CFRP加固锈蚀钢结构疲劳性能提升机制及耐久性研究

Many steel structures exposed to harsh environment such as industrial and offshore atmosphere for a long time will inevitably be corroded severely, even if protective and structural measures are both employed. The resultant corrosion pits will not only reduce the ductility and fracture toughness of steels, but also promote the initiation and propagation of a crack. Moreover, corrosion pits acting as geometrical discontinuities, can lead to stress concentration and apparently raise the local stress level, and thus have a great harmful influence on fatigue performance of steel structures. This project takes the steel structures subjected to drying-wetting cycles, acidic atmosphere and neutral salt spray environments as the research objects. By conducting a series of experimental investigations, combined with theoretical analysis and numerical simulations, the mechanism of CFRP enhancing the fatigue performance of corroded steel structures is studied to reveal the effects of CFRP stiffness and pre-stressing degree on stress concentration, crack initiation and propagation and fatigue life, and subsequently a fatigue life prediction model considering these two factors established for CFRP reinforced corroded steel structures. To mitigate the effects of corrosion on fatigue performance, the reliable and quantificational fatigue design theory and method applicable for CFRP reinforced corroded steel structures are also put forward. In addition, researches on durability of CFRP reinforced corroded steel structures are carried out to reveal the degradation mechanism of fatigue performance of CFRP reinforced corroded steel structures when subjected to corrosion environments, and finally propose a fatigue life prediction method corresponding to different corrosion environment. All these researches will offer great help for further improvement of evaluating theory of existing steel structures, and also provide technical support to disaster prevention in civil engineering.

许多长期处于工业、海洋大气等腐蚀环境下的钢结构工程，往往难以通过防护和构造措施避免锈蚀。钢结构表面锈坑降低了钢材塑性和断裂韧性，加快其裂纹萌生与扩展，造成钢材局部应力集中，对其疲劳性能产生非常大的影响。本项目以干湿交替、酸性大气和中性盐雾环境下锈蚀钢结构为对象，采用试验研究、理论分析与数值模拟相结合的方法，研究碳纤维增强复合材料（CFRP）加固锈蚀钢结构疲劳性能提升机制，揭示CFRP预应力度、刚度对锈蚀钢结构应力集中、裂纹萌生与扩展、疲劳寿命的影响，建立与CFRP预应力度、刚度等因素相关的锈蚀钢结构疲劳寿命计算模型，提出CFRP加固锈蚀钢结构疲劳性能设计理论与方法；开展CFRP加固锈蚀钢结构疲劳性能在腐蚀环境下的耐久性研究，明确其疲劳性能在腐蚀环境下的劣化机理，提出其在腐蚀环境下的疲劳寿命退化模型，进一步完善我国既有钢结构加固设计与评估理论，为我国土木工程灾害防御提供技术支持。

本项目腐蚀环境下既有钢结构疲劳性能加固为工程背景，以“CFRP加固锈蚀钢构件疲劳性能的提升和耐久”为研究问题切入点。采用试验研究、理论分析与数值模拟相结合的方法，研究了碳纤维增强复合材料（CFRP）加固锈蚀钢结构疲劳性能提升机制，揭示了CFRP预应力度、刚度对锈蚀钢结构应力集中、裂纹萌生与扩展、疲劳寿命的影响，建立了与CFRP预应力度、刚度等因素相关的锈蚀钢结构疲劳寿命计算模型，提出了CFRP加固锈蚀钢结构疲劳性能设计理论与方法；开展了CFRP加固锈蚀钢结构疲劳性能在腐蚀环境下的耐久性研究，明确了CFRP加固锈蚀钢结构疲劳性能在腐蚀环境下的劣化机理，提出了CFRP加固锈蚀钢结构在腐蚀环境下的疲劳寿命退化模型。项目执行期间，项目组成员在《Construction and Building materials》、《Engineering Structures》、《Journal of Constructional Steel Research》、《Composite Structures》、《Thin-Walled Structures》、《Steel and composite structures》以及《材料导报》等国内外期刊上发表论文18篇，其中SCI检索14篇，EI检索4篇，研究成果进一步完善我国既有钢结构加固设计与评估理论，为我国土木工程灾害防御提供技术支持。