SCEC Award Number 19114 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Critical assessment of probabilistic seismic demand analysis of ordinary bridge structures using Cybershake simulations
Investigator(s)
Name Organization
Farzin Zareian University of California, Irvine Sanaz Rezaeian United States Geological Survey
Other Participants
SCEC Priorities 4d, 4b, 4c SCEC Groups EEII, CXM, CEO
Report Due Date 04/30/2020 Date Report Submitted 11/07/2020
Project Abstract
 We evaluated CyberShake (ver 15.12) simulated ground motions using probabilistic seismic demand analysis of Ordinary Standard Bridges (OSBs). For five Southern California sites, catalogs of simulated ground motions representing a time-span of 200,000 years with diverse sites and local seismicity conditions were obtained from Cybershake (ver 15.12). Approximately 20,000 ground motions from events with Mw > 6.0 were collected for each site. These waveforms were applied to four OSB structures to calculate the bridge column drift ratio (CDR). A set of hazard-targetted scaled recorded ground motions are attained to conduct Incremental Dynamic Analysis (IDA) for all combinations of site and OSBs to obtain CDRs. The obtained IM-EDP relations were integrated with the ground motion Intensity Measure (IM) hazard curves to compute EDP hazard curves. The effect of uncertainty in the ground motion incidence angle with respect to bridge structures is incorporated by applying the ground motions at 10o increments and obtaining the median CDR termed as Rot50CDR. The estimated Rot50CDR at various return periods is used to build the empirical EDP hazard curves and compared against the EDP hazard curves obtained from NLTHA using the Cybershake’s simulated ground motions. The EDP hazard curves from the two methods are compared and sources of difference between the results are identified. The results show that CyberShake (ver. 15.12) simulation can be used for the seismic performance assessment of OSBs with short periods. Long-period OSBs tend to have larger EDPs once subjected to CyberShake (ver. 15.12) simulations as compared to the EDPs obtained using recorded ground motions.
Intellectual Merit The fundamental assumption that recordings from past world-wide earthquakes can be used for engineering of new structures in locations with different seismic characteristics has several limitations. Using simulated ground motions can overcome these limitations. Due to such advancements in simulations, much attention has been given to validation research in recent years. The study presented herein is a move in the direction of validating and utilizing simulated ground motions for bridge engineering practice.
Broader Impacts The project by nature has impacted the engineering community to utilize simulated ground motions in practice.
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