标题: 内灌混凝土箱型钢柱于火害下之行为
Behaviour of Concrete-Filled Steel Box Columns in Fire
作者: 林政亿
陈诚直
Lin, Jheng-Yi
Chen, Cheng-Chih
土木工程系所
关键字: 火害;内灌混凝土箱型钢柱;载重比;剪力钉;耐火时间;fire;concrete-filled steel box column;load ratio;shear stud;fire resistance
公开日期: 2016
摘要: 本研究采用实验方式与有限元素分析方法,探讨受轴向定载内灌混凝土箱型钢柱于火害下之构件行为与耐火性能,并依据研究成果提出内灌混凝土箱型钢柱耐火时间公式。实验规划4支试体进行耐火实验以瞭解试体断面温度分布、轴向变形与破坏模式,并探讨施加不同轴向载重(30%和60%试体极限强度)与有无配置剪力钉之试体参数对柱构件耐火性能的影响。有限元素分析为透过热传分析与考量温度影响之非线性结构分析模拟高温实验试体行为,进而探讨试体高温下钢柱与混凝土分别之变形行为与受力情况。利用数学模型采最小平方法拟合本研究与文献实验结果之下限值,以建立内灌混凝土箱型钢柱耐火时间公式。
实验结果显示,升温环境使内灌混凝土箱型钢柱温度逐渐增加,而构件温度增加造成其先产生轴向伸长变形后,再产生压缩变形直至破坏。破坏模式为柱压缩破坏,试体柱钢板多处局部挫屈变形且混凝土碎裂。试体载重比参数相较剪力钉参数明显影响柱构件轴向变形行为与耐火时间。分析结果显示,有限元素分析模型可合理预测试体受火害中温度分布与变形趋势。分析可见试体于火害期间会产生轴向与横向变形,亦可用以计算火害期间箱型钢柱与混凝土各别之承载。最后,本研究提出内灌混凝土箱型钢柱耐火时间公式,可保守且合理的预测耐火时间,期有助益于防火性能设计。
This study was conducted experimentally and numerically to explore the fire resistance of axial-loaded concrete-filled steel box columns exposed to fire. According to the test results, a fire resistance formula was proposed. Four specimens were designed and tested to study the temperature distribution on cross section, the axial deformation, and the failure mode, and to investigate the effects of load ratio (30% and 60% of the ultimate strength) and shear stud on fire resistance. Finite element analyses were performed for both heat transfer and nonlinear static analyses and used to simulate the fire behavior of the specimens, and further to explore the individual deformation and the load-carrying capacity of the steel box column and the concrete. The fire resistance formula was established by means of least squares regression to fit lower bound of the test results of this study and literature.
The test results showed that the specimens axially elongated due to the temperature increase when the specimens were exposed to temperature increase. Next, the specimens turned to shortening till failure. The failure mode was the compressive failure of the column, including shortening of the specimens, bulge of column steel plate, and crushing of concrete inside the steel box. Compared to the shear stud, the load ratio highly affected the axial deformation and the fire resistance. The analytical results indicated that the analysis reasonably predicted temperature distribution on the cross section and the tendency of the axial deformation of the specimens. The analysis results also revealed that the axial and lateral deformation of the specimens subjected to fire. Moreover, the individual load-carrying capacity during the fire duration of the steel box and the concrete could be calculated. Finally, a fire resistance formula was proposed to predict the fire resistance of the concrete-filled steel square box columns. The formula can conservatively and reasonably predict fire resistance and will benefit the performance-based fire resistance design.
URI: http://etd.lib.nctu.edu.tw/cdrfb3/record/nctu/#GT079716803
http://hdl.handle.net/11536/138744
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