基于车桥耦合振动的连续梁桥动力特性研究

Study on Dynamic Characteristics of Continuous Beam Bridge Based on Vehicle-bridge Coupling Vibration

为获取连续梁桥在行车荷载作用下的动力特性规律,基于虚功原理,建立了24自由度典型四轴拖挂车动力学模型。采用模态叠加法建立三跨连续梁桥动力特性模型,通过模态综合法建立了车轮-桥面间的力学和位移耦合关系。组建了四轴拖挂车和连续梁桥动力耦合分析模型,通过逐步迭代法建立了车桥耦合时变矩阵方程。以某三跨连续梁桥为工程示例,进行车桥耦合动力特性的敏感性分析,重点分析了车辆行车速度、桥面不平度和车辆载重变化对桥梁关键位置处的动力响应影响。结果表明:随着行车速度的增大,桥梁竖向位移时程响应曲线整体呈增大趋势,其中边跨跨中竖向位移幅值增幅相对较小,为3.40%,中跨跨中竖向位移幅值呈先减小后增大的变化趋势,最大增幅为7.10%;随着桥面状况的恶化,桥梁边跨跨中和中跨跨中截面的竖向位移响应增幅相对较大,分别为38.60%和54.95%,为桥梁动力响应的主要敏感参数;当车辆载重相对较小时(从空载至40%满载),桥梁位移动力响应变化较为敏感,但随着车辆载重增长率的逐步增大,桥梁动力响应结果对车辆载重的敏感性逐步降低。

In order to obtain the dynamic characteristics of continuous beam bridge under driving load,a 24-DOF typical four-axle trailer dynamic model is established based on the principle of virtual work,and the dynamic characteristics model of three-span continuous beam bridge is established by using the modal superposition method.The mechanical and displacement coupling relationship between wheel and bridge deck is established by using the relevant theories of modal synthesis method.The dynamic coupling analysis model of four-axle trailer and continuous beam bridge is established,and the time-varying matrix equation of vehicle-bridge coupling is established by step iteration method.Taking a three-span continuous beam bridge as an example,the sensitivity analysis for vehicle-bridge coupling dynamic characteristics is carried out,and the influence of vehicle running speed,deck unsmoothness and vehicle load on the dynamic response at the key position of bridge is analyzed.The result shows that with the increase of traffic speed,the vertical displacement time-history response curve of the bridge increases as a whole.The vertical displacement amplitude of the side span increases relatively little(3.40%),while the vertical displacement amplitude of the middle span decreases first and then increases,with the maximum increase of 7.10%.With the deterioration of bridge deck condition,the vertical displacement response of the side span and mid-span section of bridge increases relatively greatly,which are 38.60%and 54.95%respectively,which are the main sensitive parameters of the bridge dynamic response.When the vehicle load is relatively small(from noload to 40%full load),the dynamic response of the bridge displacement is more sensitive,but with the increase of the growth rate of vehicle load,the sensitivity of bridge dynamic response to the vehicle load gradually decreases.The relevant study results can also provide reference for the dynamic response analysis and study for other types of bridges or structures.