Finite Element Modeling Of The Dynamic Soil-Bridge Interaction

Dynamic soil-structure interaction (SSI) is the important factor for the design of the structure, and the key for the dynamic analysis of structure. The thesis mainly study the effects on SSI of different soil conditions, foundation shapes, and structure forms to discuss the suitable finite models for the dynamic analysis of cable-stayed bridge based on finite methods. This thesis addresses the following aspects:1. Based on the flexible foundation beam theory and substructure method, different soil conditions, foundation shapes, and structure forms that affect the dynamic stiffness and damp are discussed;2. The simplified soil-structure interaction models of the shallow foundation are investigated and compared, which include fixed model, six springs model and bathtub model, considering the base shear and the passive earth pressure of the shear wall, the bathtub model’s theoretical basis and calculation results are closer to the actual situation;3. The simplified soil-structure interaction models of the pile foundation are investigated and compared, which include the fixed model, the revised m model and bathtub model, the revised m model considers different condition of the soil layers, and has little effect on the rotational stiffness and damping;4. Use the improved models to analyze the dynamic response of the cable-stayed bridge. In the case studies, the pile cap and pile groups are considered simultaneously, the results of the dynamic analysis of a cable-stayed bridge shows:soil-structure interaction obviously affects the response of lower pylon column and main girder’s; the pile cap’s shape and stiffness have effects on the dynamic responses.