火灾后混凝土短柱的滞回性能和损伤评定

Hysteretic Behaviors and Damage Assessment of Concrete Short Columns after Fire

基于7根明火加热后钢筋混凝土短柱和1根未受火的对比试件的拟静力试验结果,分析受火时间、轴压比和剪跨比对火灾后钢筋混凝土短柱滞回性能的影响情况.结合强度退化分析各试件的损伤发展过程,采用Park损伤模型对受火后短柱和未受火的对比试件的抗震性能进行损伤评定,提出一种能反映火灾高温对柱式构件抗震性能损伤影响加大的评价指标.研究结果表明:火灾后钢筋混凝土短柱在低周往复荷载作用下的滞回曲线和滞回规则与未受火对比件的相似,但受火后滞回环的稳定性较未受火的差;钢筋混凝土短柱的累积滞回耗能随着受火时间的增加,轴压比的减小,以及剪跨比的减小而减小;同一位移角下的强度退化随着受火时间的增加,轴压比的增大,以及剪跨比的增大而加快.此外,Park损伤评价模型对受火前后钢筋混凝土短柱的抗震性能损伤指数均存在超前估计的不足.

Based on the pseudo-static test data of seven reinforced concrete （RC） short columns after fire and one cont- rastive unfired specimen, the effects of fire exposure time, axial compressive ratio and shear span ratio on the hysteretic behaviors were analyzed. Combining strength degradation analysis which reflects the damage development process of the specimens, the Park＇s damage model was adopted to assess the damage of aseismic behavior of specimens unfired and after fire. An assessment index of fire on aseismic performance damage was proposed. The results show that： the hysteretic curves and hysteretic rules of RC short columns after fire are similar to the column unfired, but the stability of RC short columns after fire is much poorer than the eolunm unfiredl The accumulated hysteretic dissipated energy of short columns decreases with increasing fire exposure time and with decreasing the axial compressive ratio and the shear span ratio. Un- der the same displacement angle, the strength degradation increases with increasing fire exposure time, the axial compres- sive ratio and the shear span ratio. There exist some disadvantages in Parkts damage model to estimate damage index of the aseismic behavior of reinforced concrete short columns before and after fire.