钢桥疲劳损伤的冷维护方法及长期性能研究

In order to rationally extend service life and maintenance cycle for steel bridge, this project proposes cold maintenance concept for steel bridge fatigue damage. Full-scale model fatigue test, sophisticated numerical simulation, theory study and engineering application are adopted to study the long-term performance of typical steel bridge models, including orthotropic steel bridge deck reinforced with cold connected angle steel or steel plate, orthotropic steel bridge deck reinforced by cold composite ultra high performance fiber reinforced concrete (UHPFRC) overlay, out-of-plane distortion fatigue damage full-scale steel model strengthened by cold connecting angle steel. Long-term performances of full-scale models are studied under combination of vehicle load, environment corrosion, material and structure performance degeneration and so on. It is studied the fatigue and durability performance of steel bridge models strengthened by cold maintenance method. The steel bridge long-term performance monitoring, evaluation and prediction system is expected to be built. It is proposed the scientific cold maintenance methods and evaluation index. Research achievements of this proposal not only provide theoretical basis and key technical support for building steel bridge cold maintenance system, but also serve as significant references for establishing relevant specifications.

为了合理延长钢桥使用寿命与维护周期，本项目提出钢桥疲劳损伤的冷维护理念，采用足尺疲劳试验、精细化数值模拟、理论分析和工程应用相结合的研究方法，分别对采用冷连接角钢、钢板加固的正交异性钢桥面板，采用超高性能纤维混凝土（UHPFRC）冷连接组合层加固的正交异性钢桥面板、以及冷连接角钢加固后的面外变形疲劳损伤足尺模型，开展车辆荷载、环境腐蚀、材料与结构性能退化等多因素耦合作用下的长期性能研究，探究冷维护后钢桥的疲劳与耐久性能，建立冷维护后钢桥长期性能监测、评估与预测系统，提出科学的冷维护方法及评估指标。本项目研究成果不仅可为构建钢桥疲劳损伤冷维护技术体系提供理论依据和关键技术支撑，对编制有关规范亦可提供参考。

为了合理延长钢桥使用寿命和维护周期，解决工程实践的迫切需求，针对既有钢桥疲劳损伤维修加固方法存在的不足，提出了钢桥疲劳损伤的冷维护理念。本项目通过系列模型试验、数值模拟、理论分析和实桥应用，率先系统研究了钢桥面板、钢桥腹板间隙面外变形疲劳损伤冷维护的加固构造、工艺措施、有效性评价指标、长期耐久性能监测与评价方法。开展了正交异性钢桥面板疲劳损伤冷维护技术方案研究，主要包括合理冷连接方式、加固范围、加固几何构造等的优化研究，提出了钢桥面板典型疲劳细节的冷维护设计与加固工艺准则。研发了采用粘结新型剪力连接件的UHPFRC组合钢桥面板新体系，建立了UHPFRC组合钢桥面板的构造设计准则。研究了钢桥腹板间隙面外变形疲劳合理冷加固构造与工艺措施，建立了粘贴、栓接和混合连接钢板的加固设计准则，通过疲劳试验评估了冷维护方法的有效性和耐久性。建立了基于扩展有限元的钢桥面板、钢桥面外变形疲劳多尺度数值断裂力学模型，计入残余应力的影响，实现了多场作用、多型裂纹、跨尺度、全扩展过程的疲劳裂纹耦合精细化模拟，突破了疲劳裂纹加固后数值模拟评价的技术瓶颈。将本项目提出的钢桥疲劳损伤冷维护技术应用于某跨海大桥钢桥面板的疲劳裂纹加固，运用研发的疲劳损伤融合监测技术，实现了疲劳加固前后细节抗疲劳性能的监测，基于监测信息构建了冷加固后长期性能评估模型，工程应用和长期性能评价结果均表明钢桥疲劳损伤冷维护技术安全可靠、工程可实施性强。总结项目研究成果，编制了钢桥疲劳损伤冷维护方法及长期性能评价指南，为行业相关技术标准的编制提供了参考。