Exploratory Study of Comparison between Ultimate Strength and Performance Based Design for Reinforced Concrete Structures Subjected to Seismic Loading

Abstract

Structural design of RC buildings has been going through a transition from allowable stress design approach (ASD) to the ultimate strength design approach (USD) leading to the present performance based design philosophy. PBD ensures that the members and structure as a whole reach a desired demand level and includes service, strength and capacity requirements. In the presented study a nonlinear analysis and design has been conducted on an intermediate rise RC building considering all seismic zones as specified by Unified Building Code in order to compare the USD and PBD approaches. Furthermore a comparison of different shear wall modeling techniques is presented along with modification to design methodology to make the structural design more economical. For the USD, UBC97 and for PBD, ATC-40, FEMA-273 and FEMA-356 guidelines are used. The presented results reveal that the USD approach is unable to predict the soft story mechanism and shear failure governed the final failure in all seismic zones, whereas the flexural design was found to be adequate as inelastic deformations remained within the acceptable limits. However, capacity analyses revealed a non uniform damage throughout the building in contrast to PBD approach.