The evaluation of nonlinear seismic demands of RC shear wall buildings using a modified response spectrum analysis procedure

Abstract

In the standard Response Spectrum Analysis (RSA) procedure, the elastic force demands of all significant vibration modes are first combined and then reduced by a response modification factor (R) to get the inelastic design demands. Recent studies, however, have shown that it may not be appropriate to reduce the demand contributions of higher vibration modes by the same factor. In this study, a modified RSA procedure based on equivalent linearization concept is presented. The underlying assumptions are that the nonlinear seismic demands can be approximately obtained by summing up the individual modal responses, and that the responses of each vibration mode can be approximately represented by those of an equivalent linear SDF system. Using three high-rise buildings with RC shear walls (20-, 33- and 44-story high), the accuracy of this procedure is examined. The modified RSA procedure is found to provide reasonably accurate demand estimations for all case study buildings.