轴心受压方形截面钢管混凝土叠合柱耐火性能

为探讨轴心受压方形截面钢管混凝土叠合柱的耐火性能，对4根轴心受压方形截面钢管混凝土叠合柱进行了试验研究，并对火灾荷载比、截面含管率和截面边长等对耐火性能的影响进行了有限元分析.研究结果表明:当火灾荷载比减小、截面含管率和截面边长增大时，火灾作用下试件的轴向膨胀变形增大，轴向压缩变形减小；在相同的升温曲线和火灾时间作用下，截面边长增大时，柱内温度降低；含管率变化对柱内温度场影响较小.火灾荷载比、截面边长和长细比是影响轴心受压方形截面叠合柱耐火性能的主要因素；含管率、纵筋配筋率和材料强度变化对轴心受压方形截面叠合柱耐火性能的影响较小. 

Fire Resistance Performance of Concrete-Filled Steel Tube RC Square Columns under Axial Loading

In order to research the fire resistance performance of concrete-filled steel tube reinforced concrete (CFSTRC) square columns under axial loading, fire resistance tests of four CFSTRC square columns subjected to axial load were conducted. The effects of axial loading level, steel tube area ratio and side length of cross section on the fire resistance performance were discussed by numerical simulations. The research results show that axial expansion deformations of CFSTRC square columns increase and their axial compression deformations decrease with minishing of axial loading level and raisings of steel tube area ratio and side length of cross section under fire exposure. Under the same elevated temperature curve and fire exposure time, a large side length of cross section will result in low temperature inside the square columns, and steel tube area ratio has a slight influence on the temperature distribution of CFSTRC square columns. Axial loading level, side length of cross section and slenderness ratio have great effects on the fire resistance performance of CFSTRC square columns under axial loading, while steel tube area ratio, reinforcement ratio and material strength have a slight influence on the fire resistance performance.