车桥耦合作用下简支钢梁桥时变动力特性试验研究

Experimental study on time-varying dynamic characteristic of simply supported steel girder bridge under vehicle-bridge coupled

为研究车-桥耦合作用下简支钢梁桥动力特性的时变规律,设计弹簧小车-简支钢梁桥模型试验,通过一系列静载与动载测试工况,利用监测的振动响应数据,得到不同车体质量、运行速度下简支钢梁桥的跨中动挠度、动力放大系数等参数的变化情况;并对简支钢梁桥在环境激励、跑车激励下的模态参数进行识别,分析其时变规律。试验结果表明:无论是跑车激励工况还是基于短时时不变工况,简支钢梁桥的跨中动挠度、动力放大系数分别随着车重、速度增加而增大;简支钢梁桥的一阶频率成半正弦时程性变化,频率最大下降53%;车辆作用下简支钢梁桥阻尼比无明显规律性变化,但变化值都比环境激励下简支钢梁桥的值要大。

In order to study the time-varying rule of the dynamic characteristics of the simple supported steel girder bridge under the vehicle-bridge coupled vibration,the model test of the spring trolley simple supported steel girder bridge was designed.Through a series of static and dynamic load tests,the dynamic deflection of mid-span and dynamic magnification factor of simply supported steel beam bridge was obtained under different vehicle body mass and running speed,according to the monitored vibration response data.The modal parameters of the simple supported steel beam bridge under the environmental and roadster incentive were identified.The time-varying rule was analyzed.The following results are obtained.The dynamic deflection of mid-span and dynamic magnification factor of the simple supported steel girder bridge increase with the increase of vehicle weight and speed.The frequency of the simple supported steel girder bridge changes in half sine time history.The first-order frequency decreases by 53%at most.And the damping ratio of simply supported steel beam bridge under the action of vehicle has no obvious regularity.The change value is higher than that of the environmental excitation.However,the variation value is larger than that of simply supported steel girder bridge under environmental excitation.