三线合一、三塔悬索桥风8车8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25 m？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15 m？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25 m？s-1时,车辆动力响应显著增加,相比15 m？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 responses of bridge greatly increase with wind speed increasing. When vehicle is running on the windward side and wind speed increases from 15 m？s-1 to 25 m？s-1, the lateral displacements of bridge for the steel-box-truss and steel-truss schemes enlarge to approximate 2.4 times and 3.8 times 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 15 m？s-1. 4 tabs, 18 figs, 22 refs