在役大跨径曲弦桁梁桥车桥耦合振动分析

Analysis of vehicle-bridge coupled vibration of long-span curved truss bridge in service

为研究在役曲弦桁梁桥的动力性能和车桥振动响应,基于考虑跳车脱空时段的车桥耦合振动分析方法,进行在役曲弦桁梁桥车桥耦合振动分析。以122 m跨径彩虹桥为计算示例,建立桥梁有限元模型,分析桥梁动力特性,并计算空间车队过桥动力响应,探讨车速、车辆数量、车队分布及路面不平度等因素对在役曲弦桁梁桥动力响应的影响。结果表明:桥面系竖向刚度相对较弱,桥面局部振动易被激发;桥面竖向振动及各动力响应随着汽车数量、布载车道数量增加而显著增大;桥梁下弦跨中位移冲击系数超过规范设计值,桥面振动程度较大;车辆中、后轮易发生跳车,路面等级越高,发生脱空次数越多,在路面等级良好状态下汽车也会出现跳车现象。

In order to study the dynamic performance and vehicle-bridge vibration responses of the curved-string truss bridge in service,the vehicle-bridge coupled vibration analysis of the curved-string truss bridge in service are carried out based on the vehiclebridge coupled vibration analysis method which can consider the period of vehicle jumping.The Rainbow Bridge with span of 122 m is taken as an example,the finite element model of the bridge is set up to analyze the dynamic characteristics of the bridge and the dynamic responses of the bridge are calculated while space motorcades cross the bridge,and then,the influences of factors such as speed,number of vehicles,motorcade distribution and road surface roughness on the dynamic responses of the curved-string truss bridge in service are discussed.The result shows that the vertical stiffness of the bridge deck is relatively weak,and the local vibration of the bridge deck is easy to be excited;the vertical vibration and the dynamic responses of the bridge deck increase significantly with the number of vehicles and the number of loaded lanes;the impact coefficient of mid-span displacement of the bottom chords exceed the value of design standard,and the bridge deck vibrates always with a greater degree;the middle and rear wheels of the vehicles are prone to jump,the higher the grade of road surface roughness is,the more jumps of vehicles will occur,and the vehicles are also prone to jump when the road surface roughness is in good conditions.