1前言所谓固有振动是指弹性系统在没有外部动力的作用下形成的振动。固有振动反映系统的固有特性,是研究一切振动问题的基础[1]。因此准确求解桥梁结构的自振特性是桥梁振动问题的首要环节。在成桥后的荷载试验也往往通过脉动法测试桥梁的自振特性,通过与理论结果对比揭示桥梁的刚度情况。然而多次实践 1 Introduction The so-called natural vibration refers to the elastic system in the absence of external power formed by the vibration. Natural vibration reflects the inherent characteristics of the system and is the basis for studying all vibration problems [1]. Therefore, accurately solving the natural vibration characteristics of bridge structure is the most important part of the bridge vibration problem. After the bridge load test is often through the pulsation method to test the natural vibration characteristics of the bridge, compared with the theoretical results to reveal the stiffness of the bridge. However many times practice