火灾下钢筋混凝土双向板有限元分析

Finite element analysis of reinforced concrete bi-directional slab under fire

为研究钢筋混凝土双向板耐火极限,以配筋率和受火时间为变量,对比分析钢筋混凝土双向板因热膨胀引起的挠度变化以及板内升温过程的试验值与模拟值,验证有限元模拟的准确性,并以此为基础,增加受火时间,探究钢筋混凝土双向板耐火极限。结果发现:火灾作用下,增大配筋率对钢筋混凝土双向板温度发展无明显影响,但能有效降低其挠度发展,在达到耐火极限时钢筋混凝土双向板最先失去隔热性。故在火灾作用下,当钢筋混凝土双向板跨度较小时,其耐火极限以是否失去隔热性为判断依据。

In order to study the fire resistance limit of reinforced concrete bi-directional slabs and taking the reinforcement rate and fire exposure time as the variavlbes,the experimental values of deflection changes due to thermal expansion and the warming process inside the slab were compared with the simulated values to verify the accuracy of finite element simulation,and based on this,the fire resistance limit of reinforced concrete bi-directional slabs was investigated by increasing the fire exposure time.The results showed that when exposed to fire,increasing the reinforcement rate has no significant effect on the temperature development of reinforced concrete bi-directional slabs,but can effectively reduce its deflection development,and the reinforced concrete bi-directional slabs are the first to lose their thermal insulation at the time of reaching the fire resistance limit.Therefore,when exposed to fire,if the span of the reinforced concrete bi-directional slab is small,its fire resistance limit should be judged according to whether it loses thermal insulation.