PREDICTION OF PEAK SEISMIC RESPONSE OF ASYMMETRIC BUILDINGS UNDER BI-DIRECTIONAL HORIZONTAL GROUND MOTION USING EQUIVALENT SDOF MODEL AND ITS APPLICABILITY

Abstract

The applicability of equivalent SDOF model for the prediction of nonlinear peak response of multi-story asymmetric building subjected to bi-directional excitation is discussed in this paper. In the first part, the formulation of two independent equivalent SDOF models representing the first and second modal responses is summarized, and the critical conditions of which the asymmetric building should satisfy are discussed. In the latter part, nonlinear time history analyses of three four-story torsionally stiff (TS) and three torsionally flexible (TF) asymmetric buildings are carried out and these results are compared with the predicted results. The results show that the proposed procedure satisfactorily predicts the peak response displacement of a only TS asymmetric building. Therefore the applicability of equivalent SDOF model discussed in this paper should be limited to TS buildings. The classification of TS buildings can be made from the torsional index defined based on mode shape.