no sense of direction, geographic location or space. These boxes are 'ubiquitous' and look the same all over the world. We ignore the natural warmth of the sun during the winter and the harsh summer sun when initially designing the building. Therefore we waste enormous amounts of energy in heating and cooling the building when this can be done using the natural resources that are 1 The Aztecs, like the Mayans, believed that the universe had been created five times and destroyed four times; each o f these five eras was called a Sun. The first age was called Four Ocelot (for it began on the date called Four Ocelot). Tezcatlipoca (Smoking M irror) dominated the universe and eventually became the sun disk. The world was destroyed by jaguars. The second age was Four Wind, dominated by Quetzalcoatl (Sovereign Plumed Serpent); men were turned to monkeys and the world was destroyed by hurricanes and tempests. The third age was Four Rain, dominated by Tlaloc (the rain god); the world was destroyed by a rain o f fire. The fourth era was Four Water and was dominated by Chalchihuitlicue (Woman with the Turquoise Skirt); the world was destroyed by a flood. The fifth era, the one we live in now, is Four Earthquake, and is dominated by Tonatiuh, the Sun-God. This age w ill end in earthquakes. Hooker, Richard; Culture in America, http://www.wsu.edu/--dee/CIVAMRCA/AZTECS.HTM 109 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. already available to us. Although mechanical systems have given the designer a great deal of flexibility, they have resulted in a trap without the ability to adapt: boxes, which are totally unresponsive to the environment. Innumerable examples of this deliberate unresponsiveness are seen all over the world in major cities. 10.2 Advantage of Slope Sites A sloping site provides a variety of shades of solar passage. There are many advantages as well as challenges when dealing with the solar access in sloping sites. The solar access boundaries go beyond the immediate site; they include the adjacent buildings, as well as the actual slope that the building rests on. The angle and orientation of the site are the two major elements that influence the building’s access to the sun. The key to good solar design is to integrate the building with the natural environment and not treat it in a vacuum. Just as in the structure of terrace housing, where the building respects the ground by adapting the structure to the site and not the site to the structure, we should respect the access of the individual units to the natural energy of the sun. The orientation of the slope plays a key role. When the slope faces south, it does not obstruct solar access to the building. When the slope is oriented to the north, the ground determines a lot of the boundaries by creating new limits and new patterns in the ground and in the building. With an understanding of orientation, buildings should not look the same, even when mass-produced. Natural light unlocks infinite possibilities in the creation of space. It is necessary to create space not because it looks “ cool" but because its design arises from an inherent understanding of the function of the space to create transitional morning and evening spaces, which are sensitive to the time of day and the use within the space. HO Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 10-1 Shadow cast in a north-South oriented slope (Knowles, 1981) S N The understanding of the natural elements seems trivial, yet not many truly understand it. In many cases it is worsened by the lack of sensitivity towards the local climate, creating senseless spaces with heavy usage of air conditioning. Orientation plays a major part in the shape and amount of solar passage a specific project receives. Most of the cities have monotonous buildings that look the same when facing north south, east west, or any variation to this. In Los Angeles, for example, the city grid plays a major role, and most of the buildings conform to these man made boundaries. Buildings in the north south orientation should not be conceived the same as buildings on the east west orientation. The major difference lies that the south fagade has the most sun access, and as the time of the day progresses, the buildings cast a specific shadow to the neighbor buildings, sometimes casting shadows the whole day. A well designed, sensitive space can provide the user with a sense of identity and subtle connection to nature. This space ensures a comfortable space in every season of the year during the whole day. It is crucial to go back in time, prior to the air conditioning era, and understand the principals of the vernacular buildings, which knowledge has been passed from generation to generation, and avoid the mistakes of unsuitable buildings for the local climate. Sloping sites are very complicated to design, because there is an additional element that is crucial for the structural erection as well as the ability to control the quality of life, it is the ground, and how it reacts with the project in the particular location. When building on 111 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. sloping sites, the dwellings can be built close to the ground, this ensures every unit the closeness to the ground, and at the same time enjoy equal access to natural lighting, if the slope is continuous with no abrupt change. Terrace housing, as mentioned above, has an efficient structural solution. In addition terrace housing provides external flexible space to use according to the needs of the seasons, social and practical needs of the inhabitants. The terrace serves the needs of two different seasons, summer and winter. The angle of the sun in the summer is higher than in the winter, providing a higher solar envelope area. The aim of this study is to understand the environmental needs of the basic low-income unit using low technological solutions to achieve a good comfort level throughout the day and the year. 10.3 Definition of Solar Envelope There are two main components that are essential when dealing with the sun in relationship with the body. These are: • Human comfort • Choice of quality of life. The human comfort deals with measurable devices that impact the human body directly in the form of convection, evaporation/respiration, and radiation. When dealing with the sun and human comfort level there are two components affecting this relationship: thermal and luminous access. Thermal access usually is the association of radiant temperature which refers to the average temperature felt as a result of radiating energy from a surface of a room combined with the room air temperature to produce a comfort level to the human body. Here the higher mean radiant temperature grant comforts at lower air temperature. In the 112 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. following chart suggests 70 degree F as the common comfort perception (Anderson, 19: 1994). Table 10-1 Mean Temperatures Mean radiant temperature: 55 85 80 75 70 65 60 Air temperature: 91 49 56 64 70 77 84 Luminous access deals with the access to natural lighting of an individual unit as well as the access of the sun’s path which define the amount of shadows that the building casts on itself and its surroundings. The solar envelope is The largest theoretical volume that can be constructed on a site without casting harmful shadows on adjacent properties'' (Knowles, 1981). Under this theory there is no shadow casting the neighboring properties, and every dwelling enjoy direct and equal solar access. The duration of this access is defined on the number of hours in dependence to the use in accordance to the energy purpose and in relationship to the technological understanding. The most practical period of time terms of reception is that of six hours per day throughout the year. This number in isolation does not mean anything because the sun’s energy is not equally distributed throughout the day or the year. The sun hits the ground, or in this case any project parallel to the ground during the sunrise and sunset. During this time, the rays of the sun are very low and tangent to the surface of the earth providing minimal energy access. At noon the altitude of the sun is the highest of the day, with the maximum sun energy access of the day. The same principal occurs throughout the year. Figure 10-2 shows the path of the sun throughout the summer, the equinox and the winter. During the winter the sun has the lowest angle. As an example, 1 13 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. the angle of the sun in Los Angeles at 9 am in the summer is greater than in the winter, therefore the energy of the sun in the winter is less than in the summer. In the winter at noon the sun energy is (sin 31.5 deg. = 0.52) only 52% as compared to the sun energy in the summer at noon, (sin 78.5 deg. = 0.98) which is almost 100% (Knowles, 58; 1981). Fig. 10-2 Sun path during the three seasons o f the year (Knowles, 1981) SUMMER WINTER The sun rises to the north of east and travels to the highest altitude angle of the year and sets to the north of west. In the winter, sunrise takes place to the south of east, travels to the lowest altitude angle of the year at noon, and sets to the south of west. It is only during the equinoxes in the fall and spring that the sun rises exactly due east, the angle of the sun at noon is lower than in the summer and higher than in winter, and sets exactly due west (Knowles, p. 53). It is clear that the sun path is predictable according to latitude, altitude and the geographical location. This information is widely published and available to the public, therefore there is no excuse not to taking full advantage the sun’s natural benefits. 10.4 Solar Envelope Parameters The definition of the solar envelope has to do with the future possibilities in taking advantage of the energy resources to the fullest. A good practice is to assure solar access to one's 114 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. own building as well as the neighbors and the surrounding landscape. These considerations will ensure a “ good neighbor” policy, which allows a dose relationship to each other. The Solar envelope is the largest volume on a site that does not cast shadows on surrounding properties during a defined period of time (Knowles, 1981). The envelope can be created in urban and rural areas and should not be treated the same. The designer and the planner have the responsibility to define an intelligent outline for the rural area, and important guidelines for the improvement in the urban areas. Zoning ordinances already exist, what the solar envelope does is help define these height by defining the solar-access during the critical times of the day. Instead of the height to be completely arbitrary, the solar envelope would help in the decision process of height and shape of the ‘largest possible building mass”. (Kensek, 1997) The current buildings should relate to the older buildings which in turn will be closely inter linked with the future buildings. This ensures equal solar access for everyone assuring sunlight for everyone. The synergy of the built environment with the natural environment should take place by feeding from each other. The solar access gives the inhabitants of the units possibilities in taking advantage of the most productive hours of the sun during the day and the time of the year. There are many aspects and conditions that affect the boundary of a site and affect the size and shape of the solar envelope. These activities could range from drying clothes on the terraces, growing vegetables on the units. These activities correspond to the movement of the sun, enriching the life of the inhabitants and discouraging monotony. In addition, the solar envelope encourages the usage of free solar energy. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 10.4.2 Hillside Fig. 10-3 Site Plan Mass Model The slope of the site affects the design of the solar envelope. The slope creates slanted surfaces and creates different elevations. Depending on the orientation of the site, the shadows of the slope are shortened or elongated downward establishing new parameters of solar fences and boundaries. The steeper the slope, the higher the parameters of the solar envelope. The height of the solar envelope diminishes as the slope reaches horizontal position or vertical position. In terrace housing, the solar envelope has very restricted parameters, yet it posses interesting solutions. The first step is to determine the privacy fences and set the solar boundaries in the site and the project. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 10-4 Site Plan Case Study A In Case Study A each unit has full access to the sun for a period of six hours throughout the day and throughout the whole year. As already established the cut off time starts at 9 AM until 3 PM. This ensures each unit to maximum solar access. Each unit is provided with a privacy fence that ensures full solar access to each individual unit. The fence boundaries are located within the unit ensuring full solar access for a period of six hours. The envelope fence has a height of 8 feet for every unit. 117 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 10.5 Case Study Fig. 10-5 winter. Composite, summer envelope Fig. 10-6 Composite Envelope determines the total height The envelope is generated for the winter, summer and equinoxes, and then the result is the composite envelope, which combines the summer and winter maximum solar capacity. This allows the creation of one single fence to fulfill the necessities of the whole year. The project was generated with Cs Solar, a program designed by Professor Karen Kensek in conjuncture with Professor R. Knowles, in 1997. This program is a modified version of the SolVelope a computer program that calculates the solar envelope through a series of inputs, as the generating tool. (Yeh & Schiler, 1993). The user enters the necessary data regarding the project. This is a program that is loaded to Autocad 14 or 2000. This is very useful because it can be integrated with the drawings that are already generated in the program. The information need to generate the envelope is the size of the land parcel, the boundary 1 18 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 10-7 Overall View from the front condition for shadow casting, and the latitude of the location as well as the desired periods of the solar access and angle of the building. Once this date is entered, the program calculates the desired solar envelope for the winter seasons, the summer seasons, the equinoxes and a composite envelope. For the terrace housing it was decided to keep the simple structural system, to ensure efficiency and safety should a natural disaster hit. Then, the usage of the solar envelope was emphasized on the terraces. With the passage of time, these terraces will acquire its own character according to the needs of the residents. The terraces take an important role in the life of the resident. Every frame is set according to the maximum limit of the solar envelope. The maximum height is reached in the summer. The dynamic possibilities are present. They have to be combined with the social composition. Every day activities become part of the cycle of life, until they become habits and transformed into rituals. The pergola is an element that will change as season's change. Hanging out the clothes become into a recreation area, for Mexicans are found of social activities. Above all, this is a private area that ensures privacy in very comfortable way. 119 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 10-8 East Elevation with the Pergola Outline 10.6 Environmental Control Fig. 10-9 Canvas o r 'Toldo" as shading device Individual building elements can control the access of the natural light to the interior of the individual dwellings. When designed with care and understanding of the natural elements, 120 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. the building has the capacity to make evident a sense of the change in the seasons. A dwelling should showcase the changes without the loss of the comfort zone. Housing on temperate climates, such as Los Angeles and Tijuana are able to achieve a comfortable living environment throughout the year, without the need of mechanical systems such as heating and cooling. Low-income housing does not mean poor design, and inefficient energy. However, low income housing have suffered the most in quality of materials, space, and living conditions. It is important to consider the day to day experiences and design for the best result throughout the year. In addition to the understanding that the natural light is the source of energy, there are three basic elements in the heat-transfer processes that need to be understood: Conduction, convection, and radiation. They determine the energy that is transferred inside a building. The insulation capacity of any material is know and well recorded in books. It is therefore crucial to take the information, study the type of material used and see how to improve the performance of these materials. The most common materials used in Mexico are concrete block and brick, which are very poor in insulation. This study focuses on: ♦ The internal shadows and the movement of the sun ♦ The Conduction performance of the existing wall material ♦ The Conduction performance with the addition of insulation The technical knowledge acquired should be placed in the every day practice. There is great need of a dialogue between nature and the built environment, especially for housing for low-income housing with limited sources. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 10.7 Internal Shadow Cast ‘ If lig h t d is a p p e a rs , th e sp ace d is a p p e a rs , tim e d is a p p e a rs .’ - Agustin Hernandez It is possible to control the amount of light allowed into every unit, and really work with the type of experience desired in the space. The path of light is predictable according to the latitude, altitude, and azimuth of the location. Every year, month, day there is a specific path in which the sun travels. If one works with nature, there are endless possibilities to take advantage of it, not only for functional purposes, but aesthetically. It is possible to control the quality of light, and the amount of light that comes in a space at specific times of the day. Fig. 10-10 Poetry in Barragan's Window (Barragan, 1999) 122 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. There are very good examples in the Middle East, with infinite examples of the use of brie de soleil. Or the master usage of Luis Barragan, in which light become the poetry and the central element within the architecture. The magic of light can be achieved with simple elements such as overhangs and fins. These devices are perfect for the benevolent climate of Southern California and Tijuana. 10.7.2 Solar 2 Solar 2 is a program that allows the study of the sun movement in an interior space. This program makes the calculations throughout the whole year, and at every hour of the day. It is a good tool to study the path of the sun in any open space. The calculations are achieved throughout the input of the area of the window, the size of the fins and shaded devices, as well as anything that blocks the passage of the sun into the space. The outcome results in the percentage of the area of the window in full sun, the percentage of the window in full sun and the calculation of the direct solar radiation that falls in the window x 100BTU. These topic are very useful when selecting the opening of the window, and it’s dimensions, in selecting the fin size, and offsets, as well as the size of the overhang and its offsets. There were a number of factors that were considered. The tests were taken to understand the sun path throughout the day, in various seasons of the year. The tests were: 1) East side unit facing south a) No overhead and no fins b) 2’ overhead, no fins c) 3’ overhead, no fins d) 3’-6" overhead, 1 ’ fin left and right 123 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2) West side unit facing south a) No overhead and no fins b) 3'-6" overhead , no fins c) 3’-6" overhead, 3’-6" fin on left side The different studies responded to the various needs. The west sun is the harshest of the day, and the shading devises responded according to these criteria. The results were different for the windows in the west and the windows facing east. Even though they are mirrored, physically, these two conditions don’t respond the same. The layout of the fins and overhead should be different in dimensions, in translucency degree. The west has a harsher lighting condition. Therefore the shading devices are designed to be bigger. For the units facing the east side, the balcony depth was designed to be 3’-6" feet in width, and the balcony depth on the west, was designed to be 4 fee in depth. These six inches made a difference, and both of these units have similar percentage of sun inside the space. These small changes can make a big difference in the quality of live in the space. The shading devices are another addition that improves the quality of live within the space. These shading devices take advantage of the balconies and become a part of the integral part of the every day life. During the summer the residents of the units can lower the shading devices, and in the winter they could raise them to allow light and heat into the space. With this, the facades become dynamic by changing in every season though out the year. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fig. 10-11 Manual Shading Devices, change with seasons o f the year 10.8 Importance of thermal mass The thermal mass in the exterior wall system affects the energy performance of buildings. There are three mechanisms in the process of Heat flows. They are conduction, convection, and radiation; usually conduction prevails on buildings. The most common way of heat flow is the R- value or the resistance. The higher the R-value of a material, the better the resistance heat loss or gain, depending on the situation. The U-value is a measure of the flow of thermal-heat transfer through a material. The U-factor is measured in the number of BTUs of energy passing through a square foot of the material in one hour for every degree Fahrenheit difference in temperature across the material (Btu/f^hrT). Materials that are good at resisting the flow of heat, which is high R-value, and low U-factor, can serve as insulator materials, and vice versa. Formula U * 1 12 R The other important factor in a material's performance is the heat capacity, which is how much heat a material can hold. The heat capacity is determined per unit area of the wall. For each layer in a wall system, the heat capacity is calculated by multiplying the density of 125 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. the material by its thickness times its specific heat. Whenever there are many layers in a wall, the total heat capacity is found by adding up the heat capacity for each layer. The R- value for some of the typical materials can be seen on the table below. Table 10-2 R Value fo r common materials .08 ~ 5 ~ 5 3.48 .79 11.10 4.00 10.9 Importance of insulation addition The basic construction method in Mexico is of concrete; construction method for low-income housing is of concrete block or brick with a layer of plaster cement. These houses tend to be very cold during the winter and very hot in the summer. Also the humidity seeps through after a period of time, making the building colder year by year. The composition of the wall is one inch of concrete and six inches of concrete block: R = 0.08 + 3.48 R= 3.58 U = 1/R U= 0.28 126 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Over a period of time, and with the passage of the seasons, the wall composition stores humidity. This makes the walls colder year by year. As a consequence each winter become colder, and the humidity within the wall increases fomenting the growth of mould. The structure of the building is affected, because the structural elements get humidity, causing the structure to weaken, and deteriorate endangering the lives of the inhabitants through possible failure. The addition of the 1 4 inch foam result in: R = 0.08 + 3.48 + 4.00 R= 8.58 U = 1/R U= 0.13 This reduces the U value by a 46.4%. The thermal capacity increases by almost half, ensuring better living conditions. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Chapter 11 11.1 Conclusion This work is based on the premise that there is a great need for affordable and sustainable housing in every country in the world. The aim of this study was to understand the natural elements in relationship to the man made construction for housing; Taking one of the most extreme conditions possible to construct in, yet one which often remains available in current urban conditions, the slope. This thesis divided its approach into two different sections, the structural and the environmental approach. Both of these aspects are necessary for the "well-being” of a building. 11.2 Structural Many settlements throughout the world occur on sloping sites. Up to now the ideal solutions for housing have been those on flat sites. This is a solution that goes against the logic of a sloping site. The current solutions uses cut and fill to create a flat site to design building just like those on flat land. The triangular profile of the resulting fill with variable fill depth is subject to differential settlement. This differential settlement is amplified in earthquakes, causing cracks in foundations and slab on grade. Building on a sloping site is more costly than on flat sites. However it is necessary to find a way to build systematically for the thousands of people who live in squatting areas close to the cities. The solution explored in this study was to mold the building to the site and not the site to the building. This approach reduces ground failure and uneven land settlement, which make the land vulnerable to earthquakes and major landslides. 128 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 11.2.1 Matrix The Matrix has been useful in the understanding of structural modules necessary to fit the building to hillsides. This matrix facilitates to find the best building configuration to fit a given slope including the steepest slope feasible. The matrix gives the allowance in dimension comparing regarding depth and height of the structural module. Table I l - l Typical dimensions Dimension Height Depth Minimum 7 ft. 11 ft. Maximum 12 ft. 16 ft. With the matrix the need to cut in the ground is minimal. This technique will minimize the construction of retaining walls, and conventional cut and fill technique, which promulgates the uneven settlement causing cracks in the foundation and slab on grade. 11.2.2 Terrace Housing Terrace housing has many advantages on hillsides. Taking advantage of the topography allows each unit to have its own entrance, and its own patio, giving it an individual identity and direct connection with the outside. The structure of the terraces uses the modules defined in the matrix. This allows structural walls to line up vertically for a clear load path and the structure becomes simple without too many force transfers. Two units are placed next to each other increases resistance against lateral movement. The terraces give each unit privacy and open space, and placing only two units next to each other allows cross ventilation in every single space. 129 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 11.2.3 Structural elements The structure for terraced housing depends on caisson foundations. This ensures stability for gravity and lateral loads with minimal disturbance to the ground. The foundations support the beam-wall that supports the structure. The wall acts as a beam, which spans from caisson to caisson. Six caisson foundations support every unit, two of them share the load with the other unit. The foundation is located 6 ft. off the edge. This configuration creates a negative bending moment in the beam wall that reduces the positive moment. This makes the structure very logical. The structure provides complete privacy without tall walls that block the view. Case study (A), allows the shading devices in combination with planters to ensure complete privacy because the unit above has no view of the unit below. The 45- degree visual angle goes beyond the unit bellow. Wood construction has proven to be safer than other materials due its lightness and flexibility. Looking at the conditions of Tijuana, wood is very much viable to be used. The economics of the city allows the wide usage of this material that is very scarce in the rest of the country. It is my strong believe that though other materials such as concrete are available and people have the know how of its construction, it would be a lot safer in earthquake performance to use wood construction. It is my desire that this study triggers the consideration towards this material. 11.3 Solar envelope Just as using the matrix provides a framework for an intelligent structural solution, the solar envelope provides a framework for light and air. It is important to understand that the solar access depends on the location where the building is erected. In this case, Tijuana is located very close to the ocean at a 32-degree latitude. This location ensures the city access to the sun throughout the whole year. This latitude is exposed to primarily the west 1 30 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. winds, which is ideal for the natural ventilation. Understanding the site before hand allows the outcome of the design to be intelligent and sensitive to the surroundings. From case study (A), there are a number of outcomes that were determined. 11.3.1 Orientation The orientation of the site determines the size and shape of the solar envelope. The project is oriented north south, having the south as the lowest point. The south, which is the front fagade, has the most solar access throughout the year. With this we have determined the unit to have solar access for six hours throughout the whole day, every day of the year. Other orientations vary greatly. The east west, having the west as the lowest point enjoys solar access throughout the whole day. The west has the harshest type of light; therefore some other approach should be taken. The difference that all the orientations have should studied individually. This study has focused only on the south orientation, with solar access in the east and the west. Future studies should include the study in the other orientations, and developing a chart or characteristics of differences and similarities, and another one of advantages and disadvantages in the study. 11.3.2 Determination of Fences Privacy fences are placed at the boundaries of each unit at a height of 10 feet. The fences determine the extent of privacy afforded to the unit in the winter and the summer. Combining both of these envelopes, the composite envelope is generated. This determines the shape of the building. Due to the flexible shape, the volume changes throughout the year, making the building dynamic according to the seasons. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table 11-2 Typical Heights B alcony (fro m to p to bottom ) Height (closer to the house) Height (edge of terrace) 1 5'-2" 2 13’-5” 6*-r 3 11’-9" 6’-5" 4 12’-4" 15’-0" * The heights are measured from inside out The height of the pergola can be determined according to the seasons. These shading devices will change in height and character according to the time of the year. As an example, in the summer these devices are going to be placed higher up with fabric to ensure shade on the terrace and inside the unit. In the winter the fabric is removed, exposing the framework which allows solar access, and can also be used for hanging clothes. This open space will represent the characteristics of the dwelling inhabitants. 11.3.3 Two units side by side per structure There are eight units per terrace unit. Two units are located next to each other as mirror image. These units work the same in opposite directions. One unit has solar access in the morning, the other unit has solar access in the evening. The placement of only two units as opposed to three or four in a row ensures cross ventilation in every single room within the unit, except the bathroom. This reduces the need to use air conditioning and heating devices. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 11.3.4 Shading devices on the windows (East West) Shading devices allow direct sunshine in winter and protection from the heat of summer. Taking advantage of the balcony entrances, the shading devices hang from these walkways, and are tied to the top rail of he banister. With these devices, the residents of the units take an active role in creating a ritual in their every day lives, by raising and lowering the shading devices according to their own needs. This avoids the static view, again making the building dynamic. 11.4 Environmental Control The openings in the units are not randomly selected but are a result of a careful study of the shading patterns within the unit. That is the main reason why the unit has cross ventilation. The more the light that enters into the unit, the higher is the temperature. In addition to the careful selection in the openings in the unit, there has been an addition of insulation. In the traditional way of construction in Mexico, there is no thought given to provision of insulation. Cheap construction in the near future is the primary concern. This is, however, short sited because it inevitably results in leakage, mould, and loss of thermal capacity of the units. This leads to undesirable extreme condition of discomfort for the inhabitants - extreme cold in the fall and winter. The units, over time, fall into a state of disrepair and decay. Just by adding 1 4 inch of foam, the R-value increases almost fifty- percent, thereby greatly improving thermal performance of the unit. The care for little details result in the betterment of the quality of life for the residents. Building on sloping sites is more expensive than building on fiat sites. However, there is little or no option for the low-income class than live in self-built squatting areas near the metropolis. It is important to learn from the past and avoid results such as the one after the 1 33 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Earthquake in El Salvador in January 2001. When the quality of life becomes the number one priority the effects of catastrophes are diminished, and the every day life is enhanced through a “ ritual". All the elements of nature work together. It is ridiculous to ignore the environment, and try to control it with only the knowledge of technology. Buildings should be able to adapt to the natural environment. It is time to stop ignoring the plenitude of resources in nature, and start to use them to our own advantage. Reducing the energy usage results in a comfortable living environment. I believe that just because the design is for the low-income group, the quality of their lives need not be poor. As an architect, I have the responsibility and the knowledge to improve every day life through intelligent application of careful detail during the design process. This thesis has helped me to realize this responsibility in providing good quality housing for endangered people that live in the slopes near the urban areas such as Tijuana, Mexico. Maili Sekiguchi, August 2001 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Bibliography Abbott, Derek and Kimball Pollit. Hill Housing, a guide to Desion and Construction. New York: Whitney Library of Design, 1981. Aldrete-Haas, Jos6 Antonio. L a deconstruccidn del estado mexicano pollticas de vivenda. 1917-1988. Mexico City, 1991. Anderson, Bruce. Solar Energy: Fundamentals in Building Design. Harrisville, New Hampshire: McGraw-Hill Book Company, 1977. Amal Simon, Luis and Max Betancourt Suarez. Relaamento de Construcciones Para el D. F. Mexico D.F.: Editorial Trillas, 1996. Beall, Christine. Masonry Design and Detailing. New York: McGraw-Hill, 1997, Sedition. Bemardini, Alberto, ed. Seismic Damage to Masonry Buildings. Rotterdam: A.A Balkema, 1999. Berretta, Horacio. Vivienda v Promocibn para las Mavorias. Buenos Aires: Editorial Hvmanitas, 1987. Blanton, Richard E. Houses and Householeds. a Comparative Study. New York: Plenum Publishing Corporation, 1994. Burley, S. and M.E. Arden. 18t h National Passive Solar Conferences. Washington, D.C, American Solar Energy Society, 1993. Campos, Ricardo. La oarticioacidn del Sector Publico en la Vivienda. Estado de Mexico: Univerdiad Autdnoma del Estado de Mexico, 1993. Carver, Norman F. Jr. Italian Hilltowns. Kalamazoo, Michigan: Document Press, Ltd., 1980. Dowrick, D.J. Earthquake Resistant Design: A manual for engineers and architects. New York: John Wiley & Sons, Ltd., 1978. Fang, Hsai-Yang, Introduction to Environmental Geology. New York: CSC Boca Raton Press, 1997. Frampton, Kenneth. Tadao Ando and the Cult of Shintai: The Yale Studio and Current Works. New York : Rizzoli, 1989. Gilbert, Alan, Ed. Lawrance Herzog. Housing and Land in Urban Mexico. Monograph Series, 31. San Diego: University of Southern California, 1989. Imre, Laszlo & Andras Bitai Ed. ISES Solar World Congress Budapest 1993: Harmony with Nature. Volume 1 Energy Poicv. Environment. Education. Budapest: Hungarian Energy Society, 1993 135 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. INEGI (Institute Nacional de Estadistica Geografia e Infomnatica). VII Censo General de Poblacion v Vivienda. Mexico City, Nov. 2000 Knowles, Ralph L. Sun Rhythm Form. Cambridge, Mass.: The MIT Press, 1981. Luna, Paulino. Recycling and Waste Management in San Dieoo and Tiiuana. Bi-national Planning and Coordination Committee, Forth Annual Bi-national Forum, Tijuana, 1997. McCov. E. “ Four Schindler houses of the 1920s". Arts & Architecture. Sept. 1953 p.14 Rouillard, Dominique. Building the Slope. Hillside Houses 1920-1960. Paris: Arts & Architecture Press, 1987. Simpson, B J, and M T Purdy. Housing on Sloping Sites: a Design Guideline. New York: Construction Press, 1984. Valenzuela Arce, Jos6 Manuel. Empapados de Sereno: El movimiento Urban Popular en B.C. Tijuana: El Colegio de la Frontera Norte, 1991. Van der Ryn, Sim and Stuart Cowan. Ecological Design. Washington, D.C.: Island Press, 1996. Schierie, GG. Ed. CUREE Report, Northridge Earthquake Field Investigations: Case Studies of Woodframe Damage. Vergun, Dimitri "Case Study 2: Gallagher,” Northridge Earthquake Field Investigations: Case Studies of Woodframe Damage, 2001. Turner, John FC. "Housing by People.” Architectural Design. April 1976, volume.46 page. Estado de Baja California, Reglamento de la Ley de Edificaciones. Tijuana, 1991. IMPIan. Tiiuana 2000: Escenario de Crecimiento. Unpublished paper. United Nations Center for Human Settlements, Global Report on Human Settlements 1987 Oxford: Oxford University Press, 1987 Webster's New Dctionary, third collage edition, (Simon & Schuster, Inc., New York, 1988) Yeh, Uen-Fang Patricia. Computer Aided Solar Envelope Design. Los Angeles, University of Southern California Masters Thesis, 1992. Yeh, Uen-Fang Patricia & Marc Schilerm Assoc. Prof. Hovt Street Yard Redevelopment Plan: A Case Study Usino an Interactive Computer Program for Defining and Drawing Solar Envelopes. Los Angeles, University of Southern California. 1992. Web Sites Anderson, L.O. Woodframe House Construction, <http://www.craftsman-book.com/cai- bin/SoftCart.exe/cbcstore/prodpaaes/info/wfh/chpQ1 .htm?E+cbcstore> 136 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Ando, Tadao. Biography. <http://uo.arch.hku.hk/~fwwu/viscom2/assian3/top3.html> Castellanos, Delia, Carlos Santin and Richard Wright. San Diego State University. San Dieqo-Tiiuana International Border Area Planning Atlas. 1994 <http://irsc.sdsu.edu/atlas/maos/map11 -12.pdf> <http://www-rohan.sdsu.edu/~irsc/atlas/pics/slop.oif> <http://www-rohan.sdsu.edu/~irsc/atlas/text/slopenq.html> CISPES National Office El Salvador Earthquake Talking Points. Jan. 15,2001. <http://www.cisoes.oro/html/cispescttes.html> Gray, Donald H. ‘Erosion Control Practices: Toward the Year 2000”, last opened 27 Feb. 2001. <http://www.landscapeonlin.com/lolpaaes/- editorial00/elementalconcems/erosioncontrol.9702ErosionControPractices.htm> INFONAVIT, Ultima Reforma Publicada en Diario Oficial de la FederaciOn. Sept. 13, 1999. < http://148.243.238.171/data/naveoa.htm> Kratochvil, Jan. March 5,2001. <http://www.fa.vutbr.cz/archiweb/index.html> Moin, Fazal. Disaster and Development. Pakistan Red Cross Society, March 18 ,2001. <http://www.jonoudismotconf.oro/moin.htm> Municipio de Tijuana, 1994. <http://tvphoon.sdsu.edu/TJWATER/HOMEPAGE/tiwlanduse.html> Newman, Oscar. “ Defensible Spaces" Principals. Chapter 1, March 13,2001 <http://www.defensiblespace.com/book.htm> Roper. Tessa, Tijuana River National Estuarine Research Reserve. San Diego State University. Southwest Center for Environmental Research and Policy fSCERPI. 1998-99. <http://typhoon.sdsu.edu/twrp/tirecent.htmlGoat> Sinah, Tapen. Insurance. Development, and Economic Growth of Mexico. 1998 <http://allman.rhon.itam.mx/~tapen/classnotes/RMI/population/sld004.htm> Weinstein, Elizabeth. United States: Crime Stioma Plagues Public Housing. May 12,1998. <httP://www.rferl.ora/nca/features/1998/05/F.RU.980512131355.html> World Resources 1996-97. Urban impact on natural sources. <http://www.wri.org/wri/wr-96-97/ee txt2.html> ZETA Publications. Tamayo, Ana Ptricia. Las Zonas mas oeliarosas. si llueve. < http://www.zetatiiuana.eom/edicion/anteriores/1392/refortakez2.htm> Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

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Asset Metadata

Creator Sekiguchi, Maili (author)

Core Title Terrace housing: A conscious solution

Degree Master of Building Science

Degree Program Building Science

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

Tag Architecture,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Advisor Schierle, Gotthilf Goetz (committee chair), Knowles, Ralph Lewis (committee member), Schiler, Marc (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c20-317042

Unique identifier UC11259007

Identifier EP41851.pdf (filename),usctheses-c20-317042 (legacy record id)

Legacy Identifier EP41851.pdf

Dmrecord 317042

Document Type Thesis

Rights Sekiguchi, Maili

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...

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