Department: Structural Engineering
Scott Ashford | Jose Restrepo
Name: Azadeh Bozorgzadeh
Email: abozorgz @ ucsd.edu
Grad Year: 2007
Bridge abutments play an important role in the magnitude of earthquake-induced forces transmitted into the bridge structure. Many factors such as nonlinear soil behavior, soil properties, failure mechanism, and abutment dimensions must be considered for realistic characterization of abutment-backfill interaction. However, for simplicity, in many existing models for abutment capacity and stiffness, the effects of soil properties are not considered. The main goals of this research program are to determine the abutment capacity and stiffness from field tests, using different soil types and to develop a simplified soil dependent model to predict abutment behavior. In the first phase of the experiment, a diaphragm abutment (without a foundation) was built at 50% scale of a prototype abutment, to study the longitudinal stiffness and strength of a backwall. Four tests have been done in this phase. Two different soil types were used to characterize the range of soil properties to be expected behind bridge abutments. The second phase of this research program investigated the stiffness and strength of a seat type abutment. The reasonable agreement between calculated and measured values shows that the Log Spiral Theory provides an adequate means of estimating passive resistance of the abutment wall. The nonlinear variation of passive resistance of the backwall with deflection can be approximated by a hyperbolic-exponential curve that incorporates the initial elastic stiffness, the ultimate and residual passive resistance.
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