考虑伸缩缝参数影响的连续梁桥车-桥耦合动力响应研究

Analysis of vehicle-bridge coupling vibration considering the influence of expansion joint

伸缩缝劣化对车-桥耦合动力响应规律影响显著。为考虑伸缩缝参数变化对车-桥耦合动力响应的影响,结合车-桥耦合动力响应分析方法及车轮过缝的力学特性,提出了车轮过缝单点接触时变力模型。并采用伸缩缝局部振动模态提取法及模态综合法建立了考虑伸缩缝参数影响的车-桥耦合动力响应分析模型(车-缝-桥耦合动力响应分析模型)及其数值求解方法,并基于实测数据验证。进而以实测三跨连续梁桥为对象,探究了车辆过缝与否,伸缩缝高差、间隙,车速、车辆布置、车质量等参数对车-缝-桥耦合动力响应的参数影响规律。结果表明:端部支座外侧设置伸缩缝,会降低连续梁桥主梁跨中位移响应,但会增加桥梁端部的车致冲击作用;相同桥长条件下,车辆过缝会增大桥梁的位移和加速度响应,且加速度响应增大更为明显;伸缩缝高差会降低第一跨的竖向位移响应,但会增大其他两跨的竖向位移响应,伸缩缝高差对不同区域的车致冲击作用(系数)影响显著;伸缩缝附近车致冲击作用随伸缩缝间隙的增大而增大;车速较低时,主梁竖向峰值位移和冲击系数波动较小,并在80 km/h车速附近出现峰值;主梁各跨跨中的动位移均随着车辆数目的增多而增大,但各跨跨中的位移冲击系数不一定增加;桥梁冲击系数随车质量的增加而减小。在桥梁设计时应考虑伸缩缝参数变化对桥梁不同区域车致冲击作用变化的影响。

The deterioration of expansion joints has a significant effect on the vehicle-bridge coupling vibration response.To establish an analysis method for the vehicle-bridge coupling vibration considering the influence of expansion joint,a single point contact time-varying force model was proposed based on the analysis of the vehicle-bridge coupling dynamic responses and the mechanical characteristics of a wheel over joint.Then,an analysis model for the vehicle-joint-bridge coupling vibration was established based on the local vibration mode extraction and mode synthesis method and its numerical solution method.Its effectivity was verified by the field-testing data.Then,taking a three span continuous beam bridge as an example,the influences of the factors such as the vehicle passing through the joint,the height difference of the expansion joint,the gap,the vehicle speed,the vehicle layout and the vehicle weight on the dynamic responses of the vehicle-joint-bridge coupling vibration was studied.The result indicates that the expansion joint at the outside of the end support will reduce the displacement response of the main beam in the middle of the span,but will increase the vehicle impact effect at the ends of the bridge.Under the same bridge length,the vehicle passing through the joint will increase the displacement and acceleration responses of the bridge,and the acceleration response will increase more obviously.The height difference of the expansion joint will reduce the vertical displacement response of the first span,but the vertical displacement responses of the other two spans will increase.The height difference of the expansion joint has a significant effect on the vehicle impact in different regions.The vehicle impact effect near the expansion joint increases with the increase of the expansion joint gap.When the vehicle speed is low,the fluctuation of the vertical peak displacement and impact coefficient of the main beam is slight,and the peak value appears near the vehicle speed of 80 km/h.The dynamic displacement of each span of the main beam increases with the increase of the number of vehicles,but the displacement impact coefficient of each span does not necessarily increase.The bridge impact coefficient decreases with the increase of vehicle weight.In the design of bridges,the influence of the change of expansion joint parameters on the impact induced by vehicles in different regions of the bridge should be considered.