混凝土及预应力混凝土结构抗火研究现状与展望

为拓展混凝土及预应力混凝土结构抗火的研究思路与方法,论述了普通钢筋、预应力筋、混凝土等结构材料的抗火性能,凝炼了混凝土及预应力混凝土结构构件的抗火性能,介绍了火灾后混凝土结构加固修复技术,指出了混凝土及预应力混凝土结构抗火研究中存在的一些问题,展望了其发展趋势.分析表明:混凝土高温爆裂临界温度随强度变化而变化,掺钢纤维或聚丙烯纤维可有效防止混凝土火灾下爆裂;合理考虑名义拉应力和混凝土强度影响的爆裂判别方法,可有效降低火灾下预应力结构混凝土爆裂风险;混凝土及预应力混凝土结构应满足火灾时不爆裂、火灾下不坍塌、火灾后可修复的抗火设计目标;火灾下防爆裂混凝土合理纤维掺量、混凝土及预应力结构构件高温爆裂机理及预测模型、活性粉末混凝土(RPC)高温爆裂规律、RPC热-力耦合本构关系及其结构构件抗火性能、温度-荷载路径对结构构件高温性能的影响、高层混凝土结构和地下空间结构抗火性能等方面应予关注.

Progress and prospect of fire resistance of reinforced concrete and prestressed concrete structures

In this chapter, the fire resistance of reinforced concrete and prestressed concrete structures are outlined to expend further research. The progress and prospect in fire resistance of reinforced concrete (RC) structures and prestressed concrete(PC) structures and its repair technology after fire is presented, and some issues that still need to be investigated are discussed. The progress mainly includes mechanical properties of materials at elevated temperatures, fire resistance of RC and PC structures, and fire-induced spalling of concrete. The results show that spalling critical temperature of concrete varies with compressive strength of concrete. Adding steel fibers or polypropylene (PP) fibers is able to prevent fire-included spalling of concrete effectively. The criteria considering nominal stress of concrete and concrete strength is effective for judging fire-induced spalling, which is capable for reducing the possibility of fire-induced spalling of concrete in PC members. The requirements that concrete structures will not collapse or spalling during fire and can be repaired after fire should be satisfied in fire safety design. Rational fibers dosage to prevent fire-included spalling of concrete, fire-included spalling and its prediction model on RC and PC members, fire-induced spalling of RPC, temperature-stress coupling strain-stress relation of RPC and fire resistance of RPC members, effect of force-temperature paths on behaviors of structures and members, fire resistance of high-rise buildings and underground structures are the main problems which need to be studied in the future.