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Room: Ballroom

Date: 4/20/2023

Session Time: 8:00 AM to 5:45 PM (local time)

Ground Truthing Multidimensional Site Response Analyses at Borehole Array Sites
A significant amount of seismic site response research over the past decade has focused on our abilities to replicate recorded ground motions at borehole array sites, where both the input (rock) and output (surface) ground motions are known. When viewed in aggregate, these studies have found that approximately 50% of borehole array sites are poorly modeled using 1D ground response analyses (GRAs). While multidimensional (i.e., 2D and 3D) GRAs are theoretically plausible, 1D GRAs remain by far the most widely used approach for simulating site effects in practice and research. This is partly due to a lack of well-documented and openly accessible case histories that ground truth multidimensional GRAs at borehole array sites. The availability of multidimensional GRA validation studies at borehole array sites could serve as a benchmark for practitioners and researchers to calibrate their own analyses and achieve more reliable seismic hazard assessment and risk mitigation.

A current research study is being conducted with collaborators from research and industry to ground truth multidimensional GRAs at the Treasure Island Downhole Array (TIDA). A large-scale, site-specific 3D subsurface model is now available for this site and multidimensional GRAs have proven that site response recorded in the borehole array is influenced by subsurface spatial variability at distances over 1 km away. Several teams have performed multidimensional GRAs for the TIDA site using different commercial and open-source software (e.g., OpenSees, Sesimo-VLab, FLAC, LS-DYNA). We strongly encourage contributions from the different collaborators on this project, as well as from other studies on any aspect of ground truthing multidimensional GRAs. This session will provide an opportunity for researchers and engineers to discuss and constructively compare modeling strategies, boundary conditions, computational time and ground truthing of the numerical results against recorded ground motions.

Conveners
Mohamad M. Hallal, University of California, Berkeley (mhallal@utexas.edu)
Brady R. Cox, Utah State University (brady.cox@usu.edu)

Poster Presentations