利用桥墩动力响应反推输入激励的模型试验研究

摘要

针对在撞击荷载作用下的车桥耦合振动分析中输入激励难以直接采集的情况,基于模型试验提出利用桥墩动力响应反推输入激励(撞击力时程)的方法.利用车轨桥耦合试验平台对一座下承式铁路钢桁拱桥模型进行试验,通过刚性模型汽车撞击桥墩,测试桥墩底部的动应变,反推撞击部位的撞击力时程.将所获得的撞击力时程与力传感器直接采集的撞击力时程进行比较,结果表明二者匹配良好,且实测的桥墩一阶振动频率与有限元模拟结果吻合,验证了该方法的可行性.建议将1.2倍的计算力时程作为实际应用的撞击力时程.%As it is difficult to directly acquire the pier input excitation under the action of colliding load in the train and bridge coupling vibration analysis,a method for reversely deriving the input excitation (the colliding force time history) from the pier dynamic responses based on the model test was proposed.The train,track and bridge coupling vibration test platform was used to carry out the test of a railway through steel truss arch bridge model.By way of colliding against the pier of the model,using the rigid model truck,the dynamic strain of the footing of the pier was measured and the colliding force time history of the collided part of the pier was reversely derived.The derived colliding force time history was then compared to the colliding force time history directly acquired by the force sensors.The results show that the two kinds of the colliding force time history match well and the measured first order vibration frequency of the pier is also consistent with the first order vibration frequency of the finite element simulation,verifying that the method proposed in this paper is feasible.It is herewith advised that the 1.2 times of the calculated force time history should be used as the colliding force time history in the practical application.