Based on the comprehensive application of continuous box girder bridge with variable cross section in bridge engineering currently, it' s difficult to get a analytical solution in vibration equation under moving vehicle loads. In this paper, bridge structural dynamics and the finite element method were adopted. Hermite interposition function of two-nodes for Euler-Bernoulli beam element was utilized. Based on presuming mode of a non-uniform rectangular cross section beams with parabolic variable heights in a plane, the stiffness matrix and mass matrix were deduced to analyze non-uniform members used in engineering structures increasingly. Precise time integral method was used in dynamic response and a numerical calculation program of dynamic response was worked out. The vibration response of continuous box girder bridge with variable cross section in a project of changsha city under moving vehicle loads was analyzed. Influence of vehicle speed and acceleration changes to bridge deflection was studied. Simulation results were compared with some previously published literatures, and bridge deflection can satisfy specification. It was shown this bridge has a better rigidity.%基于桥梁工程中广泛应用的变截面连续箱梁桥受移动车辆荷载作用时的振动方程解析解难以得到,本文运用桥梁结构动力学和有限元方法,对Euler-Bernoulli梁单元采用二节点的Hermite形函数,在假定的变截面模式基础上,推导了梁高呈抛物线变化箱形截面梁单元的刚度矩阵和质量矩阵.在时域中采用精细时程积分法,编制了桥梁动力响应数值计算程序,对长沙市某工程中变截面连续箱梁桥在车辆通过时的振动响应进行了分析,研究了车辆速度和加速度变化对桥梁挠度的影响.模拟结果与已发表的文献吻合较好,挠度满足规范要求,表明该桥具有良好的刚度.
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