方钢管混凝土柱-钢梁框架耐火性能分析

Fire resistance analysis of square concrete-filled steel tubular column to steel beam frames

研究方钢管混凝土柱-钢梁框架结构的耐火性能。基于有限元方法,分析了GB/T 9978(同ISO-834)加热条件下,带有混凝土楼板的方钢管混凝土柱-钢梁单向螺栓连接框架结构的温度分布、耐火时间和破坏模式,并对有限元模拟结果进行了试验验证,在试验结果基础上采用有限元方法分析了方钢管混凝土柱构件与方钢管混凝土框架柱的耐火极限差异。研究结果表明:与方钢管混凝土框架柱的其他区域相比,方钢管混凝土框架柱节点区的温度相对较低;根据本文建议的框架结构判定准则,当单向螺栓节点连接可靠,随着作用在柱和梁上荷载水平的变化,柱破坏模式和梁破坏模式是方钢管混凝土柱-钢梁框架的主要破坏模式;当框架梁上不施加荷载,只对框架柱起到约束作用,其他条件相同时,方钢管混凝土框架柱的耐火极限大于两端铰接柱构件的耐火极限,但小于一端固接一端铰接支撑柱构件的耐火极限。

The fire resistance performance of square concrete filled steel tubular(CFST) column to steel beam frames is studied. Based on the finite element(FE) method, the FE model is established to analyze the temperature field, fire resistance time, and failure mode of the square CFST column to steel beam frame structure with reinforced concrete slab and blind bolted connections under the GB/T 9978(identical with ISO-834) standard heating curve. The results of the finite element simulation are verified with experimental results. Based on experimental results, the difference of fire resistance between square CFST column members and square CFST frame columns is analyzed with FE method. The analysis results show that compared with other region of square CFST frame columns, the temperature in the joint region of square CFST frame columns is relatively lower. According to the frame structure judgment criterion proposed in this paper, when the blind bolt connection was reliable, the failure modes of square CFST column to steel beam frame reaching the fire resistance limit are mainly column failure mode and steel beam failure mode with the changing of load level acting on columns and beams. When no load is applied on the frame beam, it only restricts the frame column, and when other conditions are the same, the fire resistance limit of the square CFST frame column is greater than that of the hinged column member at both ends, but it is less than the fire resistance limit of one end fixed and one end hinged column member.