内嵌十字型钢的方形劲性不锈钢管混凝土柱耐火性能

Fire Resistance of Square Steel Reinforced Concrete-filled Stainless Steel Tube Columns Embedded with Cross-section Steel

通过在不锈钢管混凝土柱中内嵌型钢组成劲性不锈钢管混凝土柱,在降低不锈钢用量的同时使柱体具有更优的延性和耐火性能。采用有限元模拟的方法对内嵌十字型钢的方形劲性不锈钢管混凝土柱的耐火性能开展研究。首先建立火灾下方形劲性不锈钢管混凝土柱耐火性能分析的有限元模型,并采用相关试验的温度场及耐火性能数据对其进行充分验证;基于验证的有限元模型,对不同荷载比作用下一典型劲性不锈钢管混凝土柱的温度历史、轴向位移-时间关系、典型破坏模态和截面内力重分布等开展分析,明确其火灾下的工作机理;同时与等含钢率的不锈钢管混凝土柱开展对比分析。结果表明:内嵌型钢有助于提高高温下柱体的轴向、侧向刚度,劲性不锈钢管混凝土柱的破坏模态表现为轴向压缩破坏;在低火灾荷载比下,由于型钢分担部分从不锈钢转移的荷载,允许不锈钢发生更高的温度材性劣化,进而提高了柱体的耐火性能,火灾荷载比越小,该提升效果越显著。

The steel reinforced concrete-filled stainless steel tube column was composed by embedding profile steel in the concrete-filled stainless steel tube column,which reduced the amount of stainless steel and made the column have better ductility and fire resistance.The fire resistance of square steel reinforced concrete-filled stainless steel tube column embedded with profile steel was studied by finite element simulation.Firstly,the finite element model of fire resistance performance of square steel reinforced concrete-filled stainless steel tube column under fire was established,and the temperature field and fire resistance data of relevant tests were used to fully verify the model.Based on the validated finite element model,the temperature history,axial deformation-time relationship,typical failure modes and section internal force redistribution of a typical steel reinforced concrete-filled stainless steel tube column under different load ratios were analyzed,and the working mechanism under fire was defined.At the same time,the comparative analysis with concrete-filled stainless steel tube columns with equal steel content was carried out.The results show that the embedded profile steel is helpful to improve the axial stiffness and lateral stiffness of columns at high temperature.The failure modes of steel reinforced concrete-filled stainless steel tubular columns are manifested as axial compression failure.Under low fire load ratio,because partial profile steel shares the load transferred from stainless steel,it allows stainless steel to deteriorate at higher temperatures,thereby improving its fire resistance.The lower the fire load ratio,the more remarkable the improvement effect is.