Period-dependent duration of earthquake ground motions in sedimentary basins and their effects on structural collapse risk

Nenad Bijelic, Ting Lin, & Gregory Deierlein

Under Review 2018, SCEC Contribution #8041

Presence of sedimentary basins is well recognized for potential detrimental effects on buildings, but their quantification has remained largely elusive due to limited availability of recorded motions. This paper tackles the issue of the influence of basin effects present in ground motions in deep sedimentary basins on seismic collapse risk through the use of physics-based ground motion simulations. Deaggregation of collapse risk obtained using direct analysis of around 500,000 site-specific ground motions generated as part of the Southern California Earthquake Center’s (SCEC) CyberShake project is first used to gain insight into properties of ground motions driving collapse at a deep basin site in the Los Angeles basin. Different ground motion archetypes are formulated based on waveform properties of the basin ground motions. To isolate the influence of basin effects on collapse response, spectrum and duration equivalent sets of basin and non-basin motions are developed and used to perform incremental dynamic analysis (IDA) of three structures with different dynamic properties. Depending on the fundamental period of the structure, it is found that basin motions can be more damaging causing significantly different collapse response. Since the basin and non-basin sets used to perform IDA are nominally equivalent in terms of conventionally used Sa and significant duration intensity measures (IMs), novel IMs – termed duration and sustained amplitude adjusted response spectra – are used to contrast the properties of motions. These IMs show that motions in the basin set have higher sustained amplitudes and longer durations in the period range of around 1.5s and longer.

Citation
Bijelic, N., Lin, T., & Deierlein, G. (2018). Period-dependent duration of earthquake ground motions in sedimentary basins and their effects on structural collapse risk. Earthquake Spectra, (under review).


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