Seismic behavior of multistory RC building frames with vertical setback irregularity

This paper is the second of two companion papers that aimed to examine the behavior of irregular buildings subjected to seismic excitation. In the present study, seismic response of the building frames with setback irregularity has been determined. To achieve this purpose, building frames with different geometrical configurations of setbacks are modeled and analyzed using nonlinear dynamic analysis by subjecting them to an ensemble of 27 ground motions to generate 21060 nonlinear dynamic analysis results. These results are compiled to create a seismic response database consisting of parameters such as maximum roof displacement, maximum interstory drift ratio, maximum plastic hinge rotation and collapse risk parameters. Furthermore, nonlinear regression analysis is conducted on this database to propose simple equations to estimate the seismic response parameters. Finally, the proposed equations are validated for two-dimensional and three-dimensional building models, and applicability of the proposed equation in performance-based and displacement-based designs is briefly discussed. Copyright (c) 2013 John Wiley & Sons, Ltd.