多车道并行随机车流作用下桥梁的响应机理与荷载模型研究

Vehicle load is a critical variable action that should be considered in bridge design and assessment. Currently, realistic stochastic traffic flow informed study on bridge load effects is the mainstream in domestic and overseas. However, most of the studies focus on the overall response of bridges, without revealing the differences and correlations of loading effects over lateral lanes under multi-lane parallel stochastic traffic flow, nor reflecting the contribution of the vehicle loads on certain lane to the overall response. Therefore, they are not able to address the situations that disease and damage are significantly diverse in bridge components of different lanes, which is also not covered by the existing multi-lane traffic load models in specifications. The objective of the project is to study the response mechanism and load model of bridges under multi-lane parallel stochastic traffic flow. First, the load correlation and stochastic features of multi-lane parallel vehicle sequences are investigated with measured traffic data. Based on which, relevant parallel coupling models are established and modelling methods of traffic flow are developed. Then, with loading responses of bridges under simulated multi-lane parallel traffic flow, multivariate extreme value prediction methods are employed to explore the response mechanism of multi-lane and overall load responses in arbitrary evaluation period. Finally, multi-lane traffic load models are proposed based on the parallel response mechanism, and their scientific expressions are explored to meet the requirements of various bridge spans. The research outcomes could provide theoretical supports for a wide range of engineering practices, such as the design of multi-lane bridges, operation and maintenance of in-service bridges, and improvement of traffic load models in specifications.

车辆荷载是桥梁设计与评估需考虑的重要可变作用，基于实际随机车流开展桥梁荷载响应分析是目前国内外的主流方法，但绝大多数研究关注的是桥梁总体响应，未深入揭示多车道并行随机车流作用下分车道荷载响应的差异及关联，也没有反映分车道荷载对总响应的贡献，因此难以科学回答运营中不同车道上桥梁构件所普遍存在的差异性病害及损伤，而这，现有规范多车道荷载模型也难以覆盖。本课题研究多车道并行随机车流作用下桥梁的响应机理与荷载模型。首先，通过实测交通数据研究多车道并行车队的荷载关联与随机特性，建立并行耦合模型并研发随机车流模拟方法；其次，针对多车道并行随机车流作用下的桥梁响应，采用多元极值推定方法揭示任意评估周期内的分车道及总体的荷载响应机理；最后，基于并行荷载响应机理提出多车道桥梁车辆荷载模型，并探索其科学表达形式，以适用于任意桥梁跨径。研究成果可为多车道桥梁设计、运营维护、规范荷载模型改进等提供理论支撑。

我国道路交通运输产业的蓬勃发展使得建设的桥梁结构越来越宽，为了提高交通流集散效率多车道往往实施按车型分车道行驶的交通规则，这使得各车道之间的荷载分布具有显著差异性，这种差异性随着车道数量增加、重车比例增多、交通流量增大而愈加显著，这种车道荷载差异特性在国内外现有研究和桥梁设计规范中均没有得到很好的体现。本项目深入揭示了多车道并行随机车流作用下桥梁分车道荷载响应的差异特性及关联规律，建立了基于车道荷载差异的桥梁多车道汽车荷载模型的统一模式、计算方法和分析工具。主要研究内容和成果如下：1.结合我国近十座典型多车道高速公路的实测车辆荷载数据，建立了反应多车道车流荷载并行耦合特性的数学模型，揭示了我国多车道高速公路车道荷载分布的不均匀规律；2.基于多车道车流荷载并行耦合特性和经典车桥耦合理论，开发了多车道随机车流与桥梁耦合动力数值分析方法和程序，并通过实桥跑车试验和桥梁静动力荷载效应对比验证了程序的计算精度和效率；3.提出了包含车道荷载修正系数和多车道荷载组合系数的多车道汽车荷载模型统一模式，能够反映我国多车道高速公路客观存在的车道荷载差异性规律；4.建立了基于车道荷载概率相遇理论的多车道系数计算方法，适用于中小跨径桥梁的多车道汽车荷载模型的参数取值计算；5.建立了基于车道荷载效应极端相遇的多元极值预测方法，适用于大跨径桥梁的多车道汽车荷载模型的参数取值计算；6.建立了考虑车道荷载差异的桥梁疲劳车辆荷载模型推定方法，推荐模型更能反应实际车流荷载作用下各个车道的桥梁构件疲劳损伤累积特性。研究成果在改扩建桥梁的多车道汽车荷载模型建立、旧桥结构可靠性评估、新桥维修加固车流管制等方面得到了应用实践。研究成果对我国公路桥梁汽车荷载模型及其横向折减系数的改进具有理论支撑意义，对改扩建桥梁多车道汽车荷载模型的建立具有直接参考价值，对既有多车道桥梁在运营随机车流荷载作用下的结构评估及荷载管理具有借鉴意义。