三线合一、三塔悬索桥风-车-桥耦合振动性能对比

Comparison of wind-vehicle-bridge coupling vibration characteristics for three-line three-tower suspension bridge

以某三线合一、三塔悬索桥的2种设计方案(钢箱桁和钢桁方案)为工程背景,通过车桥系统节段模型风洞试验,测试了车辆和桥梁的三分力系数,并基于风-车-桥系统空间耦合动力学模型,采用自主研发的桥梁分析软件BANSYS,对比分析了该桥的结构动力特性与风-车-桥耦合振动性能。分析结果表明:三线合一、三塔悬索桥结构自振频率较低;车辆气动力受轨道位置的影响较大,钢桁方案迎风侧车辆阻力系数约为钢箱桁方案的2.2倍;当风速为0时,桥梁、车辆的动力响应总体上是随车速的增大而增大,在同一车速下,钢桁方案的桥梁位移较钢箱桁方案大,主要是由于钢桁方案的桥梁整体刚度略弱于钢箱桁方案;当考虑风速影响时,桥梁的横向响应随风速的增大而显著增大;车辆位于迎风侧,风速为25m·s^(-1)时,钢箱桁方案和钢桁方案的桥梁横向位移约分别为风速为15m·s^(-1)时的位移的2.4倍和3.8倍,横风对桥梁的横向响应起主导作用;同一风速时钢桁方案的桥梁响应总体上较钢箱桁方案大;同一方案时车辆响应随风速的增大而增大,当风速达到25m·s^(-1)时,车辆动力响应显著增加,相比15m·s^(-1)时最大增加幅度为71.6%。

Taking the two design schemes（steel-box-truss and steel-truss schemes）of a three-line three-tower suspension bridge as the research object,the three-component coefficients of forces for vehicle and bridge were obtained by the wind tunnel tests of vehicle-bridge system section model.Based on the spatial dynamics model of wind-vehicle-bridge（WVB）system,the dynamic characteristics of bridge and the coupling vibration characteristics of WVB system were analyzed by using the self-developed software BANSYS. Analysis result indicates that the natural frequencies of three-line three-tower suspension bridge are comparatively low.The aerodynamic characteristics of vehicle were greatly affected by track position,and the drag coefficient of windward vehicle for the steel-truss scheme is about 2.2 times that for the steel-box-truss scheme.When wind speed is 0,the dynamic responses of bridge and vehicle increase with the increase of vehicle speed.The displacements of bridge for the steel-truss scheme are bigger than those for the steel-box-truss scheme at the same vehicle speed,which is resulted from the weaker whole stiffness for the steel-truss scheme.When wind speed is considered,the lateral responsesof bridge greatly increase with wind speed increasing.When vehicle is running on the windward side and wind speed increases from 15m·s^-1 to 25m·s^-1,the lateral displacements of bridge for the steel-box-truss and steel-truss schemes enlarge to approximate 2.4 times and 3.8times respectively,and crosswind is dominant to the lateral responses of bridge.On the whole,the bridge responses for the steel-truss scheme are larger than those for the steel-box-truss scheme under the same wind speed.As for the same scheme,vehicle responses increase with wind speed increasing.When wind speed reaches 25 m·s^-1 ,the dynamic responses remarkably increase,and the maximum response index increases by 71.6% compared with that at the wind speed of 15m·s^-1.