大跨度公路斜拉桥车桥耦合振动竖向响应分析

摘要

在数值分析软件MATLAB平台上,运用三角级数法将桥面不平顺模拟为具有各态历经的平稳随机过程.根据有限元法建立大跨度斜拉桥分析模型,将车辆模拟为5个自由度的质量-弹簧-阻尼体系,分别建立车辆和桥梁结构的振动微分方程,通过位移协调和力的平衡条件形成车桥系统的耦合振动微分方程.采用Newmark-β法,利用有限元分析软件ANSYS编写了迭代计算的APDL命令流,进行主跨为550 m的福建长门大跨度公路斜拉桥的车桥耦合振动分析.计算结果表明:桥梁结构动力响应随桥面状况的恶化而显著增大,随结构阻尼的增大而近似呈线性关系减小.随车重的增加而先增大后减小,在开始阶段,响应迅速增大,而后缓慢减小.%On the platform of numerical analysis software named MATLAB,road surface roughness was simulated as stationary random process with ergodicity by trigonometric series method.The finite element analysis model of highway cable-stayed bridge with long span was established with finite element method,and a vehiele was imitated as a mass-spring-damp system with five DOFs.Vibration differential equations of vehicle and bridge were established respectively and coupled by compatibility of displacement and equilibrium of force.Newmark-β method and APDL command stream compiled for iterative computations were used to analyze the dynamic response of Changrnen bridge with long span of 550 m.The calculation results indicated that dynamic responses of bridge structure increased when road surface roughness became worse,chiefly linearly decreased when structural damping ratio increased,and first quickly increased and then slowly decreased when vehicle weight increased.