Investigation of Effects of Capacity Spectrum Method on Performance Evaluation of Multi-Story Buildings According to the IRAQI Seismic Code Requirements

摘要

The aim of this study is to assess the performance objectives defined in the Iraqi Seismic Code (ISC) in order to make a realistic evaluation related to Performance-Based Seismic Design (PBSD) of multi-story reinforced concrete buildings and also to compare and evaluate structural response demands obtained from nonlinear static analysis procedures according to two versions of the capacity spectrum method (CSM) which are recommended in ATC 40 and ATC 55. Two groups of three-dimensional RC buildings with different heights, designed according to Iraqi Building Code Requirements for Reinforced Concrete (IBC), are investigated. Pushover analyses are carried out to determine the nonlinear behavior of the buildings under three different seismic hazard levels, for two Iraqi seismic zones, of earthquake loads. In order to determine performance levels of the buildings, maximum inter-story drift demands and plasticizing sequence are determined and compared with the related limits using the CSM recommended in ATC 40 and ATC 55. From the results of this research, it can be concluded that RC buildings designed according to the Iraqi codes sufficiently provide the performance objectives stipulated in the ISC. Comparing structural response quantities obtained from the two versions of CSM, effects on performance evaluations of the buildings are investigated comparatively, as well.