Bidirectional pushover analysis of irregular structures

Abstract

The Nonlinear Static Pushover analysis is extensively used for the seismic assessment of structures for every type of building. The paper proposes the Bidirectional Pushover Analysis (BPA) to overcome the torsional problems in plan and elevation of asymmetric buildings, when bidirectional ground motion is considered. Different reinforced concrete frame structures are selected and modeled in 3D. The N2 method is then applied bidirectional to estimate the actual non linear response. Results in term of floor interstory drifts and floor rotations from the bidirectional pushover analysis, are compared with the nonlinear dynamic time history analysis. A suite of twenty European bidirectional seismic ground motions were selected. It was found that BPA matches with the bidirectional non linear time history analysis when the ratioY/X is around 0.6, which is different from the ratio of 0.3 provided by the European seismic code when bidirectional linear analysis is performed.