Characterization of basin effects for seismic performance assessments of tall buildings using CyberShake simulations

Ting Lin, Nenad Bijelic, & Gregory Deierlein

Submitted August 15, 2017, SCEC Contribution #7734, 2017 SCEC Annual Meeting Poster #241 (PDF)

To explore where simulated ground motions provide unique advantages over recorded motions for performance-based engineering, this work focuses on basin effect characterization in seismic hazard and risk assessments of tall buildings. Basin effects are among the most prominent features of ground motions that can be more reliably captured by 3D physics-based earthquake simulations as compared to empirical methods using ground motion prediction equations (GMPEs). We conduct (1) direct analysis with around one million nonlinear response analyses using simulated seismograms and physics-based probabilistic seismic hazard analysis (PSHA) from CyberShake simulations, in contrast to (2) performance assessment with conventional methods using recorded motions from PEER NGA database and PSHA from US Geological Survey. In terms of tall building seismic demands, the two approaches yield similar estimates for Los Angeles downtown, LADT, where many tall buildings are located, but produce drastically different results for a deep basin site, STNI. Further investigation of direct analysis using CyberShake simulations enables deaggregation of building collapse risk to examine (a) relative contributions of earthquake ruptures and (b) waveform properties of damaging motions. Based on these insights, ground motion archetypes are formulated to represent long-period cyclic features. To gauge the effect of unique archetype features on structural response, we develop spectrum- and duration-equivalent sets of “basin” and “non-basin” ground motions to compare collapse fragility. Finally, we propose a novel metric - termed duration and sustained amplitude adjusted response spectra - to characterize damaging features of basin motions that contribute to collapse.

Key Words
ground motions, tall buildings, seismic hazard, collapse risk, basin, CyberShake

Citation
Lin, T., Bijelic, N., & Deierlein, G. (2017, 08). Characterization of basin effects for seismic performance assessments of tall buildings using CyberShake simulations. Poster Presentation at 2017 SCEC Annual Meeting.


Related Projects & Working Groups
Earthquake Engineering Implementation Interface (EEII)