Multi-support excitation of single span bridges, using real seismic ground motion recorded at the SMART-1 array

The real spatial heterogeneity of the ground accelerations in recorded events at the SMART-1 array in Taiwan show more random variation than is assumed by SVEGM type models. Rather than employing some exponential type best-fit for the absolute coherency between two dissimilar spatial locations, real multi-station data from SMART-1 is used to generate a more detailed picture of the spatial heterogeneity present. A novel correction scheme is employed to reprocess the SMART-1 data. This paper considers the errors, in seismically induced forces, that can be accrued if identical support excitation (ISE) analysis is used in place of a multi-support excitation (MSE) analysis. A spectrum of bridge spans and spatial horizontal alignments are investigated using contoured polar response spectra. The effect of structural mode coupling is investigated. The conditions under which an ISE analysis is not conservative are reported.