本文通过对27m和30m预应力混凝土简支梁桥进行的动载试验,探讨了桥梁动力特性的分析方法,运用随机振动理论及数理系计原理,以随机量的数字特征(标准差)为参数定义了冲击系数.在试验的基础上,建立了车辆与桥梁相互作用的力学模型,应用数值分析的方法研究了车辆行驶速度、桥面平整度与车重对冲击系数的影响,计算结果与实测结果比较吻合. In this paper, dynamic test of 27m and 30m prestressed concrete simply supported beam bridges is carried out to discuss the analysis method of dynamic characteristics of bridges. Using the random vibration theory and principle of mathematical calculation, taking the random quantity of digital characteristics (standard deviation) as the parameter The impact coefficient is defined.Based on the experiment, the mechanical model of the interaction between vehicle and bridge is established, and the influence of vehicle speed, deck flatness and weight on the impact coefficient is studied by numerical analysis method. The calculated results are compared with the measured The results are more consistent.