大跨钢桁梁悬索桥风-车-桥分析系统建立与可视化实现

从钢桁梁断面风荷载和车辆荷载加载角度对现有风-车-桥耦合振动系统进行精细化改进。首先基于钢桁梁自身结构特性，以桁杆为单位，对静风力和抖振力，采用合力等效原则，使得任意时刻每个截面内所有节点所受静风力和抖振力的合力与作用在该截面形心的等效静风力和抖振力相等，求取每个节点的静风力和抖振力；对于自激力，依据刚体运动学理论，推导了钢桁梁截面节点与相应截面形心两者运动状态之间的关系式，采用响应不变原则，获取每个节点的自激力。其次在已建立适用于单主梁模型的分析系统的基础上，融入提出的钢桁梁风荷载精细化分析方法，构建大跨钢桁悬索桥风-车-桥分析系统，并基于OpenGL技术集成开发风荷载作用下随机车流过桥的动态可视化功能。最后依托一座典型大跨钢桁悬索桥，采用建立的分析系统，对不同风速和车流密度作用下的桥梁响应进行分析。结果表明：桥梁跨中竖向位移响应主要受车辆荷载控制，横向位移同时受风荷载和车流密度控制，但风荷载起主要作用；随着风速和车流密度的逐渐增大，跨中内力与位移响应极值明显增大。

Establishment and visualization of wind-vehicle-bridge analysis system for the large-span steel truss suspension bridge

The existing wind-vehicle-bridge coupling vibration system is improved and refined from the aspects of wind loading and vehicle loading on the section of steel truss girder. Firstly, the truss rod is taken as the analysis unit based on the structural characteristics of steel truss girder. The static and buffeting force are obtained by equivalence principle of resultant force, which implies that the resultant force of the static force and buffeting force of all the nodes within each section are equal to the equivalent static wind pressure and buffeting force at centroid of each section at any time. The relation of motion states between the nodes and the corresponding centroid of section is deduced based on the kinematics theory of rigid body, and the self-excited force at each node is acquired by the principle of invariant response. Secondly, the proposed improving or refining method is applied to the existing analysis system which is suitable for single beam model, and the wind-vehicle-bridge analysis system for large-span steel truss suspension bridge is established. Based on the OpenGL technology, the dynamic visualization functions of the random traffic flow across the bridge under wind load are developed. Finally, based on a large-span steel truss suspension bridge, the responses of the bridge under different wind speeds and traffic densities are analyzed with the established analysis system. The results show that the vertical displacement of the bridge shall bemainly controlled by the vehicle load, and the lateral displacement shall be controlled by the wind load and the traffic flow density, but the wind load shall play a major role. With the increase of wind speed and the traffic flow density, the maximum internal force and displacement response at the mid-span may increase remarkably.