双钢管混凝土复合柱的耐火性能及参数影响分析

双钢管混凝土复合柱在普通钢管混凝土柱基础上设置了内部钢管，由于内管受到外层混凝土的高温保护，因此其耐火性能得到改善。文章通过精细化数值模拟方法对此类双钢管混凝土复合柱的耐火性能开展研究，全面分析了内管径厚比、外管径厚比、内外管直径比等参数的影响，并且对比分析了在相同的含钢率条件下不同截面组合型式（内圆外圆、内方外圆和内圆外方）双钢管混凝土短柱的耐火极限。结果表明：在直径不变时增大内钢管的厚度以及在厚度不变时增加内钢管的直径，都有利于耐火极限的提高；在保持整体含钢率不变的条件下，不同截面组合形式的双钢管混凝土柱耐火极限相差不大，但总体上双圆钢管混凝土短柱的耐火性能偏优；另外，双钢管混凝土复合柱的耐火性能比普通钢管混凝土柱有较大提高。

Fire resistance and parameters influence of concrete filled double steel tubular columns

Abstract: Double concrete-filled steel tubular composite column is provided with internal steel tube on the basis of ordinary concrete-filled steel tubular column. Because the inner tube is protected by outer concrete, its fire resistance will be improved. In this paper, the fire resistance of this kind of double steel concrete composite column is studied by refined numerical simulation method, the effects of internal diameter thickness ratio, external diameter thickness ratio and internal and external tubular diameter ratio are comprehensively analyzed, and the different section combination types (inner circle and outer circle, inner square and outer circle and inner circle and outer circle) under the same steel content are compared and fire resistance of concrete filled double steel tubular short columns are analyzed. The results show that increasing the thickness of the inner steel tubular when the diameter is constant and increasing the diameter of the inner steel tubular when the thickness is constant are conducive to the improvement of the fire resistance；Under the condition of keeping the overall steel content unchanged, the fire resistance limit of concrete-filled double steel tubular columns with different section combinations is almost the same, but on the whole, the fire resistance of concrete-filled double circular steel tubular short columns is better; In addition, the fire resistance of double concrete-filled steel tubular composite columns is much higher than that of ordinary concrete-filled steel tubular columns.