考虑约束扭转的斜拉桥车激横向振动分析

利用有限单元法,基于力学原理和几何协调条件,导出了非对称箱型截面梁单元的弯扭耦合刚度矩阵,建立了斜拉桥在车辆荷载作用下的横向动力分析模型。由于考虑了箱梁的约束扭转,该模型能够分析复线或多线铁路桥在偏载作用下的横向振动问题。以桥梁轨道随机不平顺作为激振源,进行了机车过桥的实例分析。计算结果表明,桥梁的车激横向动力响应随车速及轨道不平顺样本的不同而变化,并随桥跨的增加而快速变得显著,车辆偏载对箱梁扭转振动有显著影响,所建立的力学模型是斜拉桥车桥耦合振动分析的实用模型。

The lateral dynamic analysis of cable-stayed bridge due to vehicle when considering restrained torsion

By using the finite element method of structural analysis,on the basis of mechanical theorem and geometric coordinative condition,the coupled flexure-torsion stiffness matrix of the beam element with asymmetric section are derived and a model of cable-stayed bridge for lateral dynamic analysis due to the vehicle is constructed.Considering the restrained torsion,we can analyze the lateral vibration of double-line or multiple-line railway bridges under unbalanced loads with the model.The random irregularities of the track on the bridge are taken as an exciting source to analyze the interaction between the vehicle and the bridge for two examples.The results obtained indicate that the lateral dynamic response varies with the change of vehicle speed and the samples of track irregularities,and becomes significant with the increment of the bridge span.Besides,the unbalanced load has significant influence on the torsion vibration.It is feasible to apply the mechanical model established in the paper to the dynamic analysis of the cable-stayed bridge under the vehicle.