考虑节点刚域影响的钢-混组合桁架梁桥行车动力响应分析

为研究节点刚域对钢-混组合桁架梁桥行车动力响应的影响规律,以某新建桥梁为例,利用自主开发的TRBF-DYNA软件开展列车-轨道-桥梁耦合系统振动响应研究.分别采用有限元方法建立考虑节点刚域的轨道-桥梁子系统整体三维模型;采用多刚体动力学方法建立31自由度车辆子系统模型,应用轮轨空间滚动接触模型模拟轮轨间可分离的接触关系.首先分析了节点刚域对桥梁自振特性的影响;继而研究了节点刚域和行驶线路对列车走行性以及桥梁整体和局部杆件动力响应的影响.结果表明:考虑节点刚域显著提高桥梁刚度;同时,桥梁的竖向振动位移峰值和加速度峰值减小30.00%~35.15%;钢腹杆内力显著提升,其中弯矩会增大90.41%~224.02%;但节点刚域对列车行车安全性指标影响较小.双线行车较单线行车引起的桥梁动力响应显著增强,其中横竖向加速度峰值将分别增大114.29%和100%;钢腹杆的应力有所增加,但并非成倍增加.建议在研究钢-混组合桁架梁桥行车动力响应时考虑节点刚域的影响.

Driving Dynamic Response Analysis of a Steel-concrete Composite Trussed Girder Bridge Considering the Effect of Nodal Rigid Zone

In order to study the influence of nodal rigid zone on the dynamic responses of a steel-concrete composite trussed girder bridge under high-speed train, one railway bridge is taken as a numerical example and the self-developed software TRBF-DYNA is utilized to calculate the dynamic responses of train-track-bridge coupled system. The whole three-dimensional model of the track-bridge subsystem is established by using finite element method, where each vehicle of the train is modeled as 31 degrees of freedom model by applying the rigid-body dynamics theory, and the spatial rolling contact model is used to simulate the interaction between wheel and rail. Firstly, the influence of nodal rigid zone on the bridge vibration characteristics is studied. Then, the effects of the nodal rigid zone and running lane on the vehicle running safety indexes and dynamic responses of local steel truss webs and global bridge are investigated. The analysis results show that the nodal rigid zone improves the stiffness of the bridge. Meanwhile, the maximum vertical displacement and vertical acceleration of the bridge are reduced by 30.00%~35.15%. Moreover, the internal force of steel truss webs increases significantly, particularly the bending moment increases up to 90.41%~224.02%, and the nodal rigid zone has little influence on the safety indexes of vehicle. Compared with single-lane driving, the dynamic responses of the bridge with double-lane driving are markedly increased, and the peak value of the lateral and vertical accelerations are increased by 114.29% and 100%, respectively. Stress of the steel truss webs increases, but it is not linearly increased according to the number of running lane. It is suggested that the influence of the nodal rigid zone should be considered in the evaluation of the dynamic responses of steel-concrete composite trussed girder bridges.