基于车流—桥耦合的斜拉桥动力响应及相关问题研究

发布时间：2018-04-05 00:29

本文选题：CA模型　切入点：公路桥　出处：《广州大学》2017年硕士论文

【摘要】：随着现代汽车运输和桥梁结构的发展,汽车运输呈现“重载化、高速化”及桥梁呈现“大、轻、柔”化,使得车辆与桥梁的耦合动力效应愈加明显,导致车-桥耦合系统诱发的动力荷载将可能远远大于静力荷载,车-桥系统的时变频率问题也会显现,从而引起桥梁结构的损伤、疲劳、开裂,降低桥梁结构寿命、安全可靠度和车辆运行舒适度。为此,本文基于国家自然科学基金项目—“一种基于元胞自动机车流的公路桥三维耦合振动分析方法研究”(项目批准号:51208125),开展基于车流-桥耦合的斜拉桥动力响应及相关问题研究,主要开展的工作如下:(1)基于元胞自动机的随机车流模拟引入微观交通流模型(元胞自动机模型)模拟公路桥梁上随机车流,模型充分考虑车道内车辆运行规则和车辆换道规则,以及车流中车辆的加速、减速、变道、超车等。研究了不同限速及车流密度下的随机车流,并与已有文献中的车辆航测图进行对比,验证了所建立模型的正确性。(2)基于随机车流的车流-桥耦合振动研究基于ANSYS整体环境,建立车流-三维桥耦合振动分析模型,模型中的桥梁模型与车辆模型独立建模,给出车流-公路桥耦合振动分析方法。研究不同车流密度及车辆最大限速条件下车流-桥系统的耦合动力响应。分析结果表明:车流密度及限速条件对耦合响应结果有较大影响,高车流密度明显大于低车流密度下的跨中控制截面的动挠度峰值;车辆最大限速也是影响跨中挠度的因素,跨中控制截面动挠度峰值随着桥上车辆最大限速的提升亦不断变大。(3)车流-桥系统的时变频率研究将车-桥系统简化为梁-质量系统,推导得到三种边界条件下梁-移动质量系统和梁-固定质量系统的频率方程,对比研究梁-移动质量系统和梁-固定质量系统的频率,结果表明:一般情况下的车-桥系统,桥-移动车辆系统的频率可由桥-固定车辆系统的频率替代。以此结论为基础,开展车流作用下车流-桥系统的时变频率研究,对模型前三阶竖弯频率进行分析发现:桥梁自振频率大于基于CA模型的车桥系统的各阶时变频率。车流-桥系统的前三阶竖弯频率随车流密度的增加而减小。(4)基于车流-桥耦合的拉索疲劳寿命评估及可靠度分析基于车流-桥耦合分析计算获得结构构件的应力时程,利用雨流计数法对构件的应力时程进行统计,进而获得应力直方图,求得构件等效应力幅,基于S-N曲线、Miner理论对桥梁进行疲劳寿命及疲劳可靠度分析,初步探讨了车流密度对拉索疲劳寿命及疲劳可靠度的影响。
[Abstract]:With the development of modern automobile transportation and bridge structure, automobile transportation presents "heavy load, high speed" and bridge "big, light and soft", which makes the coupling dynamic effect between vehicle and bridge more obvious.The dynamic load induced by the vehicle-bridge coupling system will probably be much larger than the static load, and the time-varying frequency problem of the vehicle-bridge system will also appear, which will cause damage, fatigue, cracking and reduce the life of the bridge structure.Safety reliability and vehicle running comfort.To that end,Based on the National Natural Science Foundation of China-"A study on Three-dimensional coupled Vibration Analysis of Highway Bridges based on Cellular Automata vehicle flow" (Project Grant No.: 51208125), the dynamic response of cable-stayed bridges based on vehicle-bridge coupling and related problems are studied.The main work is as follows: (1) based on cellular automata, stochastic traffic flow simulation is introduced into microscopic traffic flow model (cellular automata model) to simulate the random traffic flow on highway bridges. The model fully considers the vehicle running rules and the vehicle changing rules in the driveway.And the vehicle in the traffic acceleration, deceleration, change of track, overtaking, etc.The random vehicle flow under different speed limit and vehicle flow density is studied, and compared with the existing vehicle aerial survey diagram, the correctness of the established model is verified. 2) the research of vehicle-bridge coupling vibration based on stochastic vehicle flow is based on ANSYS environment.An analysis model of vehicle-three-dimensional bridge coupling vibration is established, in which the bridge model and vehicle model are independently modeled, and the method of vehicle-road bridge coupling vibration analysis is presented.The coupled dynamic response of vehicle-bridge system with different vehicle flow density and maximum vehicle speed limit is studied.The results show that the vehicle flow density and the speed limit condition have great influence on the coupling response results, the high vehicle flow density is obviously larger than the dynamic deflection peak of the control cross section under the low vehicle flow density, and the maximum vehicle speed limit is also the factor affecting the mid-span deflection.The time-varying frequency of vehicle-bridge system is simplified to beam-mass system with the increase of the maximum speed limit of the vehicle on the bridge.The frequency equations of beam-moving mass system and beam-fixed mass system are derived under three boundary conditions. The frequency of beam-moving mass system and beam-fixed mass system are compared.The frequency of the bridge-mobile vehicle system can be replaced by the frequency of the bridge-fixed vehicle system.Based on this conclusion, the time-varying frequency of vehicle-bridge system under the action of vehicle flow is studied. The first three vertical bending frequencies of the model are analyzed. It is found that the natural vibration frequency of the bridge is higher than the time-varying frequency of the vehicle-bridge system based on CA model.The first three order vertical bending frequency of vehicle-bridge system decreases with the increase of vehicle flow density. (4) based on vehicle-bridge coupling, the fatigue life evaluation and reliability analysis of cables are carried out. Based on vehicle-bridge coupling analysis, the stress time history of structural members is obtained.The stress time history of the component is counted by rain flow counting method, and the stress histogram is obtained, and the equivalent stress amplitude is obtained. The fatigue life and fatigue reliability of the bridge are analyzed based on the S-N curve Miner theory.The influence of vehicle flow density on fatigue life and fatigue reliability of cable is discussed.
【学位授予单位】：广州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U448.27;U441

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