钢管混凝土叠合柱-钢筋混凝土梁平面框架耐火性能有限元分析

FEA on CFSTRC column-reinforced concrete beam plane frames subjected to fire

在合理考虑钢与混凝土之间的相互作用和选取正确的材料本构关系的基础上,建立钢管混凝土叠合柱-钢筋混凝土梁框架热-力耦合作用的有限元分析模型,并与现有相关试验数据进行对比,有限元分析结果与试验结果吻合良好;基于该有限元分析模型,对钢管混凝土叠合柱-钢筋混凝土梁平面框架在ISO-834标准火灾下的温度分布以及框架的工作机理进行分析,研究钢管混凝土叠合柱-钢筋混凝土梁平面框架在不同梁火灾荷载比下的变形规律和火灾作用过程中平面组合框架不同位置截面的内力变化。结果表明:钢管混凝土叠合柱-钢筋混凝土梁框架柱节点区的温度低于柱中部的温度,混凝土梁板对节点区柱截面温度分布有保护作用;不同梁火灾荷载比下,钢管混凝土叠合柱-钢筋混凝土梁框架均因梁跨中挠度变形速率过大而发生破坏,框架达到耐火极限,且随着梁火灾荷载比的增加,框架耐火极限减小;在火灾作用下,叠合柱中核心钢管混凝土承担大部分轴力。

On the basis of reasonable consideration of interaction and selection the correct material constitutive relation,a thermal-mechanical coupling effect finite element analysis model of CFSTRC columns-reinforced concrete beam planner frame was established. Some existing test results were used to verify the proposed finite element model.The temperature distribution and the working mechanism of CFSTRC column-reinforced concrete beam plane frames were analyzed under the ISO-834 standard fire. The influence of beam load ratio was investigated,and the internal force development in sections at different locations of plane frame under fire was simulated. The results show that in CFSTRC column-reinforced concrete beam plane frames temperature at beam-column joint regions is below the temperature at middle regions of columns. The beam-slab can limit the temperature distribution at beam-column joint regions. The mid-span deflection rate of frame beam is too large and causes damage under different beam load ratios that makes the frame reach fire endurance. With the increase of beam fire load ratio,the frame fire resistance decreases. The core concrete filled steel tubes in CFSTRC columns mainly carry axial force in fire.