火灾下钢管混凝土叠合柱-RC梁平面框架内力重分布

Internal forces redistribution in plane frame with concrete-filled steel tube reinforced composite column and reinforced concrete beam in case of fire

火灾下钢管混凝土叠合柱-RC梁平面框架结构会产生膨胀变形.由于框架梁、柱的相互约束作用,框架结构不能自由膨胀变形,结构中发生内力重分布,影响框架结构的耐火性能.建立钢管混凝土叠合柱-RC梁平面框架有限元模型,用现有相关试验数据对有限元模型进行对比验证.利用该有限元模型在荷载和ISO-834标准升温作用下对钢管混凝土叠合柱-RC梁平面框架结构的内力重分布进行分析,并进行柱火灾荷载比和梁火灾荷载比不同作用下框架结构内力重分布的参数分析.研究表明:框架结构特征截面处内力变化剧烈;柱火灾荷载比和梁火灾荷载比对框架结构内力重分布产生显著影响,火灾作用下框架节点处梁端弯矩最大值约为常温值的3.8倍,应加强结构节点设计.

In case of fire, expansion deformation may occur in a framed structure with concrete-filled steel tube reinforced composite column and RC beam, but the framed structure can not implement freely the expanding deformation due to the mutual restriction of the column and reinforced and the redistribution of internal force occurs in the framed structure, affecting the fire resistance performance of the framed structure. A finite element model of plane framed structure with concrete-filled steel tube reinforced composite (CFSTRC) column and RC beam was established and it was validated with relevant test data. The internal force redistribution of the plane frame structure was analyzed under the load and ISO-834 standard temperature rise and the parametric analysis of the internal force redistribution of the frame under different column-to-fire load ratio and the beam-to-fire load ratio was also carried out. The investigation result showed that the internal forces would change greatly at the characteristic section of the framed structure, the column-to-fire load ratio and the beam-to-fire load ratio would have a significant influence on the internal forced redistribution of the framed structure, the maximum bending moment at the joint of the frame would be about 3.8 times of that at normal temperature of beam end in joint in case of fire, so that the design of the joint of the structure should be strengthened.