混凝土结构抗火研究综述与建议

Review and suggestion on fire resistance research of reinforced concrete structures

为了促进混凝土结构抗火研究的发展,从火灾温度场发展过程、混凝土结构抗火性能与抗火设计、火灾后结构损伤评估与加固修复、混凝土结构抗火性能提高方法等4个方面出发,总结混凝土结构抗火研究成果,指出研究中存在的问题并展望了其发展趋势。从空气、结构温度场2个方面归纳了火灾温度场研究方法,总结不同参数对混凝土材料、构件、结构高温性能的影响规律,分析现有混凝土结构抗火设计方法的应用以及其优点和不足,梳理火灾后结构损伤评估流程,分析火灾后实际工程损伤评估与加固修复案例,并对现有火灾后结构损伤检测和维修加固方法进行总结,最后,从材料及构造2个方面总结提高混凝土结构抗火性能的方法。研究表明:高温下混凝土结构力学性能劣化严重,掺加纤维、调整原材料配合比和应用合理构造措施可提高混凝土结构抗火性能,掺聚丙烯纤维可有效避免高性能混凝土高温爆裂。后续应重点研究高温下大空间混凝土结构温度场分布,材料高温性能随机性对混凝土构件力学性能的影响规律,不同温度-荷载路径及反复升降温对结构和构件高温性能的影响,科学的混凝土结构火灾损伤评估体系,结构抗火可靠度设计理论研究和高性能混凝土结构抗火设计方法等方面。

To promote the development of research of fire resistance of concrete structures, the four aspects of the development process were systematically summarized. Accordingly, the development of the temperature field of fire, fire resistance performance and fire resistance design of concrete structures, damage assessment and repair reinforcement of structures after fires, improvement of the fire resistance of structures, and some issues for each aspect that still need to be investigated were discussed, and the development trend of the research was also prospected. Among them, the research methods of the fire temperature field were summarized from the perspectives of air and structural temperature fields. The effects of different parameters on the high-temperature resistance performance of concrete materials, members, and structures were also summarized. Further, the application, advantages, and disadvantages of existing fire-resistance designs for concrete structures were analyzed, and the general process of structural damage assessment after a fire was examined. Engineering damage assessment and reinforcement repair cases after fires were also analyzed, and existing detection and repair methods after fires were summarized. Finally, methods for improving the fire resistance of structures were listed in terms of materials and construction. The results show that the mechanical properties of concrete structures deteriorate seriously at high temperatures. Adding fibers, adjusting raw materials, and construction measures can improve structural fire resistance. Further, adding polypropylene fibers can effectively prevent spalling of high-performance concrete. The following main subjects need further study, such as the temperature field distribution of large concrete structures under high temperature, the influence of the randomness of a material's high-temperature performance on mechanical properties of members, the influence of different temperature load paths, the effects of repeated lifting and lowering temperatures on the high-temperature performance of structures and members, the establishment of a scientific evaluation system for structures subjected to high temperatures, a theoretical study on structural fire resistance reliability design, and a high-performance concrete structure fire resistance design method.