A modified response spectrum method based on uniform probability spectrum

Abstract

The traditional response spectrum method (RSM) based on the mean peak spectrum (MPS) requires the assumption of equal modal peak factors, which may exert a major impact on the accuracy of the mean peak responses of structures under seismic excitation. The inherent reason behind this lies in the fact that no uniform probability of exceedance exists for the MPS curve over the range of frequency considered. To tackle this problem, an alternative spectrum characterized by the fractile responses of single-degree-of-freedom (SDOF) systems with uniform probability of exceedance at a specified percentile level, termed as the uniform probability spectrum (UPS), is proposed and adopted in the complete quadratic combination (CQC) rule to compute the structural fractile responses in the frame of RSM under Gaussian ground motion. It can be further observed that the fractile values of different structural responses are of the same probability of exceedance as that specified for the UPS used. Applications to different types of buildings are presented to validate the feasibility of the proposed UPS-based RSM in real engineering practices.