火灾作用后圆钢管混凝土柱荷载-位移滞回性能研究

火灾作用后,钢管混凝土柱的强度和刚度均会遭受损失,需进一步考察其抗震能力。本文介绍了7个火灾后圆钢管混凝土试件滞回性能试验研究,采用数值方法对荷载位移滞回关系曲线进行全过程分析,计算分析了轴压比、长细比、含钢率、钢材屈服极限、混凝土抗压强度、受火时间等参数对荷载位移关系骨架线的影响。研究结果表明,火灾作用后圆钢管混凝土柱滞回关系曲线形状饱满,无明显的捏缩现象,但试件的极限承载力和弹性刚度会有所降低。本文的研究成果可为火灾后该类结构的抗震修复加固提供参考。

Load-displacement hysteretic behavior of concrete filled CHS columns after exposure to ISO-834 standard fire

The load-carrying capacity and the stiffness of concrete filled circular hollow section (CHS)columns will decrease after exposure to fire, so it is necessary to assess the aseismic capacity of concrete filled steel tube (CFST) structure in seismic areas. This paper provided seven test data pertaining to the seismic behavior of concrete filled CHS columns after exposure to ISO-834 standard fire, and a numerical method was used to calculate the hysteretic lateral load (P) versus lateral displacement (Δ) relations. Based on the theoretical model, influences of the changing axial compression ratio(n), slenderness ratio (λ), steel ratio (α), yield strength of steel (f_y) and compressive strength of concrete (f_(cu)), fire duration time (t) on the lateral load versus lateral displacement skeleton curves were discussed. The results showed that the hysteretic curves of the beam-columns are in plump shapes, and have no significant pinch phenomenon after exposure to fire, but the ultimate load-carrying capacity and the elastic stiffness will decrease with the increase of the fire duration time. The achievements in this paper may be used to afford an approach to repair such structure with fire protection against earthquake after fire.