沪苏通大桥风-车-桥耦合系统非线性动力响应研究

NONLINEAR DYNAMIC RESPONSE ANALYSIS OF WIND-TRAINBRIDGE COUPLING SYSTEM OF HU-SU-TONG BRIDGE

几何非线性是大跨度桥梁结构的主要非线性影响因素之一,对桥梁结构及桥上列车行车安全性的影响不容忽视。该文以世界首座跨度超1 km的公铁两用斜拉桥——沪苏通长江大桥为工程背景,基于桥址区复杂风场实测,采用谱表示法提取实际风场特征,模拟全桥三维风速场,建立了考虑复杂非线性空间特性的风荷载模型,考虑垂度效应、梁柱效应和大位移效应等几何非线性因素,建立了桥梁非线性计算子模型,采用全过程迭代法计算考虑非线性因素的风-车-桥耦合振动响应,并给出行车安全性分析。结果表明:考虑非线性因素工况下,桥梁与车辆的动力响应均有一定程度的增大,且车辆动力响应的低频成分显著增加;大位移效应对结构响应影响较大,梁柱效应影响较小;忽略非线性因素影响,可能导致响应分析偏小,评估偏不安全;当车速为200 km/h,瞬时风速超过35 m/s,或当瞬时风速为30 m/s,车速超过210 km/h时,车辆轮重减载率指标超出安全阈值,行车安全性受到威胁。沪苏通大桥的非线性风-车-桥耦合振动分析具有重要的科学研究意义,并对保障桥梁结构和列车运行安全具有重要的工程指导作用。

Geometric nonlinearity is one of the main nonlinear influence factors of long-span bridge structures.Its influence on the bridges and the running safety of trains cannot be ignored.The Hu-Su-Tong Yangtze River Bridge,the world's first super kilometer cable-stayed rail-cum-road bridge,is adopted as engineering background.Based on the in-situ wind field measurement,the actual wind field characteristics is extracted,and the spectral representation method is used to simulate the three-dimensional wind speed field of the bridge.The wind load model considering the complex nonlinear spatial characteristics is established.The bridge model is built up considering the geometric nonlinear factors such as the sag effect,beam column effect and large displacement effect.The whole-process iterative method is used to calculate the wind-train-bridge coupling vibration responses.The traffic safety analysis is given.The results show that considering the nonlinear factors increases the dynamic responses of the bridge and train to a certain extent and significantly increases the low-frequency component of the dynamic responses of the train.The large displacement effect has a greater impact on the structural response and the beam column effect has a less influence.Ignoring the influence of the nonlinear factors leads to inaccurate response analysis and unsafe evaluation.The wheel off-load index of the train exceeds the safety threshold when the train speed is 200 km/h and the wind velocity is more than 35 m/s,or when the wind velocity is 30 m/s and the train speed is more than 210 km/h.It means that the running safety of the train is threatened.The nonlinear windtrain-bridge coupling vibration analysis of the Hu-Su-Tong bridge has important scientific research significance and plays an important role in providing engineering guidance to ensure the safety of bridge structure and train operation.