The Study on Seismic Behavior of Scoured Bridge with Pile Foundation
Date Issued
2014
Date
2014
Author(s)
Wang, Shiou-Chun
Abstract
This dissertation presents a study on the seismic performance and soil-structure interaction (SSI) of a scoured bridge models with pile foundation by shaking table tests using a laminar shear box. The model bridge with pile foundation comprised a lumped mass representing the superstructure, a steel pier, and a footing supported by a single aluminum pile within dry soil and saturated soil. The end of the pile was fixed at the bottom of the shear box to simulate the scenario that the pile was embedded in a firm stratum of rock. The model bridge was subjected to one directional shakes, including white noise, sinusoidal accelerations and earthquake ground motions. A three-dimensional finite element model was created using the ANSYS program to simulate the shaking table tests. The soil dynamic property was taken into consideration for the nonlinearity of the soil-pile interface, and an equivalent linear model was used to capture the soil behavior. The computational model was validated by comparing the results of the finite element analyses with the data obtained from the shaking table tests. The performance of the model bridge with pile foundation was discussed for different scoured conditions. A numerical modeling procedure has been proposed to evaluate the time history response for the seismic behavior of the soil-bridge-foundation interaction system under earthquake excitations. It is found that the moment demand of pile increases with the increase of scoured depth, whereas the moment demand of the bridge pier decreases, and this transition may induce the transformation of bridge failure mechanism from pier to pile. Thus, the seismic demand on scoured pile foundations may be underestimated and misinterpreted to a certain degree. When evaluating the system damping ratio with SSI, the system response may not be significantly changed even if the soil viscous damping contribution is varied.
Subjects
scour effect
seismic performance
soil-structure interaction
multi-hazard
shaking table
finite element method
Type
thesis
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