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Effect of Soil Nonlinearity on Physics-Based Ground Motion Simulations

Description: 

Nonlinearity can dramatically affect soil behavior, especially for the soft soils within the shallow crust and under complex cyclic loadings induced by strong earthquakes. In the past few decades, numerous constitutive models of soils have been developed and applied to the analysis of soils and soil-structure systems. However, few physics-based ground motion simulations consider soil nonlinearity, mainly due to a significant increase in computational cost when nonlinearity is included and a lack of data to calibrate a constitutive model for a large region. In this study, we adopted a 3D bounding surface plasticity model, calibrated it using stiffness degradation (G/G_max) curves for multiple geology formations, and performed a large-scale broadband (up to 8 Hz) fully nonlinear physics-based ground motion simulation for a district in Istanbul, Turkey. In addition, by utilizing the simulated ground motions, we conducted one-dimensional nonlinear site response analyses (SRA) for a total of 2912 sites. For each site, we compared the time histories and surface shaking intensities, such as PGA, PGV and spectral accelerations, between linear and nonlinear 3D simulations, 1D nonlinear SRAs and an empirical ground motion model. Results indicate that soil nonlinearity can both significantly amplify and slightly de-amplify site responses, depending on the soil parameters (e.g., Vs30, G/G_max curves, bedrock depth) of the sites.

Session: Physics-Based Ground Motion Modeling - I

Type: Oral

Date: 5/3/2024

Presentation Time: 08:30 AM (local time)

Presenting Author: Wenyang

Student Presenter: No

Invited Presentation: 

Authors