3-dimension Dynamic Analysis Of Isolation Bridge And Dynamic Testing

In recent earthquake accidents, some isolation bridges have experienced the shock and indicated their smart seismic resistant ability. And now, Isolation Bridge has been an important protection system for bridges. The further research on Isolation Bridge's dynamic character is necessary. Based on the prevenient study, this paper develops the 2-dimension research on Isolation Bridge to 3-dimension, for consummating the research field of isolation. The Xi'hu isolation bridge with the common shock and long-term pulse shock is analyzed by time history method. The shock excitation mechanism is researched. The Sequential Quadratic Program (SQP) is used for the optimization design of isolation. The isolation bridge's dynamic characters experimentation is made by sudden loading method. The main research is shown below:Considering the bi-direction interaction of Lead Rubber Bearing (LRB), kinematic hardening model is used for modeling the 3-dimension mechanism relation of LRB. The 3-dimension analysis FEM program for Isolation Bridge is made; the optimization program is made, which combines FEM program and SQP. So the optimal design of Isolation Bridge is realized by the optimization program, which can prevent the random choice of LRBResearches are made on the 3-dimension earthquake responses of isolation bridge suffered from common earthquake shock. This kind of response is very complicated because of 3-Dimension earthquake shock with the combination of horizontal and torsion responses. The results show that the earthquake response is lowered efficiently when isolation technology is adopted; there are great differences between the long-term pulse shock and the common shock in the bridge's seismic response; the advantage of isolation technology is not very clear, when the isolation bridge excited with the long-term pulse shock, even with large displacements. Therefore, enough consideration should be paid to the effect on Isolation Bridge of the long-term pulse shock while isolation technology is used near faultage. Otherwise, the collisions between beams or the drop of beams will easily occur.Isolation Bridge can be nearly regarded as linear because strong non-linear of isolation bearings suffered from common shock doesn't work. Interference of spacevibration doesn't exist because of separate vibration in every direction at the situation. The vibration of bridge suffered from sever shock is very complicated since the vibration of beams is not centered the bearings but offsets along and cross the bridge. So sufficient consideration must be placed on the space vibration when aseismic calculation is made, otherwise the design of structure would be not safe.The vertical accelerations at the top of piers are almost near the excitation, but the accelerations of beams change at great ranges which will cause the change of vertical pressures affecting ductility and yield loads of piers. So it should be studied in the future on how to reduce (or control) the vertical accelerations of beams.Optimization is carried out on the isolation design of bridge by the optimization program. Results can be used to long-term pulse shock and common shock. Seismic absorption ratio can be further improved. It is necessary to made optimization on the isolation design of bridge.The dynamic experimentations with little displacements are done on the isolation bridge by sudden loading method. The experimental results are close to the results achieved by the program.