Spectral matching RotD100 target spectra: Effect on records characteristics and seismic response

This article investigates three different approaches to generate seismic input compatible with RotD100 design spectra: (1) separately matching each horizontal component to the target spectrum, (2) separately matching and then scaling-down the records to improve the match and (3) directly pursuing the match of RotD100 by simultaneously modifying both horizontal components. We examine the strong motion characteristics of the resulting records individually and their variability as suites of input records. The records generated, along with a set of amplitude-scaled records, are used as input for bi-directional non-linear response history analyses of idealized single column reinforced concrete bridge piers with different geometric and reinforcement characteristics. It is shown that the records generated pursuing a direct match of the target spectrum attain the closest match, retain better the strong motion characteristics of the seed records and their horizontal components exhibit a spectral variability comparable to suites of amplitude-scaled records. Regarding the effect on seismic response, the suites constructed separately matching each component consistently imposed larger peak inelastic and total energy demands than all other suites. Directly pursuing the match of RotD100 generated responses close but consistently below the expected from amplitude-scaled suites. The best results were obtained using the direct match methodology but using as target 110% the RotD100 spectrum as required in ASCE 7-16.