钢筋混凝土受压构件防火性能的非线性分析

Non-linear analysis of fire resistance of RC compression members

通过对Fourier热传导方程的数值求解 ,推导出了钢筋混凝土矩形截面在不同受火条件下温度场分布 .将得到的温度数据结果自动传递到非线性有限元程序中 ,并采用考虑材料高温下徐变影响的钢材和混凝土随温度而不断变化的本构关系 ,对钢筋混凝土受压构件进行了受火时时间 -变形全过程曲线的计算 ,分析了混凝土受压构件在受火时的各种力学性能变化以及截面尺寸、混凝土保护层厚度、钢筋布置等不同参数对钢筋混凝土受压构件的防火承载力的影响 ,得到了钢筋混凝土受压构件在受火时的破坏特征是由荷载、高温下材料强度的下降和温度场不均匀分布等因素共同作用下的突然失稳破坏 .

By automatically inputting the temperature data, adapting the steel and concrete constitute relationships which vary with the temperature and including the effects of creep, a non-linear FE program is used for calculating the time-thermal stress historical curves. The behaviour of RC columns in fire is investigated and the effects of different parameters such as size, concrete cover, arrangement of reinforcing steel bars on the fire resistances of RC columns are analysed. It is concluded that the collapse of a column in fire is a sudden buckling caused by the combination of compression stress, the reduction in material strength due to high temperature and the eccentricity due to nonuniform temperature distribution. The results are in good agreement with those from Eurocode.