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对混凝土轴压柱抗火计算所用荷载比与其常温设计荷载比的换算关系进行了推导和分析,分别针对耐火等级一级和二级情况下的柱耐火极限要求,给出了四面受火轴压方柱满足目标抗火可靠指标的最小截面取值。研究表明:①常温设计荷载比大致为抗火计算所用荷载比的2～5倍,一般混凝土柱可近似取2.5倍;②荷载比小于0.2时,现行规范给出的300mm×300mm截面柱,在抗火可靠指标不小于目标抗火可靠指标的情况下可以满足二级耐火要求;③荷载比和耐火等级是影响轴压柱最小截面取值的主要因素。
The conversion relation between the load ratio and the design load ratio at normal temperature of the axial compression column was deduced and analyzed. According to the requirements of column fire resistance for the first and second level of refractory grade, Square column to meet the target fire reliability index of the minimum section value. The results show that: ① The load ratio at room temperature is about 2 ~ 5 times of the load ratio used in fire resistance calculation, and the average concrete column can be approximately 2.5 times; ② When the load ratio is less than 0.2, the 300mm × 300mm cross- Fire-resistant reliability index is not less than the target fire-resistant reliability index to meet the second-level fire resistance requirements; ③ load ratio and fire rating is the main factor affecting the minimum column axial compression column value.