SCEC Award Number 12130 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Development of Analytical Tools for Engineering Validation of Simulated Ground Motions
Investigator(s)
Name Organization
Farzin Zareian University of California, Irvine
Other Participants Nicolas Luco, U.S. Geological Survey, Golden, Colorado, USA
Jonathan P. Stewart, UCLA, Los Angeles, USA
Jack W. Baker, Stanford University, Stanford, USA
SCEC Priorities 6e SCEC Groups GMSV, EEII, Simulators
Report Due Date 03/15/2015 Date Report Submitted N/A
Project Abstract
 The study presented here is aimed at identifying if simulated ground motions can be used for quantifying response of structural systems in a code-type application. To that end, we have quantified the difference between the response of various structures to two sets of ground motions: 1) a set of ground motions selected from a population of recorded ground motions and scaled to a target spectrum, and 2) a set of ground motions selected from a population of simulated ground motions and scaled to the same target spectrum. Various combination of structures (4-story, 8-story, and 20-story Steel Special Moment-resisting Frames), number of ground motions in each set (7 and 40), target hazard level (Design-based Earthquake, and Maximum Considered Earthquake), and ground motion selection and scaling procedures (fitting to Uniform Hazard Spectrum, and fitting to Conditional Mean Spectrum) were used. The result of the study shows that simulated ground motions overestimate maximum interstory drift ratio for the 4-story and 8-story structures when ground motions are scaled to match Uniform Hazard Spectrum; the difference is larger when sets consist of 7 motions compared to 40 motions are used. The reason for such difference can be found by comparing the pulse-like characteristics of ground motions in simulated and recorded ground motion populations. It appears that simulated motions have a higher proportion of pulse-like motions with substantial difference in pulse period compared to their recorded motion counterparts. Caution is warranted when extrapolating the result of this study given the limited number of SMRF models used. Nevertheless, ground motions were all from historic events where simulations have a high likelihood in matching the recordings.
Intellectual Merit This research aims at validating ground motion simulation models, and hence improving our confidence in such models, by identifying if simulated ground motions can be used for quantifying response of structural systems in a code-type application. The proposed validation effort takes advantage of current state-of-knowledge in structural response assessment to earthquake excitation.
Broader Impacts Current ground motion simulation models are physics-based and have the advantage of representing fault rupture processes, wave propagation, and site response characterization. The main point of this research is to validate these models and make their future application more reliable. The impact of this research is quite significant across a wide range of Earthquake Engineering concerns and can lead to betterment of resilience of buildings during hazards such as earthquakes.
Exemplary Figure Figure 4
Scatter plot of energy ratio vs. PGV ratio indicating the pulse-like nature of ground motions in selected sets.