下承式钢箱系杆拱桥在多车荷载作用下的动力响应分析

Dynamic Response Analysis of Steel Box Tied-arch Bridge under Multi-vehicle Loading

目的研究钢箱系杆拱桥车桥耦合振动响应并分析多车荷载对该类型桥梁车桥耦合振动的影响。方法以舍里甲大桥为工程背景,基于ANSYS软件建立该桥的有限元模型,并将3轴汽车简化为三维9自由度车辆模型;结合模态综合法,采用Newmark-β数值方法计算得到桥梁的位移及其动力放大系数。结果车辆偏载对主梁竖向挠度冲击系数的影响较小;多车荷载对桥梁动力响应具有较大影响,主梁竖向挠度冲击系数随横向加载车辆数量的增加而减小,横向双车、横向三车对比横向单车冲击系数分别减小33.98%和43.32%;随纵向加载车辆数量的增多出现较大波动,纵向多车工况下冲击系数小于单车工况,纵向双车、纵向三车的冲击系数分别比纵向单车减小26.39%和18.06%;两车开对比两车同向行驶的主梁挠度冲击系数减小了51.40%;桥梁部分构件的局部动力冲击系数大于桥梁整体动力冲击系数,其中短吊杆的动力冲击系数相比于长吊杆增大72.5%。结论多车荷载作用下的主梁竖向挠度冲击系数均小于单车荷载作用,按单车荷载作用下冲击系数计算汽车荷载效应是较为安全的。

The purpose of this paper is to study the influence of multi-vehicle load on the vehicle bridge coupling vibration response of steel box tied arch bridge.Taking Shelijia bridge as the engineering background,the finite element model of the bridge was established based on ANSYS software,and the 3-axis vehicle was simplified to a 3-D 9-DOF vehicle model.Combined with the mode synthesis method,Newmark-βnumerical method was used to calculate the displacement and dynamic amplification factor of the bridge.The impact factor of the vertical deflection of the main beam is less affected by the vehicle eccentric load;the dynamic response of the bridge is greatly affected by the multi-vehicle load.The impact factor of the vertical deflection of the main beam decreases with the increase in numbers of the transverse loading vehicles,the impact factor of two vehicle and three vehicle decreases by 33.98%and 43.32%respectively compared with that of single vehicle,and fluctuated with the increase in numbers of the longitudinal loading vehicles,the impact factor of longitudinal multi vehicle condition is smaller than that of single vehicle,and the impact factor of longitudinal two vehicle and longitudinal three vehicle is 26.39%and 18.06%lower than that of single vehicle.The deflection impact factor of the main beam with two cars opposite running is 51.40%lower than that of the main beam running in the same direction.The local dynamic impact factor of some components of the bridge is greater than the overall dynamic impact factor of the bridge,and the dynamic impact factor of the short hanger is 72.5%higher than that of long hanger.Conclusion:the impact factor of the vertical deflection of the main beam under multi-vehicle load is less than that of the single vehicle load.It is safe to calculate the vehicle load effect according to the impact factor under the single vehicle load.