湿热环境与过载谱下CFRP加固RC桥梁构件疲劳性能研究

Fatigue/durability mechanism of reinforced concrete (RC) bridge members strengthened with carbon fiber reinforced polymer (CFRP) is discussed considering the time-varying hot-wet environment and vehicle overload coupling effect in this research, because of the typical service environment of highway bridges in subtropical areas is hot-wet environment, and vehicle overload is the living load which would cause the most serious damage of bridge structure. On the one hand, the definition method of vehicle overload is proposed by structural calculations and theoretical analyses, and some vehicle overloading spectrums in typical road are generated with a lot of vehicle load information collection, statistical analyses and numerical simulations. Using a testing system developed by our research group, a fatigue/durability experimental method is proposed for RC bridge members strengthened with CFRP under hot-wet environment and vehicle overload coupling action. On the other hand, the effect mechanism of overload spectrum type, amplitude and sequence on the fatigue/durability performance of the strengthened beams is proven preliminary with the experimental studies and theoretical analyses. The coupling effect of hot-wet environment and overload on the fatigue/durability performance of the strengthened RC members is developed. And then, an evaluation method of fatigue/durability of the RC members strengthened with CFRP is proposed considering hot-wet and overload coupling effect for the anti-fatigue/durability design of the servicing bridges, to provide a scientific basis for maintenance and management of the highway bridges.

针对亚热带地区公路桥梁的典型服役环境——湿热环境与对桥梁结构危害甚大的活载——车辆过载的耦合作用效应，以碳纤维增强复合材料（CFRP）加固钢筋混凝土（RC）构件为研究对象，探讨时变的湿热环境与车辆过载的耦合/共同作用下CFRP加固RC桥梁结构件的疲劳/耐久性机理。一方面，通过结构计算和理论分析，提出车辆过载的界定方法；通过大量车辆载荷信息的采集、统计分析和数值模拟，生成典型公路的车辆过载谱；利用研发的实验平台，提出湿热环境与车辆过载谱的耦合/共同作用下CFRP加固RC桥梁构件的疲劳/耐久性实验方法。另一方面，通过实验研究和理论分析，初步探明过载谱的谱型、幅值、顺序对加固构件抗疲劳/耐久性能的影响机制、以及湿热环境与过载对加固构件疲劳/耐久性能的耦合作用效应，提出湿热环境与过载耦合/共同作用下FRP加固RC桥梁构件的抗疲劳/耐久性能的评价方法，为在役桥梁的加固设计、养护和管理提供科学依据。

针对亚热带地区公路桥梁的典型服役环境“湿热环境”与对桥梁结构危害甚大的活载“车辆过载”的耦合作用效应，本项目以碳纤维增强复合材料（CFRP）加固钢筋混凝土（RC）构件为研究对象，开展了以下研究：1）提出车辆过载的界定方法、以及湿热环境与车辆过载谱的耦合/共同作用下CFRP加固RC桥梁构件的疲劳/耐久性实验方法；2）探讨过载谱对加固构件抗疲劳性能的影响机制、以及湿热环境与过载对加固构件疲劳/耐久性能的耦合作用效应，提出湿热环境与过载耦合下FRP加固RC桥梁构件抗疲劳/耐久性能的评价方法。取得了以下主要研究成果：.1）提出了公路桥梁的车辆过载的概念、过载的界定及应用方法，模拟和编制了典型公路/城市道路的车辆三阶梯过载谱；.2）提出了湿热环境与车辆变幅过载谱耦合/共同作用下公路桥梁承载构件的疲劳实验方法，成功地实施了湿热环境与车辆变幅过载谱耦合/共同作用下公路桥梁承载构件的环境疲劳/耐久性实验；.3）提出了湿热环境与车辆变幅过载耦合/共同作用下FRP加固RC构件中主裂纹疲劳扩展实验方法，初步实现了该类裂纹的扩展实验；.4）初步探明了过载阶梯谱对碳纤维薄板（CFL）增强RC梁疲劳寿命的影响规律，并与常幅、随机载荷作用下CFL增强RC梁的疲劳寿命进行了对比分析。研究结果表明，在相同（平均）荷载水平下，过载阶梯谱下加固梁的疲劳性能比常幅循环载荷下的降低得较多（疲劳极限降低13%）；.5）初步探明了变幅过载与湿热环境耦合/共同作用下CFL加固RC梁的疲劳破坏机理，提出了变幅过载与湿热环境耦合/共同作用下加固梁疲劳性能/耐久性的分析方法，建立了修正Miner准则、以及基于该准则的加载水平等效方法，在此基础上建立了CFL加固RC梁在变幅过载下的湿热环境疲劳方程，并陆续在公路旧危桥的FRP加固RC结构的耐久性评估中得到了成功的应用，取得了重大的社会和经济效益。.本项目共申请了发明专利13项（外国3项）、授权3项（外国2项）；发表了期刊论文29篇；获得教育部科技成果一等奖1项。