Analysis On The Response Of Bridge Collision Under Earthquake And The Performance Evaluation Of Buffer Device

The thesis was an ingredient of the project of "Shaanxi Provincial Science and Technology Research and Development Scheme".Passing through the investigation of the earthquake damage in bridge structures after Wenchuan earthquake, it can be shown that, the collision of bridge structure is the main factor that aroused the crushing of concrete in beam-ends, the damage of expansion joint and the collapse which was caused by oversize movement of the beam. Therefore, to analyzing the performance of the buffer device that to reduce the impact response of bridge structures as the target has important use value in engineering project.This thesis to take a 20m freely supported beam and a 3×20m continuous bridge in Shaanxi province as the background, and using the finite element method to simulate the colliding process of the structure in effect of earthquake power. Analyze the process of collide response and the factor that affect the collide response. And moreover, evaluating the performance of two kind cushion material that was in common used. Then aggregate analyzing the colliding response by adjusting the size of the gap which was kept in advance and the height of the bridge pier.It can be shown through the analysis results that, in regard to freely supported beam and continuous bridge, collide action enlarged the earthquake response of the structure, and emerged prodigious impact force.When the value of the gap of expansion joint and the rigidity of collided element, the value of the structure's impact force and the displacement of the main beam will be increased as the value of the gap of expansion joint and the rigidity of collided element increased. The behavior of the collision is not only concern with the inherent characteristic of the structure, but also depends on the earthquake waves imported and the condition of the ground. When the buffer device was set in the gap of the beam, the earthquake response of the structure was reduced effectively, but the effect in alleviating the collide response was different by different cushion material.When the beam-ends was obligate a gap, the value of the impact force and the displacement of the main beam will be reduced as the value of the gap of expansion joint and the rigidity of collided element decreased. When the gap was close-grained filled up, the value of the structure's impact force and the displacement will be smaller than the condition with gap, and the effect of the buffer reach to the best. Therefore, when the buffer device was installing, it was suggested to close-grained filled. When the beam bridge was installed with buffer device, the substructure will play leading role along with the increased of the height of the bridge pier. Simultaneously,the value of the impact force and the displacement of the freely supported beam and continuous bridge will increase with it, but the value of the continuous bridge will decrease, and after the gap was filled with buffer material of rubber, the collision can be effectively avoid.It can be shown through the analysis of the collision response about the freely supported beam and continuous beam, in condition with both of them were set buffer device and another condition of both of them were set nothing, that the instill of the buffer device can effectively reduce the adverse effect caused by collision. The research production can consult for the design of seismic isolation and reduction, also it can provide technical support for appraisal of the earthquake damage in bridge.