车辆作用下的公路简支梁桥测试频率

Test frequencies freely supported beam of highway bridge under effect of vehicles

应用达朗伯(D'Alembert)原理和欧拉-柏努利梁(Euler-Bernoulli)假设,建立了多个车辆-桥梁系统相互作用的理论模型。利用模态分析方法,使车辆-桥梁系统方程解耦,基于广义坐标的自由振动理论,对用广义坐标矩阵形式表示的解耦后的运动方程用固有振动理论求解,从而得出多个车辆作用下的桥梁有载频率。对于中小跨径的公路桥梁,往往采用单个车辆激振桥梁,激振后停于桥上,因此推导出了单个车辆作用下的桥梁有载频率解析表达式。讨论了车辆的位置、弹簧刚度、簧上质量、簧下质量和桥梁有载频率与桥梁固有频率差值之间的关系。

A theoretical model was established for the interaetion of the multiple-vehicle and bridge system using the D＇Alembert principle and the hypothesis of Euler-Bernoulli beam.The motion equation of the vehicle-bridge system was decoupled by the model analysis method.The decoupled motion equation expressed in the matrix form of the generalized coordinates was solved by the eigenvibration theory to get the frequencies of the bridge loaded by vehicles.For the highway bridges with small or medium span,their vibrations were excited usually by a single vehicle,and the vehicle will stay on the bridge after excitation,so analytical expressions of the frequencies of the bridge under the action of a single vehicle were derived.The effects of the location of vehicle,the stiffness of its suspension spring,the mass above and under the spring on the difference between the loaded frequencies and the eigenfrequencies of the bridge were discussed.