OPTIMIZATION OF ARCHITECTURAL BUILDING SYSTEMS IN EARTHQUAKE PRONE AREAS OF INDIA

Abstract

Earthquake is a natural phenomenon; its fury is unparalleled in its destructiveness. It leaves behind ruined settlements, causes destruction of the built environment and creates several human problems. Earthquake disasters in majority of cases are due to procreated vulnerability from human action. Earthquake by itself does not kill anybody; it is the manmade structures, which kill men. India is one of the most susceptible countries to damaging earthquakes. Five earthquakes occurred in the semi-urban areas of India in the recent past viz. Uttarkashi earthquake of 1991, Latur earthquake of 1993, Jabalpur earthquake of 1997, Chamoli earthquake of 1999 and Bhuj earthquake of 2001. Damage scenario in these events has been more less similar, where disaster was caused largely by due to ignorance of the local inhabitants about the behavior (response) and poor strength of their buildings to resist the imposed seismic loads. Most of such construction fails to maintain their integrity on exposureto an earthquake at the affected site. Earthquake is a natural hazard but repeatedly every disaster confirms that people have yet to learn to live with earthquakes in India. This dissertation endeavours to develop a system for the creation of an earthquake resistant living environment for the earthquake prone areas of India.Various seismological parameters, theories; concepts have been studied from architectural point of view to form the technological background for the formation of this dissertation. Building code in India has been drafted recognizing the need for detailed analysis as far as structural design of abuilding is concerned. However the performance of abuilding on exposure to earthquake cannot be judged fully by studying just this as an individual unit. There are anumber of factors, which are invariably associated with its likely performance in an earthquake. Besides structural detailing the architectural configuration and how and where it is stitched in acity's fabric, its maintenance and use patterns, also affect its response in the event of an earthquake to aconsiderable extent. Alarge proportion of population in India is illiterate and building stock is of non-engineered type. In such circumstances codal provisions are not generally referred by masses. Measures suggested in guidelines formulated by IAEE committee are certainly useful to agood extent. However, in this context some more details are needed with respect to building technology and architectural configuration, aimed to impart required structural strength with almost no extra cost or negligible increase in cost. This thesis takes alook at seismic codes of India as well as ofthe other countries worldwide. In atypical Indian city there are anumber of architectural elements, which are repeatedly used by people and have proved disastrous in past earthquakes. Such architectural, urban design elements if identified, may either be avoided while designing abuilding /area or appropriately detailed out to impart adequate resistance or resilience to withstand an earthquake. This calls for an in-depth study of earthquake damages to the architectural building systems in India in past earthquakes with reference to architectural development and the knowledge should be disseminated to the intended users. After every devastating earthquake poor detailing of non-structural, architectural elements, inadequate juxtaposition of built masses, is pointed out after damage investigations in avery superficial manner. Identification of vulnerable architectural features with respect to their configuration and constructional detailing of Indian building systems has not been done so far. This dissertation investigates earthquake damages through extensive surveys of earthquakeaffected areas just after the occurrence of the events and literature browsing. It goes to analyze the behavior and performance of architectural building systems during an earthquake to formulate the base for the identification of parameters for optimization of architectural builtforms and building technology in the earthquake prone areas of India. Anumber of earthquake damage studies undertaken worldwide have been looked in. It is found that most of the vulnerability functions and damage matrices developed are not suitable in Indian context, where a large proportion of population is living in vulnerable and unsafe buildings from earthquake point of view. This dissertation conceptualizes amodel for the assessment of likely performance Indian building stock on exposure to an earthquake, considering the various dimensions of living and seismic environment. The synthesis of environmental assessment comprised two basic tasks. First the determination of building parameters which have major influence on vulnerability and second to quantify their influence. Based on analytical survey done by the author of earthquake-affected areas of Latur and Jabalpur a set of indices has been established. The selected indicators have been highlighted and their validity has been examined.

Structural strength of building system, fenestration characteristics, soil foundation details, building material used in construction and building configuration are identified as the primary indices, which largely affect the extent of damage. Some secondary parameters which affect the performance of abuilding system on exposure to an earthquake and refer to the presence / absence of architectural decorative elements are identified as Correction factors in architectural development. The model for the assessment of likely performance of living environment (RAC) has been developed in this dissertation considering the characteristics of both the living as well as seismic environment. The grading with reference to the vulnerability of the area in question will act as aguideline to suggest optimum measures for its restructuring. The model developed in this investigation is based on damage data obtained from surveys and damage reports of past earthquakes in India and is supposed to provide a more realistic picture of seismic vulnerability of Indian building stock. The use of RAC has been demonstrated in the case of Jabalpur, India. In India alarge proportion of existing building stock is in an advanced state of decay and the newly built stock suffers from inadequate construction and design standards. Although 23% of the workers are employed in the construction industry only a small proportion of these are trained to use modern techniques of construction. This has resulted in highly vulnerable building stock as was evidenced in the recent earthquakes of Uttarkashi, Latur, Jabalpur, Chamoli and Bhuj.

Creation of living environment is aprocess of giving physical form to human's socio-economic needs and aspirations. Living environment at different places have always been created, modified and used by the users in a different manner and are therefore very different in character. Optimization is directly related to human activity in any field and has developed into a multi-disciplinary branch of science. The optimal design of builtforms targets to developing economical and reliable structures and systems for different environmental conditions and technological constraints. Considering the importance of not only physical factors related to architectural development but also the socio-economic and cultural dimensions this dissertation conceptualizes optimization parameters. It endeavour to suggest solutions for optimal design of building systems with reference to their configuration, fenestration design, interior layouts, constructional details, useoflocally available materials, and technology. The inventory based on behavioral analysis of architectural building systems can provide a base for the choice of optimum material, and technique with optimum level of earthquake resistance considering the seismicity of the area in question. Theoretical and analytical contributions of this thesis are presented in addition to the suggestions for desirable further research.