Influence of high-frequency components of hybrid-broadband and deterministic CyberShake ground motion simulations on nonlinear response analyses of buildings

Nenad Bijelic, Ting Lin, & Gregory Deierlein

Under Review 2018, SCEC Contribution #8038

Physics-based ground motion simulations are advancing to a state of enabling detailed characterization of extreme earthquakes holding promise for providing novel insight to questions of engineering concern. However, an important step toward utilizing simulated ground motions in performance-based engineering is validation to demonstrate that simulated ground motions can reliably capture features that have a significant effect on structural response. In particular, this paper deals with the use of ‘hybrid-broadband’ seismograms generated as part of the Southern California Earthquake Center (SCEC) CyberShake project, which combine waveforms that are generated by physics-based (deterministic) earthquake rupture simulations with a high frequency stochastic component. The goals of this paper are to (a) gauge the benefit, in terms of seismic demand estimation, of going from 0.5Hz to 1.0Hz deterministic simulation, (b) to help establish significance of high-frequency ground motion components for response of tall buildings, and (c) provide recommendations regarding the utilization of CyberShake simulated motions for risk and loss assessments. To this end, we analyze archetype buildings of different heights using suites of unscaled CyberShake motions generated for a site in downtown Los Angeles. Multiple stripes analysis is performed for corresponding sets of deterministic and broadband motions for the 0.5Hz and 1.0Hz CyberShake simulations. The results suggest that utilization of simulated motions for estimation of drifts and collapse risk is a promising area; conversely, several issues are noted for estimation of floor accelerations casting doubt for reliable use of CyberShake simulations in loss assessment studies given the current frequency limit of the deterministic simulation.

Citation
Bijelic, N., Lin, T., & Deierlein, G. (2018). Influence of high-frequency components of hybrid-broadband and deterministic CyberShake ground motion simulations on nonlinear response analyses of buildings. Seismological Research Letters, (under review).

Related Projects & Working Groups
Ground Motion Simulation Validation (GMSV) Technical Activity Group (TAG), Earthquake Engineering Implementation Interface (EEII)