风环境下大跨桥梁交通事故全程车流演化及其力学化、多尺度耦合关系建立和持续耦合效应评估关键问题

Assessment of traffic accident load effect of long-span bridges in wind environment covers the whole system of traffic load investigation-vehicle flow evolution and mechanization -analysis system-evaluation method: equipment system construction, key theoretical breakthroughs and simulation analysis flow are connected, and it is a cross-integration of multi-directions and multi-disciplines. Firstly, the traffic information collection and analysis system is constructed, the method of determining the impact area of the accident is proposed, and the evolution mechanism of the traffic flow in each space-time range of the impact area is explored. Based on the molecular dynamics theory of vehicle flu and the distribution of multi-workshop spacing, the model of car-following and lane-changing is established, and the simulation program is simulated. The simulation system of mixed evolution of multi-state vehicle flow is built to realize the whole process simulation of traffic accidents. Secondly, based on experiments, the mechanism of Tire-deck friction, coefficient model and adaptation mode are determined, and mechanized vehicle flow evolution is achieved. A multi-scale element interfacial force transfer method is formed; a micro-model wind and vehicle loading mode is formed by using resultant force and motion equivalence and reducing tire surface characteristics; and a multi-scale wind-vehicle-bridge analysis framework integrating vehicle flow evolution is constructed. Finally, starting from the continuous coupling of vehicle flow evolution and bridge response, a method of selecting load conditions is proposed, and the evaluation process is defined according to the scale characteristics. This project will promote the progress of basic theory of system coupling and engineering simulation technology, and improve the level of bridge health monitoring and evaluation, traffic organization and control and other related fields.

风环境下大跨桥梁交通事故荷载效应评估涵盖交通信息采集-车流演化及其力学化-分析系统-评估方法整个体系中设备系统建构、关键理论突破和仿真分析程序贯通，是多方向、多学科的交叉融合。首先建构交通信息采集分析系统，提出事故影响域动态确定方法，探究影响域各时空范围车流演化机理，以综合车流感知的分子动力学理论和多车间距分布建立车流跟驰和换道模型并程序仿真，衔接正常车流模块，构建多状态车流混合演化仿真系统，实现事故车流全程仿真。其次试验确定轮胎-桥面摩擦机理、系数模型及适配方式，力学化车流演化；形成多尺度单元界面力传递方法；采用力和运动等效、还原轮胎面化特性确立细观模型风和车辆加载模式；构建融合车流演化的多尺度风-车-桥分析框架。最后从车流演化与响应持续耦合出发，提出荷载工况段筛选方法，明确桥梁多尺度效应评估流程。本课题将促进系统耦合基础理论和工程仿真技术进步，提升桥梁安全评估、交通组织管控等领域水平。

风环境下大跨桥梁交通事故车流演化及其荷载化、分析系统建立和荷载效应评估是多方向、多学科的交叉。本研究以交通流演化的机理探究和数值仿真为重点，以风-车-桥分析系统为骨架，实现了系统在车流仿真、桥梁模型上的逐步精细，对桥梁关键附属构件进行了安全评估。首先以交通事故和天气事故两类典型事故的车流为研究对象，探究了车流演化机理和规律，初步实现桥上车流仿真。其次，通过实测轴距对标市场车型、纳入车辆前后悬和车流元胞的再细分，使得车辆在仿真交通流中得到精细的元胞表达；丰富车辆微观行驶决策因素、设定多级变速和变道优先权、纳入车流弯道行驶特性，从行驶规则上对直、弯桥上的车流行驶行为进行精细；构建了多状态车流混合演化精细仿真系统。第三，形成多尺度建模方法，实现桥梁主体和附属构件响应的一体分析。最后，形成对应于模型的车辆荷载加载方法，拉通了车流仿真和桥梁分析环节，对风环境中多种车流下直、弯桥的桥梁附属构件进行了有效评估。研究发现：大跨桥梁响应与车流分布密切相关，车流仿真的元素（元胞尺度、行进规则）对仿真结果有较大影响；桥梁主体和附属构件采用多尺度一体建模，可实现桥梁各部分评估数据的直接提取，结果较为直观和有说服力。本研究可为后续风-车-桥耦合振动理论研究和桥梁评估提供理论参考和分析平台，对提升桥梁健康监测系统仿真分析及相关学科的研究水平具有重要意义。