钢筋混凝土T形柱的耐火极限研究

Fire resistance of reinforced concrete columns of T-shaped cross section

利用数值模拟程序分析了荷载比、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标准升温过程下钢筋混凝土等肢T形柱耐火极限的影响规律。针对不同荷载比、计算长度、截面尺寸、荷载偏心率、配筋率和荷载角共5400种工况进行了四周受火时等肢T形柱的高温反应分析。在此基础上,定量给出了该类构件耐火极限的实用计算方法。研究表明:(a)严格控制荷载比是提高T形柱耐火极限的有效措施。(b)随着计算长度的增加,T形柱耐火极限近似呈直线降低。(c)当荷载偏心率在0和1.0之间变化时,T形柱耐火极限随荷载偏心率的增大而减小。当荷载偏心率在1.0和2.0之间变化时,荷载偏心率改变对T形柱耐火极限影响较小。(d)荷载角对T形柱耐火极限影响较大且影响规律较为复杂。

Analyses were performed to study the influence of several parameters, such as load ratio, effective length, section dimension, load eccentricity ratio, reinforcement ratio and load angle, on the fire resistance of reinforced concrete columns of T-shaped cross section exposed to the ISO834 standard fire. 5400 hypothetical cases of columns subjected to fire in all sides were selected for fire response analysis. Different load ratios, effective lengths, cross section dimensions, load eccentricity ratios, reinforcement ratios, and load angles were considered in the analyses. Based on the simulation results, a practical method is proposed for calculating the fire resistance of columns of T-shaped cross section subjected to fire in all sides. The simulation results indicate that： （a） reducing the load ratio is an effective measure to improve the fire resistance of columns of T-shaped cross section; （b） the fire resistance of columns of T-shaped cross section decreases linearly with the increase of effective length; （c） the fire resistance of columns of T-shaped cross section decreases significantly with the increase of load eccentricity ratio from 0.0 to 1.0, whereas varies only slightly for a load eccentricity ratio between 1.0 and 2.0; and （d） the influence of load angle on the fire resistance of columns of T-shaped cross section is significant and complex.