火灾升降温模式对高温后钢筋混凝土轴压力学性能影响的试验研究

为研究实际火灾与标准火灾对高温全过程作用后钢筋混凝土力学性能的影响程度,进行了6根大尺寸钢筋混凝土短柱经历不同火灾模式的高温全过程作用后轴压力学性能试验。选择一典型住宅房间,根据欧洲规范得到了模拟火灾温度-时间曲线,利用等效曝火时间方法获得等效标准火灾,考察火灾模式、轴压比对高温全过程作用后钢筋混凝土承载力、刚度和延性的影响规律。试验结果表明:随着轴压比(n0.4)增大,高温后剩余承载力、刚度和延性损伤程度降低;火灾升降温模式影响显著。根据等能量法进行的火灾试验结果和模拟实际火灾试验结果吻合较好,而等面积法过于保守。建议相关规范采用基于能量的等效曝火时间方法进行抗火设计和火灾后剩余力学性能评估。

Experimental Study of the Effect of Fire Mode on Axial Compression Mechanical Properties of RC after Exposure to Entire Fire Process

In order to investigate the effect of whole high temperature process of actual fire and standard fire on the mechanical properties of reinforced concrete,axial compression mechanical property experiment was carried out for 6 large-scale short RC column subjected to whole high temperature process of different fire modes.Selecting a typical residential room,according to European norms,the temperature-time curve of simulated fire was obtained;using equivalent exposure time method,the equivalent standard fire was obtained.Then,the effect of fire mode and axial compression ratio on the residual compressive strength,axial stiffness and ductility of RC stub columns were explored.Experimental results show that with the increase of axial compression ratio (n ＜0.4),residual compressive strength,axial stiffness and ductility of RC stub columns decreased,and fire modes have significant effect on mechanical behavior.Experimental results obtained according to equivalent energy method are in good agreement with that obtained from simulated actual fire.Equiavalent area method is found to be conservative.It is recommended that the equivalent exposure time method based on energy should be used to make the fire design and evaluate residual mechanical behavior after fire.