ABSTRACT
Recent updates of international codes on seismic analysis and design of buildings reflect the threats to existing buildings under more frequent earthquakes foreseen in the near future. The objective of ensuring structural safety of these buildings under seismic action intensifies their performance assessment for which pushover analysis is widely accepted as a rapid and reasonably accurate method. However, approaches based on limit analysis procedures (both static and kinematic theorems of plasticity theory) have also been equally popular for addressing issues related to structural safety in situations of extreme loads that can jeopardize buildings and could threaten the lives of inhabitants. A comparison between the forecast of design base shear obtained by pushover analysis and collapse loads based on limit analysis procedures is advantageous to establish confidence in the obtained results. In this chapter, we discuss the analytical procedures to determine the collapse loads by limit analysis and pushover as well. Comparison of the results obtained by employing the above tools on multistory moment-resisting reinforced concrete frames subjected to seismic loads is presented. Displacement-controlled pushover analysis is performed on the building frames whose input parameters like axial force-bending moment yield interaction and moment-rotation are derived based on the detailed mathematical modeling presented in earlier chapters. Bounds for collapse loads based on both static and kinematic theorems of limit analysis are obtained using mathematical programming tools. Computer code used to determine the collapse multipliers is given in Chapter 6.
