相邻两面受火和三面受火混凝土矩形柱的耐火极限研究

FIRE RESISTANCE OF CONCRETE COLUMNS WITH RECTANGULAR CROSS SECTION SUBJECTED TO 2-ADJACENT-FACE AND 3-FACE HEATING

利用高温下钢筋混凝土柱基于虚梁法的数值模拟程序RCSSCF,分析了轴压比、计算长度、截面尺寸、荷载偏心率、配筋率和荷载角等参数对ISO834标准升温过程下相邻两面受火和三面受火钢筋混凝土矩形柱耐火极限的影响规律。针对不同轴压比、计算长度、截面尺寸、荷载偏心率、配筋率和荷载角等情况,共进行了9792种工况下相邻两面受火矩形柱的高温反应分析、11520种工况下三面受火矩形柱的高温反应分析。在计算结果的基础上,定量给出了相邻两面受火和三面受火钢筋混凝土矩形柱耐火极限的实用计算方法。研究表明:a)严格控制轴压比是提高矩形柱耐火极限的有效措施;b)荷载角对相邻两面受火和三面受火矩形柱的耐火极限影响较大;c)随着轴压比的增大,相邻两面受火和三面受火矩形柱耐火极限的差异减小。

Using a numerical program RCSSCF, this paper studies the influence of several parameters, such as axial load ratio, effective length, sectional dimension, load eccentricity ratio, reinforcement ratio and load angle, on the fire resistance of reinforced concrete columns with rectangular cross section subjected to the ISO834 standard fire and 2-adjacent-face, or 3-face heating. 9792 hypothetical cases of columns subjected to 2-adjacent-face heating, and 11520 hypothetical cases of columns subjected to 3- face heating are selected for fire response analysis. Different axial load ratios, effective lengths, cross section dimensions, load eccentricity ratios, and load angles are considered in the analysis. Based on the simulation results, a practical method is proposed for calculating the fire resistance of reinforced concrete columns with rectangular cross section subjected to 2-adjacent-face heating, or 3-face heating. The simulation results indicate that： a） reducing the axial load ratio is an effective measure to improve the fire resistance of columns with rectangular cross section, b） the influence of load angle on the fire resistance of columns with rectangular cross section subjected to 2-adjacent-face heating, or 3-face heating is significant, c） the difference between the fire resistance of the columns with rectangular cross section subjected to 2-adjacent-face heating and that of the columns subjected to 3-face heating decreases with the increasing of axial load ratio.