MPC Research Reports
Report Details

Title:	Calibrating Ground Response Analyses Beneath an Instrumented Bridge using the I-15 Borehole Array and Ground Motions from the 2020 M5.7 Magna Earthquake
Authors:	Brady Cox, Tyler Jackson, and Nishkarsha Dawadi
University:	Utah State University
Publication Date:	Mar 2024
Report #:	MPC-24-517
Project #:	MPC-694
TRID #:	01920233
Keywords:	boreholes, bridges, calibration, earthquakes, numerical analysis, seismicity, S waves

Abstract

The I-15 Downhole Array (I15DA) is located near the intersection of I-15 and I-80 in Salt Lake City, Utah. This downhole array is installed in soft soil deposited by Lake Bonneville, where depth to bedrock is expected to be at a considerable depth. The soil conditions at the I15DA are representative of other sites in deep, sediment-filled valleys throughout the state (e.g., the Utah, Salt Lake, and Cache valleys), and understanding the seismic response at the downhole array is crucial to determine how to conduct numerical site response analyses at other locations across the state. The I15DA recorded a number of aftershocks following the 2020 M5.7 Magna Earthquake, and these ground motion records have been used to calibrate numerical site response analyses. This report details single- and multi-dimensional site response studies aimed at calculating theoretical transfer functions that capture the empirical transfer functions produced by small-strain ground motions recorded by horizontal components of sensors in the I15DA. We investigate the importance of accounting for spatial variability in shear wave velocity (Vs) during site response modeling using Vs obtained from invasive methods, non-invasive methods (i.e., surface wave inversion-derived Vs profiles), and a pseudo-3D Vs model developed using the H/V geostatistical approach.

How to Cite

Cox, Brady, Tyler Jackson, and Nishkarsha Dawadi. Calibrating Ground Response Analyses Beneath an Instrumented Bridge using the I-15 Borehole Array and Ground Motions from the 2020 M5.7 Magna Earthquake, MPC-24-517. North Dakota State University - Upper Great Plains Transportation Institute, Fargo: Mountain-Plains Consortium, 2024.