Research On Pounding Of Isolated Curved Girder Bridge

At the area of high protected earthquake intensity, the earthquake response of fixed pier can be reduced evidently by using the technology of vibration isolating. But the displacement of bridge girder will increase correspondingly when using the vibration isolating technology. So pounding between the adjacent girders will happen more easily. Especially for the pounding between girders of curved bridge, it is so complex that more attention should be paid on the problem. Before pounding research, an issue should be solved first, the least favourable earthquake excitation direction. At the present time, the main method for solving the least favourable earthquake excitation direction is spectrum mode superposition method. But there are no calculational methods of least favourable earthquake excitation direction in the nonlinear time history analysis. Here study on the pounding between adjacent girders of curved bridge will be addressed. The following issues are included.(1) Method, calculating least favourable earthquake excitation direction of isolated curved bridge, is confirmed firstly in the nonlinear time history analysis. Based on the analysis in ANSYS, calculational method of least favourable earthquake excitation direction is addressed in the dissertation. The ANSYS analysis indicates that the least favourable earthquake excitation direction of different responses is different. For isolated curved bridge, the least favourable earthquake excitation direction of an earthquake response is the same with the complexor direction of the response itself. And contrasted with the spectrum mode superposition method, we can get that the method confirmed in the dissertation is more accurate, simple and convenient.(2) Based on straight rod axial collision theory and rigid-body collision mode, the formulae, calculating the rigidity and damp of curved bridge collision division approximatively, are presented. Firstly, straight rod axial collision theory is addressed. Then according to the law of conservation of momentum and the law of conservation of energy, the approximative formulae calculating the rigidity and damp of curved bridge collision division are addressed.(3) Some influence factors, which are on the pounding between the girders of isolated curved bridge, are studied. There is mass ratio between adjacent girders, girder curvature, expansion joint distance, and period ratio between adjacent girders and so on. These factors are studied seriatim. And according to the analysis of results, we try to find out whether there is some common ground among the influence law, how these factors influence the pounding of isolated curved bridge. The research results indicate that these factors can be sum up to one influence factor, which is the period ratio.