Eta-based Conditional Mean Spectrum, a New Design Spectrum for Industrial Facilities

Abstract

The target spectrum which has been used most frequently for the seismic analysis of structures is the Uniform Hazard Response Spectrum (UHRS). The joint occurrence of the spectral values in different periods, in the development of UHRS, is a key assumption which remains questionable. The Conditional Mean Spectrum (CMS) has been recently developed by Baker et al. as an alternative for UHRS. The CMS provides the expected response spectrum conditioned on the occurrence of the target spectral acceleration value in the period of interest which can be accounted as an improvement of the UHRS. In order to enhance the CMS, the correlation between the Peak Ground Velocity (PGV) and the spectral acceleration values has been investigated in the current study, and finally, a newer form of target spectrum has been proposed. It is shown that the emerged new spectrum, named Eta-based Conditional Mean Spectrum (E-CMS), is more efficient than the conventional CMS in order to enhance the UHRS, especially in the case of industrial facilities.