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为分析震后火灾环境下混凝土结构的反应,试验设计了3榀足尺单层单跨框架结构,以低周反复水平荷载试验模拟地震动,以框架梁、柱裂缝宽度ω为损伤指标,试件KJ1历经损伤ω=0.5 mm后进行火灾试验,KJ2历经损伤ω=0.1 mm后进行火灾试验,试件KJ3作为对比试验无损伤,直接进行火灾试验。从3榀框架结构的裂缝变化规律、框架柱轴向变形、截面温度场分布、承载力退化等方面进行了对比分析。试验结果表明:损伤后混凝土材料的热传导性能提高,相应截面所经历的最高温度也增高;框架结构的高温变形恢复能力变差,梁截面承载力下降幅度比柱截面大。最后提出了损伤指标与结构抗火性能退化之间的量化关系。
In order to analyze the response of concrete structures under fire environment after earthquake, three-foot full-scale single-story and single-span frame structures were designed and tested. The ground motion was simulated by low-cycle repeated horizontal load test. KJ1 after the damage of ω = 0.5 mm after the fire test, KJ2 after the damage ω = 0.1 mm after the fire test, the specimen KJ3 as a comparative test without damage, the direct fire test. The contrastive analysis of cracks in 3 榀 frame structures, axial deformation of frame columns, distribution of temperature field in cross section and degradation of bearing capacity were carried out. The experimental results show that the thermal conductivity of concrete after damage increases, and the maximum temperature experienced by the corresponding section also increases. The high-temperature deformation recovery of the frame structure deteriorates, and the bearing capacity of the beam section decreases more than the section of the column. Finally, the quantitative relationship between damage index and structural fire resistance degradation was proposed.