中文摘要：

将钢筋混凝土异形柱沿高度划分为若干小段,假定每一小段内各截面的曲率线性变化,结合虚梁法和结构截面在力和温度作用下的非线性增量有限元分析方法,提出了钢筋混凝土异形柱高温下基于虚梁法的数值分析方法,同时建议了高温下每一增量步内混凝土和钢筋应力-应力应变点位置的确定方法。编制了相应的程序RCSSCF,程序考虑了轴力的二阶效应,程序的有效性得到试验结果的验证。研究表明：基于虚梁法的数值分析方法计算的耐火极限总体上略小于基于变形假定的数值分析方法计算的耐火极限。

英文摘要：

Reinforced concrete specially-shaped column is divided into several segments along its height. The sectional curvature is supposed to vary linearly in each segment. Combining the conjugate beam method and the nonlinear incremental finite element analytical method of reinforced concrete section under force and temperature, a numerical analytical method for specially-shaped column subjected to high temperature is proposed. Moreover, a method for determining the position of the point in the stress and stress-strain curves of concrete and steel bar in every increment step under elevated temperature is suggested. A corresponding computer program RCSSCF is developed and the second-order effect of axial forces is considered in the program. The reliability of the program is validated using test results. Studies show that the fire resistance calculated using the numerical method based on the conjugate beam is slightly less than the results calculated using the numerical method based on deformation assumption on the whole.