基于随机车流的钢桁梁悬索桥振动响应分析

Vibration Response Analysis of Steel Truss Girder Suspension Bridge Based on Random Traffic Flow

文中以金安金沙江大桥为研究对象,基于蒙特卡洛法在Matlab中随机抽样建立了包含车型、车道、车距、车速、车重五种相关参数的随机车流模型,并采用midas-Civil建模求解大跨度钢桁梁悬索桥在随机车流荷载作用下的振动响应.结果表明:悬索桥的车致振动响应随着车流密度的增大而增大,其增加幅度呈现非线性特征;加劲梁1/4跨至3/8跨的附近区域位移最大;吊杆应力从1/2跨向梁端两侧不断增大,梁端部附近区域的吊杆应力最大;下弦杆在端部轴力响应最小,其余各处下弦杆轴力最大值的变化趋势较为平稳;华坪侧桥塔位移值比丽江侧位移值大,车流状况与桥塔高度对桥塔位移的影响存在相关性.

Taking Jin’an Jinsha River Bridge as the research object,based on Monte Carlo method and random sampling in Matlab,a random traffic flow model including five related parameters,such as vehicle type,lane,vehicle distance,vehicle speed and vehicle weight,was established.Midas/Civil modeling was used to solve the vibration response of long-span steel truss suspension bridge under random traffic load.The results show that the vehicle-induced vibration response of suspension bridge increases with the increase of traffic density,and its increasing amplitude presents nonlinear characteristics.The displacement of stiffened beam is the largest in the vicinity of 1/4 span to 3/8 span.The stress of suspenders increases from 1/2 span to both sides of the beam end,and the stress of suspenders near the beam end is the highest.The axial force response of the bottom chord is the smallest at the end,and the change trend of the maximum axial force of the other bottom chords is relatively stable.The displacement value of Huaping side pylon is larger than that of Lijiang side pylon,and there is a correlation between traffic flow and the influence of pylon height on pylon displacement.