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通过对7根高温后钢筋混凝土短柱试件和1根常温对比试件的拟静力试验,研究受火时间、轴压比和剪跨比对火灾后钢筋混凝土短柱的破坏形态、受剪承载力、骨架曲线、刚度退化、延性比、滞回耗能等的影响。利用有限元程序计算了高温后截面混凝土抗压强度的平均折减系数,提出了四周受火后钢筋混凝土柱受剪承载力的计算方法。研究结果表明:高温后短柱的受剪承载力随受火时间的增加、剪跨比的增大而减小;剪跨比对受火前后受剪承载力影响变化的程度相差较小;高温后短柱的受剪承载力先随轴压比的增大而增大,但当轴压比增大至界限轴压比后,受剪承载力反将降低,且高温后柱的界限轴压比较未受火时有减小趋势;提出的高温后钢筋混凝土柱受剪承载力计算式具有一定的安全保证率,可用于火灾后该类构件受剪性能的损伤评定。
Through the quasi-static tests of seven high-temperature reinforced concrete short column specimens and one normal temperature contrast specimen, the failure modes of reinforced concrete short columns subjected to fire by time, axial compression ratio and shear-span ratio were studied. Bearing capacity, skeleton curve, stiffness degradation, ductility ratio, hysteresis energy consumption and so on. The average reduction coefficient of compressive strength of concrete after high temperature was calculated by finite element program and the calculation method of shear strength of reinforced concrete columns after fire for 4 weeks was put forward. The results show that the shear bearing capacity of short column increases with the increase of fire time and the shear span ratio increases, but the difference of shear span ratio is less affected by the shear strength before and after fire. The shear bearing capacity of the rear short column firstly increases with the increase of the axial compression ratio, but when the axial compression ratio increases to the limit axial compression ratio, the shear bearing capacity will decrease, and the critical axial compression Compared with no fire, it tends to decrease. The calculated formula of shear strength of reinforced concrete columns after high temperature has a certain safety guarantee rate, which can be used to evaluate the shear damage of such members after fire.