Probability-consistent spectrum and code spectrum

Abstract

In the seismic safety evaluation (SSE) for key projects, the probability-consistent spectrum (PCS), usually obtained from probabilistic seismic hazard analysis (PSHA), is not consistent with the design response spectrum given by Code for Seismic Design of Buildings (GB50011-2001). Sometimes, there may be a remarkable difference between them. If the PCS is lower than the corresponding code design response spectrum (CDS), the seismic fortification criterion for the key projects would be lower than that for the general industry and civil buildings. In the paper, the relation between PCS and CDS is discussed by using the ideal simple potential seismic source. The results show that in the most areas influenced mainly by the potential sources of the epicentral earthquakes and the regional earthquakes, PCS is generally lower than CDS in the long periods. We point out that the long-period response spectra of the code should be further studied and combined with the probability method of seismic zoning as much as possible. Because of the uncertainties in SSE, it should be prudent to use the long-period response spectra given by SSE for key projects when they are lower than CDS.