Performance Based Design Of Shear Wall Building

Abstract

Earthquakes are known to produce one of the most destructive forces on earth. It has been seen that during past earthquakes many of the buildings were collapsed. Therefore, realistic method for analysis and design are required. Performance Based Design is the modern approach for earthquake resistant design. It is an attempt to predict the performance of buildings under expected seismic event. A structure designed with Performance Based Design (PBD) concept does not developed undesirable failure mechanism during earthquake. The analysis can be performed on new as well as existing buildings and the performance of buildings in future earthquake can be evaluated. The present study is an attempt to understand the fundamentals and procedure of Performance Based Design of R.C.C. shear wall building. A Nonlinear Static Analysis (Pushover Analysis) is widely used to obtain the inelastic deformation capability of building, which depends on localized damage (hinges formation) in various elements of building. The results of push analysis are compared using default hinge properties as per ATC 40 and user defined hinge properties as per stress strain relationship. In practice, ATC 40 based default hinge properties are used due to convenience and simplicity. But the observation clearly show that the user defined hinge model is better than the default hinge model in reflecting nonlinear behavior compatible with the element properties. The software used for performing performance based design is ETABS 9.07. Pushover analysis is based on static nonlinear analysis performed by imposing an assumed distribution of lateral loads over the height of a structure. The lateral loads are incremented monotonically from zero to the ultimate level corresponding to the incipient collapse of the structure. The response behavior of structure is evaluated by measurement of strength of structure. There are several methods for estimating seismic demands for performance-based design of buildings. The accuracy of design is based on applied pattern of loads inducing deformation in the structure which should be similar to that induced by the earthquake ground motion. The result of pushover analysis in term of capacity, demand and performance point are compared as obtained from inverted triangular distribution of lateral load pattern based on codal formula, and lateral IV load distribution generated from site specific response spectra and time history analysis. Performance criteria are described in terms of performance levels and hazard levels. The design objectives in current building codes consider as life safety in minor and moderate earthquakes, and collapse prevention in major earthquake. However, the actual design in achieving the objectives is not known. Performance based design is iterative in nature compared to one step analysis and design as per IS: 1893(Part1)-2002. The process of analysis and design is repeated till expected performance objectives are meet. 20 story shear wall building is considered for performance based design. Basic information related to Performance Based Design are discussed in Chapter 1. It also includes objective of study and scope of work. Chapter 2 presents the literature review on topic related to performance based design. Modeling techniques and software application of ETABS (Extended Three Dimensional Analysis of Building Structure) with theoretical derivation of performance point as per ATC 40 are covered in Chapter 3. Derivation of hinge properties and comparison of 3D frame result using different hinge properties are discussed in Chapter 4. Pushover analysis result in term of capacity, demand, performance point, hinge formation pattern at performance point for lateral load distribution over the height of structure considering time history and response spectrum is discussed in Chapter 5. In Chapter 6, site specified time history and site specific response spectra analyses are presented. Performance based design objective and criteria are discussed in Chapter 7. Also 20 story shear wall building design based on performance level is presented. Finally in Chapter 8, summary of study, conclusions and future scope of work are given.