鹅公岩大桥动力特性分析

Research on Dynamic Characteristics of Egongyan Bridge

以重庆市鹅公岩大桥为工程案例,对大跨径自锚式悬索桥的动力特性进行研究。基于MIDAS/CIVIL软件建立全桥有限元模型,采用非线性有限元与子空间迭代相结合的方法,具体分析矢跨比、边中跨比、构件刚度以及服役期荷载集度、温差等参数对600m跨径的自锚式悬索桥动力特性的影响规律。研究结果表明:成桥状态下,结构基频为0.103 1 Hz,加劲梁纵飘振型起主导作用;矢跨比的改变使多阶模态的频率受到影响,其中,加劲梁振动受到的影响最为显著;边中跨比主要影响结构的竖向振动,减小边中跨比有利于提高结构的整体刚度;主缆抗拉刚度对频率的影响较小,反之,主梁抗弯刚度对结构的竖向及横向频率的影响较为显著;桥梁服役期间,模态频率受恒载集度、温差因素的影响不可忽略。

In this paper, the dynamic characteristics research of large span self-anchored suspension bridge was based on the engineering background of Egongyan Bridge in Chongqing. The calculation model of self-anchored suspension bridge was established in MIDAS/ CIVIL software. In order to analyze the dynamic characteristics of self-anchored suspension bridge with 600 meters span under the influence of the ratio of rise to span,side to span,component stiffness,dead load intensity and temperature on the dynamic characteristic were analyzed by using the method combining subspace iteration and nonlinear finite element. In view of the fact that a lot of researchs are mainly for medium-span self-anchored suspension bridge which less than 500 meters span,so the dynamic characteristics research of large span self-anchored suspension bridge has practical significance. The result shows that first order frequency is 0. 103 1 Hz in the finished state and longitudinal floating mode plays a leading role. The changes of ratio of rise to span affects frequencies on the vibration modes and frequencies of the different orders,which vibration of main girder has a great influence. The influence of the side to span on the vertical bending vibration,and the reduction of the mid span ratio is beneficial to improving the overall stiffness of the structure. The stiffness of the cable has little effect on the frequency, while the bending stiffness of the bending has great influence on the vertical and horizontal frequencies of the structure. The modal and frequency cannot be ignored by the load patterns and temperature changes during the bridge operation.