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通过6根未受火和12根明火试验后的方钢管钢筋混凝土轴压短柱静力试验,研究了升温时间和配筋率对受火后方钢管钢筋混凝土短柱剩余承载力、刚度和延性的影响;对于升温时间30 min和60 min轴压短柱,分别测量了升温过程中关键位置的温度分布情况。试验结果表明:与常温轴压短柱相比,升温30 min且配筋率分别为1.45%及3.26%的轴压短柱,其剩余承载力、轴压刚度和延性分别降低13.4%及5.4%、20.8%及24.3%和31.9%及44.0%;对于升温60 min轴压短柱,其剩余承载力、轴压刚度和延性分别降低23.3%及12.8%、37.5%及39.1%和52.5%及61.5%。在试验基础上,结合GB50936—2014《钢管混凝土结构技术规范》给出了火灾后方钢管钢筋混凝土轴压短柱剩余承载力计算式,其计算结果与试验结果吻合较好。
Through the static tests of 6 uncoiled and 12 open flame tests of square steel tubular stub columns, the effects of heating time and reinforcement ratio on the residual bearing capacity, stiffness and ductility of reinforced concrete short columns after fire are studied. . The temperature distributions at key locations during heating were measured separately for the axial compression short columns with heating time of 30 min and 60 min. The experimental results show that the residual bearing capacity, axial compressive rigidity and ductility are reduced by 13.4% and 5.4% respectively, compared with those of the short-time column under axial compression, when heated for 30 min and the reinforcement ratios are 1.45% and 3.26%, respectively. , 20.8%, 24.3%, 31.9% and 44.0%, respectively. The residual bearing capacity, axial compression stiffness and ductility decreased by 23.3% and 12.8%, 37.5% and 39.1% and 52.5% and 61.5% %. On the basis of the experiment and the combination of GB50936-2014 “Technical Specifications of Concrete-filled Steel Tube”, the formulas for calculating the residual bearing capacity of the concrete-filled steel tubular short columns after fire are given. The calculated results are in good agreement with the experimental results.