Toward Response-Informed Validation of Physics-Based Ground Motions for Nonlinear Structural Analysis

Sajan K C, Shun L. Myint Than, Chukwuebuka C. Nweke, & Sifat Muin

Submitted August 30, 2026, SCEC Contribution #15306, 2026 SCEC Annual Meeting Poster #TBD

Physics-based ground motion simulations are increasingly used in nonlinear response history analysis (NRHA) to supplement limited empirical records while preserving physically realistic rupture, path, and site effects. However, application specific validation approaches for assessing simulated motions based on structural response remain limited. This study presents a response-based validation framework, or validation gauntlet, for evaluating physics-based simulated ground motions for NRHA applications using observed structural response as a benchmark.

An instrumented four-story steel moment-resisting frame office building in the San Francisco Bay Area that recorded basement and floor motions during the 1989 Mw 6.9 Loma Prieta earthquake is used as a case study. A calibrated nonlinear OpenSees model is subjected to recorded motions, regional physics-based simulations from the PEER–LBNL Ground Motion Simulation Database, and event specific Loma Prieta simulations. Multiple structural-response and waveform-based validation metrics, including inter-story drift ratios, floor accelerations, spectral compatibility, and response variability across stations and rupture realizations, are evaluated.

Results show that agreement in peak ground acceleration alone does not ensure realistic structural response prediction because PGA does not capture the period-dependent spectral characteristics that govern structural behavior. Instead spectral compatibility near dominant structural periods more strongly governs response realism and variability. The findings support the use of structural-response-based validation metrics for evaluating and selecting physics-based simulated ground motions for nonlinear structural analysis and future response-informed ground motion selection procedures.

Key Words
Physics-based ground motion simulations, nonlinear response history analysis, Structural Validation, OpenSees

Citation
K C, S., Myint Than, S. L., Nweke, C. C., & Muin, S. (2026, 08). Toward Response-Informed Validation of Physics-Based Ground Motions for Nonlinear Structural Analysis. Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motions (GM)