| Summary: | 碩士 === 國立中央大學 === 土木工程學系 === 103 === In recent years, the earthquake caused many disasters in the world. Many countries must be use the isolation system in seismic design. By prolonging the structural period to reduce the seismic force is better than traditional design. From researches we can see that the rocking response of spread foundation is a unique isolation system. After earthquakes, the rocking mechanism of spread foundation can reduce the seismic force of the main structure, besides it can extend the period of structure and decrease the seismic force. In addition, the soil will generate the plastic behavior and absorb the seismic energy under the extreme earthquake.
This study aims to place the nonlinear soil spring to the 3D-VFIFE calculation process. Modeling soil and foundation interaction system to verify the correctness of the nonlinear soil spring, and simulate the bridge’s extreme behavior in the earthquake.
3D Vector Form Intrinsic Finite Element, a new computational method is adopted in this study because the VFIFE has the superior in managing the engineering problems with material nonlinearity, discontinuity, large deformation and arbitrary rigid body motions of deformable bodies. In order to simulate the interaction between soil and foundation, the study reference UC Berkeley team’s soil spring (Beam-on-Nonlinear-Winkler Foundation). This model can simulate the vertical soil (q-z spring), lateral passive soil (p-x & p-y spring) and the friction force between soil and foundation (t-x & t-y spring). Through numerical simulation of examples to verify the soil element model are feasible and accurate. Finally, five-span continuous bridge as a model to investigate the effect of the parameter changes, and to understand the bridge behavior in ultimate condition.
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