高温下钢筋和混凝土强度随机性对柱耐火极限的影响

引入具有不同概率水平的钢筋/混凝土相对高温强度——温度关系，在其他参数一定的情况下，通过大量计算分析，揭示了钢筋/混凝土相对高温强度的随机性对柱耐火极限的影响趋势。研究结果表明：①直接选用钢筋/混凝土相对高温强度随温度变化的均值曲线进行计算，可近似得到柱耐火极限的均值；②钢筋/混凝土相对高温强度的变异系数的变化范围和最大值明显大于柱耐火极限的变异系数；③随着荷载偏心率增加，钢筋相对屈服强度随温度变化的随机性对柱耐火极限的影响不断增强，而混凝土棱柱体相对抗压强度随温度变化的随机性对柱耐火极限的影响却不断减弱；④柱耐火极限服从正态分布。

Influence of random characteristics of strengths of concrete and steel bar at high temperature on fire resistance of column

Based on the relationships with different probabilistic levels between relative strengths of steel bar/concrete and high temperature, the influence of random characteristics of relative strengths of steel bar/concrete at elevated temperature on fire resistance of axially- and eccentrically-loaded columns is examined by extensive numerical analyses. Simulation results show that: (a) the mean value of column fire resistance can be obtained approximately through calculation using the mean curves of relative strengths of steel bar/concrete via temperature; (b) the maximum value of variance coefficients of relative strengths of steel bar/concrete at high temperature is larger than that of column fire resistance; (c) with an increasing of load eccentricity ratio, the effect of random characteristics of relative yield strength of steel bar at high temperature on column fire resistance increases, but the influence of random characteristics of relative compressive strength of concrete at high temperature on column fire resistance decreases; and (d) column fire resistance is in accordance with the Normal-distribution.