大跨度斜拉桥车桥耦合振动分析

Vehicle-Bridge Coupling Vibration Analysis of a Long-Span Cable-Stayed Bridge

摘要: 随着大跨度斜拉桥的广泛应用，车辆荷载作用下桥梁的动力响应问题日益受到重视。为研究车速和路面不平整度对大跨斜拉桥车桥耦合振动响应及冲击系数的影响规律，本文以某双塔双索面半漂浮体系斜拉桥为工程背景，采用ANSYS软件建立全桥三维有限元模型，基于车–桥系统力与位移协调条件，建立13自由度两轴四轮厢式货车模型，通过Newmark-β法进行时域迭代求解，开展了不同车速(30~90 km/h)和不同路面等级(A级~E级)工况下的车桥耦合振动分析。结果表明：桥梁跨中节点竖向位移和竖向加速度随车速增加呈“先增后减再增大”的复杂变化规律，车速90 km/h时冲击系数达最大值0.1672，较规范值高出234.4%，共振效应显著；随路面等级劣化(A级→E级)，跨中最大竖向位移由7.563 mm增至26.553 mm，增幅达3.51倍，冲击系数由0.0295增至2.6146，呈非线性增长趋势。研究揭示了大跨斜拉桥在车辆荷载作用下的动力响应特征及冲击系数的关键影响因素，可为同类桥梁的动力设计及运营维护提供参考。

Abstract: With the widespread application of long-span cable-stayed bridges, their dynamic response under vehicle loads has attracted increasing attention. To investigate the effects of vehicle speed and road surface roughness on the vehicle-bridge coupling vibration response and impact coefficient, a double-tower double-cable-plane semi-floating cable-stayed bridge is taken as the engineering background. A 3D finite element model is established using ANSYS, and a 13-DOF two-axle four-wheel van model is developed based on force-displacement coordination conditions. The Newmark-β method is used for time-domain solution under various speeds (30~90 km/h) and road grades (Class A to Class E). Results show that the vertical displacement and acceleration at mid-span exhibit a “first increasing, then decreasing, and then increasing again” trend with increasing speed. At 90 km/h, the impact coefficient reaches its maximum of 0.1672, which is 234.4% higher than the code value, indicating a significant resonance effect. As the road grade deteriorates (Class A to Class E), the maximum displacement increases from 7.563 mm to 26.553 mm (3.51 times), and the impact coefficient increases from 0.0295 to 2.6146 non-linearly. This study reveals the dynamic response characteristics and key influencing factors of the impact coefficient for long-span cable-stayed bridges under vehicle loads, providing a reference for the dynamic design and operation maintenance of similar bridges.