考虑体系冗余性及其经时变异性的RC简支T梁桥可靠度评估方法

The security assessment and performance prediction of existing bridge are very effective to prevent serious traffic accident.Traditional methods mostly focus on component level, the design calculation model is employed to evaluate the structure system,and Without considering the effect of material degradation on system force transmission pattern. It may be cause conservative or dangerous assessment conclusion.According to the bearing redundancy and its time- variability characteristics of multi- beam system, the flexural bearing redundancy identification technology is developed using probability, stochastic process theory and fiber element- based nonlinear analysis technology, combining the experiment and numerical simulation method. By five sets of numerical experiments, the redundancy influence law of T beam system is revealed, the system model correction method considering the failure correlation of the main girders is proposed, and the redundancy parameter library of T beam system is established. The time-dependent evolution rule causing by material degradation of system force transmission pattern is revealed. The system performance prediction model considering time-variability and randomicity of redundancy is established using the probability analysis method. System-level structural safety evaluation and prediction is achieved ultimately .The research results would provide new ideas and new methods for security assessment and performance prediction method of typical multi-beam RC simply supported T beam bridges, and a reliable measure for system redundancy release and utilization during assessment and reinforcement.

对既有梁桥进行安全性评估与性能预测可有效预防重大交通事故的发生。传统方法大多专注于构件层次，仍采用设计时的计算模式来评估结构；且未考虑材料退化对体系传力格局的改变，其对结构的安全性可能会产生或保守或危险的结论。针对多梁式体系的承载冗余性及其经时变化特性，本课题将结合试验和数值仿真手段，综合运用概率、随机过程理论和基于纤维单元的非线性发展全过程分析技术，开发弯曲承载冗余性的辨识技术；通过五组数值模拟试验，揭示T梁体系冗余性的影响规律，提出考虑主梁失效关联的体系模型修正方法，进而建立T梁体系冗余性参数库。揭示材料退化引起的体系传力格局的时变演化规律，采用概率解析法建立考虑冗余度随机时变的体系性能预测模型，最终实现体系层次的结构安全评价与预测。课题研究成果将为公路典型多梁式RC简支T梁桥的状态评估与性能预测等关键问题提供新思路和新方法，为评定与加固中体系冗余度的释放与利用提供可靠的度量尺度。

课题针对公路典型多梁式RC 简支T 梁桥体系，探索能够考虑承载冗余性的状态评估，以及反映冗余性变化过程的性能预测方法。首先，阐明T 梁体系弯曲承载破坏过程的传力机理与影响，明确传统计算模式与体系承载极限分析的关系，提出体系冗余性的度量指标；开发体系弯曲承载冗余性的辨识技术，建立考虑冗余性的体系概率评估模型；为最新版交通部部版通用图，建立公路典型多梁式RC 简支T 梁桥的冗余性数据库，用于工程查询。其次，阐明拓扑形式、延性及相关性三因素对T 梁体系冗余性的作用机制与影响规律，并建立考虑上述三因素影响的修正模型。然后，阐明材料退化对T 梁体系传力机理改变的作用机制，明确退化过程中体系可能的传力格局与对应的失效模式；进而建立考虑体系传力格局随机时变的体系评估模型。最后，揭示弯、剪失效机制对T 梁体系失效行为的影响；建立多重失效机制下的考虑体系传力格局随机时变的体系评估模型。通过本研究，建立了部版标准T梁桥图的冗余度数据库，开发了性能评价软件，能够1) 明确体系承载冗余性的作用机制，揭示其影响因素的作用规律，开发弯曲承载冗余性的辨识技术，建立可考虑冗余性的评估模型与配套的系数表，为评定与加固中体系冗余储备的释放与利用提供可度量的尺度。2) 阐明退化过程中既有结构其传力机理及体系计算模式可能发生改变的原因，揭示材料退化对体系冗余性变化的随机影响规律，建立考虑体系传力格局随机时变的体系评估模型，为体系的状态评估和性能预测提供技术支撑。