火灾后型钢混凝土构件抗弯和轴压刚度计算方法

Calculations on the flexural and axialstiffnesses of steel reinforced concrete members after exposure to fire

火灾后构件的截面刚度是进行结构内力分析的基础,也是进行火灾后力学性能评估和抗震分析的关键指标。为计算火灾后型钢混凝土柱初始、使用阶段的抗弯和轴压刚度,该文采用火灾后型钢混凝土柱力学性能的有限元分析模型对常用参数范围内影响火灾后型钢混凝土柱初始、使用阶段的抗弯和轴压刚度的参数进行了参数分析。结果表明:升温时间、截面周长和截面含钢率是主要影响因素。在参数分析的基础上,给出了相应的实用计算公式,结果可为型钢混凝土柱火灾后的力学性能分析提供参考。

The sectional stiffnesses of members after exposure to fire are needed for internal force analyses,so they are a key parameter for post-fire evaluations and seismic analyses.The initial and service flexural and axial stiffnesses were calculated using a finite element analysis（FEA）model for steel reinforced concrete（SRC）columns after exposure to fire to analyze the effects of commonly used parameters.The results of the parametric study show that the heating time,the sectional perimeter and the sectional steel ratio are the main factors affecting the selected stiffness.Simplified formulas for the initial and service flexural and axial stiffnesses after a fire were then developed for mechanical analyses of SRC structures after exposure to fire.