青岛海湾大桥地震作用下的车桥动力响应研究

针对桥梁因车辆振动引起的疲劳开裂导致刚度下降而下挠增加等问题,本文以青岛海湾大桥大沽河桥段为例,运用振型叠加法对桥梁有限元模型进行时程分析,计算在地震作用下车桥系统的动力响应。结果表明,考虑地震作用时,位移时程曲线波动性较明显,且位移相对较大。考虑地震波后的加速度时程曲线比未考虑地震波时的波动性大,且加速度明显增加,可见地震波对车桥系统的动力响应影响很大,考虑地震波时的时程曲线波动性较不考虑地震波时明显;考虑地震波的作用后,随着速度的增加,桥梁的动挠度明显减小,这是因为车辆速度较小时,车辆在桥梁上的作用时间变长,同时车辆与地震共同作用的时间变长,在地震波的持续影响下,桥梁的动挠度增加;随着车辆数目的增加,桥梁的动力响应随之增大。该研究对青岛海湾大桥的抗震设计有重要的理论意义。

Dynamic Responses of Qingdao Bay Bridge under Earthquake Action

In order to study the problem that bridge fatigue cracking caused by vehicle vibration leads to the decrease of the stiffness and the increase of deflection,modal superposition method is used for the time history analysis of the bridge finite element model to analyze the dynamic response of the vehicle-bridge system of Qingdao Bay Bridge Dagu River section.The results are as follows.Considering the seismic action,the volatility of displacement time history curve is obvious,and the displacement is relatively larger; the volatility of acceleration time history curve considering the seismic action is larger than that not considering,and the acceleration increases obviously.Therefore,seismic wave has a great influence on dynamic response of the vehicle-bridge system,that the volatility of time history curve is more obvious when considering seismic action.Considering the effect of seismic waves,dynamic deflection of bridge decreases greatly with the increase of speed.This is because when the vehicle speed is slower,the time vehicles on bridge is longer,then the time vehicles on bridge with earthquake together is longer.Under the continuous effects of seismic waves,dynamic deflection of the bridge increases.With the increase of vehicle number,dynamic response of bridge is growing.By the research of dynamic response of Qingdao Bay Bridge,this study has important theoretical meanings for the seismic design of Qingdao Bay Bridge,and lays a good groundwork for the later dynamic study of bridge.