钢桥交通振动计算方法与动力特性研究

Research on computational method and dynamic characteristics of traffic vibration of steel bridge

针对正交异型钢面板的钢桥交通振动响应问题,提出一种新的计算方法.该方法对桥梁建立反映细部构造的板壳模型,以区别于以往的梁格模型;对车辆采用一种通用、简洁的有限元模型,可灵活地反映车辆体系;通过Newmark法求解桥梁与车辆的耦合振动方程.实例分析中对一座26m简支钢桥的交通振动进行了数值模拟,结果表明:1)按板壳模型计算得到的挠度冲击系数与梁格模型的结果接近,应力冲击系数则略大;2)板壳模型反映的桥梁高阶振型对高频的速度响应计算结果有一定影响;3)三维车辆模型得到的桥梁振动冲击系数小于二维车辆模型;4)简支钢桥交通振动中挠度动力响应的卓越频率较低,主要与低阶振型相关,速度响应的卓越频率则延伸至较高的频段.

A numerical method was presented for analysis of the traffic vibration of steel bridge with orthotropic steel deck.In this method,the bridge was represented by a shell model with detailed construction rather than the grillage model used before,a universal and simple finite element method was presented for a flexible vehicle,and the coupled dynamic equations of vehicle and bridge were solved by Newmark method.As an example,the traffic vibration of a simple-supported steel bridge with a span of 26 m was simulated.The results indicate that： 1） the impact factor of deflection from the shell model of bridge is similar with that from the grillage model,but the impact factor of stress is higher;2） the high-order vibration modes reflected by the shell model affect the calculated high-frequency velocity response in the traffic vibration of bridge;3） the impact factors in the traffic vibration of bridge from 3-D vehicle model are higher than that those from 2-D vehicle model;4） for the simple-supported steel bridge in the traffic vibration,the dynamic deflection is mainly related with the low-order vibration modes,but the velocity is related with the low and higher-order vibration modes.