Evaluation of the accuracy of the Multiple Support Response Spectrum (MSRS) method

The MSRS rule is a response spectrum method for analysis of multiply supported structures subjected to spatially varying ground motions. This paper evaluates the accuracy of the MSRS rule by comparing MSRS estimates of mean peak responses with corresponding “exact” mean values obtained by time-history analysis with ensembles of simulated support motions. The simulated support motions are realizations of an array of non-stationary processes with a specified coherency function, generated with a simulation approach developed elsewhere by the authors. These sets of motions are characterized by consistent variability at all support points, and thus, are appropriate as input for statistical analysis. The structural systems considered are four bridge models selected to have vastly different structural characteristics. The responses examined are pier drifts, which are quantities particularly important in performance based design of bridges. Results indicate that the MSRS method is a reliable analysis tool.