中文摘要：

利用SAFIR程序,进行了约束混凝土柱升降温全过程的弯矩分析,考察了截面边长、配筋率、升温时间、转动约束刚度比等参数对ISO834标准升降温过程作用下约束混凝土柱半高处弯矩的影响规律,并与单调升温时的相应规律进行了对比.通过对192种工况的计算分析,给出了该类构件半高处弯矩变化系数的实用计算方法.研究结果表明：升降温过程中,无转动约束柱的半高处弯矩变化系数呈现出先逐渐增大再缓慢降低后渐趋平缓的变化趋势,明显不同于单调升温时一直增大的现象;升降温过程中,转动约束柱的半高处弯矩变化系数首先迅速减小继而缓慢降低后渐趋平缓,单调升温时的变化趋势与此基本类似.所提出的方法具有较高的精度,公式计算值与程序计算值的相关系数达0.992.

英文摘要：

With the help of SAFIR,the bending moment of reinforced concrete（RC） columns in the heating and cooling process is analyzed,and the influences of such parameters as sectional dimension,reinforcement ratio,heating time and rotational restraint stiffness ratio,etc.on the bending moment at the mid-height of restrained concrete column exposed to the ISO834 standard fire with cooling phase are investigated.The results are then compared with those corresponding to the ISO834 standard fire without cooling phase.Moreover,based on the simulation of 192 cases,a practical calculation method for the bending moment at the mid-height of column exposed to fire with cooling phase is proposed.It is thus shown that（1） the enhancement coefficient of the bending moment at the mid-height of axially-restrained column first increases and then gradually decreases till to a constant in the fire with cooling phase,which is quite different from that in the fire without cooling phase;（2） the enhancement coefficient of the bending moment at the mid-height of axially-and-rotationally-restrained column first rapidly decreases and then gradually decreases till to a constant in the fire with or without cooling phase;and（3） the proposed calculation method is of high accuracy,and the correlation coefficient between the calculated results and the simulation ones reaches 0.992.