Vehicle Braking Force Floating System For Bridge Vibration Control

Floating system bridge can dissipate the vibration energy by the longitudinal oscillation of the girder. However, because of non-restraint in longitudinal direction, the excess longitudinal displacement caused by dynamic external loads may lead to the damage of connecting component, even the girder falling, so appropriate control measures should be taken to reduce the excess longitudinal displacement. By taken Pingsheng Bridge as an engineering background, the longitudinal vibration response of floating system bridge under vehicle braking force and corresponding control measures are analyzed in this paper, and the main contents are as follows:(1) Based on the vehicle investigation and classification methods, the composition of vehicle types on Pingsheng Bridge is developed, and the time-history curves of braking force of different vehicle types are obtained by the existing experimental data. Then the vehicle braking force model of Pingsheng Bridge is established.(2) The finite element model of Pingsheng bridge is established with the MIDAS software, and the longitudinal vibration responses under vehicle braking forces are analyzed. The results indicate that longitudinal displacements of the end of the girder and the top of the tower are relatively large and appropriate control measures are necessary.(3) Viscous damper parameters of vibration reduction are optimized by using the influence matrix method. The effects of vibration reduction caused by the optimal viscous damper and the change of damper numbers are analyzed. The results verify that good control effects could be achieved by optimal viscous damper, and the values of longitudinal displacements of the end of the girder and the top of the tower decrease gradually as the number of the damper increasing. Besides, the internal forces are controlled effectively.(4) Friction pendulum bearing parameters of vibration reduction are optimized by the orthogonal test method, then the effects of vibration reduction of the optimal parameter are analyzed, including the condition of changes in numbers. The results show that better control effects could be achieved by friction pendulum bearings, and the value of longitudinal displacement response of the girder reduces 28.22%.(5) The effects of vibration reduction of the combination with viscous dampers and friction pendulum bearings are analyzed, and the results indicate that the effects of the combination is better than the above-mentioned two measurements. The value of longitudinal displacement response of the girder reduces 42.17%.