A new lateral load pattern for pushover analysis of asymmetric-plan structures

Abstract

Pushover analysis has become one of the most commonly used nonlinear static procedures (NSP) for the seismic estimation of structures in engineering practice. In this paper, a new lateral load pattern is presented to enhance the accuracy of conventional pushover analysis (CPA) procedures for evaluating seismic behaviors of asymmetric-plan multistory buildings, which has considered the effect of torsion and higher modes. This spatially distributed lateral load pattern is proposed eventually by introducing and calculating the coefficients of adjustment and distribution respectively. The performance and accuracy of the proposed spatial pushover analysis (SPA) procedure is verified against two distinct multistory buildings with irregular plans subjected to five medium-to-strong ground motions. Furthermore, the peak responses in terms of base shear, roof displacements, interstory drifts, plastic hinge rotations and pushover capacity curves obtained from the SPA method are compared with those from nonlinear time history analyses (NTHA), and CPA procedures. The comparative results indicate that new lateral load pattern agrees very well with the NTHA procedure. The proposed SPA procedure shows its efficiency and overcomes the limitations of current extended pushover methods to assess the seismic responses of asymmetric-plan structures. It is strongly suggested that the new load pattern as an applicable method for pushover analysis of asymmetric-plan structures.