Multiphase Performance Assessment of Structural Response to Seismic Excitations

An alternative approach to the traditional method for performance assessment of structural systems is proposed. Denoted herein as the M-PARS method, this new approach is capable of tackling clusters of structural behavior under seismic excitations from one hazard level to another due to, for example, variations in the nature of excitation characteristics. The method's ability to recognize and process different clusters (i.e., phases) separately enables it to yield performance estimates with higher accuracy and less variability. The proposed M-PARS methodology is a step up compared to existing state-of-the-art (albeit conventional monophase) approaches. In the present study, M-PARS is first formulated in general terms, and then applied to a specific case study involving bridges with skew-angled seat-type abutments to demonstrate its salient features. In this study, the sensitivities of the median estimates of seismic response to variations in bridge geometry parameters and ground motion characteristics are investigated, and direct comparisons are made with a conventional monophase method to quantify the advantages afforded by the proposed method. (C) 2015 American Society of Civil Engineers.