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Site Effects in Structural Performance Estimation

Domniki Asimaki, Wei Li, & Michalis Fragiadakis

Accepted 2010, SCEC Contribution #1343

We study how the selection of site response model affects the structural performance estimation when the latter is assessed via synthetic ground motions. For this purpose, we compute broadband ground motion synthetics for 6 earthquake scenarios of a strike-slip fault rupture, and estimate the ground surface response for 24 soil profiles corresponding to seismogram stations in Southern California. We use both visco-elastic and nonlinear analyses for the site response simulations, and evaluate the ground surface motion variability that results from the soil model selection. Next, we subject a series of bilinear single degree of freedom oscillators to the ground motions computed using the alternative soil models, and evaluate the consequent variability in the structural response. Results show high bias and uncertainty of the inelastic structural displacement ratio predicted using the linear site response model for periods close to the fundamental period of the soil profile. The amount of bias and the period range where the structural performance uncertainty manifests are shown to be a function of both input motion and site parameters. We finally derive empirical correlations between the site parameters and the variability introduced in structural analyses based on our synthetic ground motion simulations.

Asimaki, D., Li, W., & Fragiadakis, M. (2010). Site Effects in Structural Performance Estimation. Earthquake Spectra, (accepted).