论文部分内容阅读
火灾作用下混凝土构件的承载能力总体不断下降且具有明显随机性,采用抗火可靠指标可较好地评估构件的火灾安全性。本文针对混凝土轴压柱的高温承载能力极限状态,考虑材料强度变异性导致的柱高温极限承栽力的随机性,以及高温下柱荷栽效应组合的随机性,采用JC法计算给出了ISO834标准升温曲线作用下不同受火时间对应的柱抗火可靠指标,讨论了主要参数对该可靠指标的影响规律;并根据我国现行建筑防火规范,通过分析和参照对比,初步提出了混凝土轴压柱抗火可靠指标的目标建议值。研究认为:(1)截面尺寸越小,柱抗火可靠指标随受火时间增加而下降的速率越快;(2)现行规范给出的截面(200×200)mm、(240×240)mm、(300×300)mm 3种柱在各自耐火极限时刻的抗火可靠指标较为接近,但截面(370×370)mm柱的抗火可靠指标却明显偏低;(3)混凝土轴压柱的目标抗火可靠指标建议取为1.6。
The carrying capacity of concrete members under fire generally declines continuously and has obvious randomness. The fire safety index of components can be evaluated well by using fire-resistant reliability indexes. In this paper, according to the limit state of high temperature bearing capacity of concrete axial compression column, considering the randomness of the ultimate bearing capacity of the column under high temperature and the randomness of the combined effect of column loading under high temperature, According to the current building fire safety regulations in our country, through the analysis and reference comparison, the paper puts forward the concrete axial compression column Targets Recommended Values for Fire Resistance. The results show that: (1) The smaller the cross section size, the faster the column reliability index declines with the increase of fire time; (2) The cross section (200 × 200) mm, (240 × 240) mm (300 × 300) mm, the fire resistance reliability indexes of the three kinds of columns at the respective refractory limit moments are relatively close, but the fireproof reliability index of the section (370 × 370) mm column is obviously lower; (3) The target of anti-fire reliable indicator is taken as 1.6.