Numerical Modeling of Soil-Shaft Interaction Validated Using the Instrumented Hayward Bridge in California

Finite element methods can be used to analyze the dynamic responses of soil-foundation-structural systems during earthquakes. Therefore, the validation of finite element models with actual seismic recordings is required to benefit from their use in foundation seismic design. In this paper, the acceleration records from the Hayward-I580/238 bridge in California will be studied. At the HaywardI580/238 bridge, three-component accelerometer recordings from two geotechnical downhole arrays at the surface and depths down to 90 meters were used. Furthermore, from 2011 through 2022, 15 earthquakes were recorded at these downhole arrays ranging from Mw 3.4 to Mw 6. However, this paper focuses on the earthquake events within the range of Mw 3.4 to Mw 4.4. Therefore, this study is limited to earthquakes up to Mw 4.4. In the first part of this study, a free-field model of the Hayward-I580/238 bridge site is built using the OpenSees software. Then, in the second part, a drilled shaft of the HaywardI580/238 bridge is modeled. A comparison of the dynamic responses generated by OpenSees with the recorded data from the geotechnical downhole arrays will be used to validate the free-field model, and the acceleration responses from the free-field model will be applied to the drilled shaft. Then, the behavior of the drilled shaft under the applied seismic forces in terms of different calculated parameters (e.g., displacements, reaction forces, etc.) will be investigated. As a result of this study, despite the absence of actual acceleration recordings, obtaining the responses of the soil layers in various depths is possible using a numerical modeling method. In conclusion, not only OpenSees provides a tool for monitoring drilled shaft behavior during seismic events, it provides a robust tool for future drilled-shafts seismic designs.