动水压力对连续刚构桥梁地震响应的影响

为了研究地震作用下深水薄壁空心桥墩内外域水体动水压力对连续刚构桥梁动力响应的影响,应用流固耦合有限元理论,考虑重力、纵向预应力和动水压力,建立了庙子坪岷江大桥连续刚构桥梁的计算模型,并采用实测的地震波进行计算.结果表明:动水压力对连续刚构桥梁自振频率和振型的影响不大,前30阶频率降低率最大值约为8％,箱梁各部分横向位移峰值增量在10％～20％之间,主墩内力峰值增量最大值约170％,箱梁内力峰值增量最大值约75％；地震加速度、桥墩入水深度是影响动水压力的重要因素.

Effects of Hydrodynamic Pressure on Seismic Response of Continuous Rigid-Framed Bridge

The hydrodynamic pressure caused by inner water and outer water of thin-walled hollow piers under earthquake has an effect on the dynamic response of continuous rigid-framed bridges.In order to investigate the effect,a calculation model for the continuous rigid-framed part of Miaoziping Minjiang bridge,which is based on the finite element theory of fluid structure-interaction,was built by using ANSYS Fluid30 element to simulate water.The seismic response of the bridge was calculated by taking into account the gravity,longitudinal prestress,hydrodynamic pressure,and earthquake waves recorded by the nearest seismic station.The results show that hydrodynamic pressure has little influence on natural frequencies and mode shapes of the continuous rigid-framed bridge,and the maximum reduction rate of the first 30 natural frequencies is approximately 8%,increments of transverse displacement peaks of the box girder reach 10%-20%,the maximum increment of internal force peaks of the main piers reaches 170%,and this value is about 75% for the box girder;and,the earthquake wave acceleration and water depth are the important factors influencing the hydrodynamic pressure.