地震与风联合作用下大跨桥梁车-桥耦合振动分析

为了研究大跨桥梁在风、车及地震联合作用下的动力响应,在已有风-车-桥耦合振动分析程序的基础上,利用大质量法模拟桥梁受到的地震作用,建立了地震-风-车-桥耦合振动分析的数值模拟平台,通过质量-弹簧-阻尼系统模拟车辆模型,利用有限元方法建立桥梁模型,采用谱表示法模拟路面粗糙度、风场和地震动,通过分离迭代方法求解地震-风-车...

Coupled Vibration Analysis of Vehicle-bridge for Long-span Bridge Under Wind and Earthquake Action

The present study proposes an earthquake-wind-vehicle-bridge analytical platform that aims to evaluate the dynamic characteristics of long-span bridges subjected to combined actions from wind,vehicles,and earthquakes.The earthquake-wind-vehicle-bridge analytical platform is developed based on the wind-vehicle-bridge numerical framework,in which the seismic load is simulated using the large mass method.Within the platform,the vehicle is modeled as a mass,spring and damping system,while the bridge model is established by the finite element method.The road roughness,wind field,and ground seismic motion are then simulated by the spectrum representation method.The coupled earthquake-wind-vehicle-bridge dynamic system is solved through a separate iterative method.For illustration,the Sutong Bridge with a main span of 1088m was analyzed using the proposed numerical platform.The dynamic responses of the vehicle-bridge system under combined wind and earthquake loads were evaluated.Additionally,the influence of the spatial variability of ground motion on the dynamic response of the vehiclebridge system was thoroughly evaluated.The results showed that for a bridge under operational wind and vehicle loads,abrupt seismic excitation could cause a significant increase in the dynamic response of the vehicle-bridge system and become the dominant dynamic factor of the earthquakewind-vehicle-bridge system.Compared with the bridge response of the earthquake-vehicle-bridge system,the additional presence of wind alongside traffic and earthquakes increases the lateral bridge responses,but suppresses the vertical bridge responses.In comparison with the dynamic response of the bridge,if an additional wind speed of 20m·s-1 is applied to the system,the extreme lateral displacement response of the bridge could increase by 40%.Therefore,the influence of the daily wind load on the dynamic response of the vehicle-bridge system cannot be ignored,even if the seismic load was dominant.After the occurrence of an earthquake,the maximum lateral acceleration of the vehicle is more than 0.5g,and the maximum vertical acceleration is approximately 1g,which may cause the vehicle to slide or roll;therefore,the operation behavior of the vehicle should be studied further.The results of the spatial variability of the ground motion show that not only the shape of the dynamic responses of the vehicle-bridge system shifts,but also the extreme value is altered after considering the spatial variability.The results suggest that it is of paramount importance to account for the spatial variability of the ground motion in the coupled earthquake-wind-vehicle-bridge dynamic analysis,to ensure the safety of the bridge as well as the moving vehicle.