高强中空夹层钢管混凝土柱的耐火性能试验研究

EXPERIMENTAL STUDY ON FIRE BEHAVIOR OF HIGH STRENGTH DOUBLE-SKIN CONCRETE-FILLED STEEL TUBULAR COLUMNS

针对应用高强钢与超高强混凝土的中空夹层钢管混凝土柱,开展了轴心受压柱的标准耐火试验,得到了不同截面形状、边界条件、涂料厚度、荷载比条件下该柱的耐火极限,提出了表征柱耐火性能的延性指标,探讨了高强柱与普通柱耐火性能的差异。试验结果表明:高强中空夹层钢管混凝土柱的受火时间-位移响应与普通柱相似,受火前期膨胀而后期压缩变形进一步增大达到耐火极限。参数分析表明:相同条件下,应用高强钢的中空夹层柱其耐火极限低于应用普通钢的中空夹层柱,而应用超高强混凝土的中空夹层柱其耐火极限则高于应用普通或高强混凝土的中空夹层柱。此外,该文分别基于欧洲规范4中轴心受压柱和压弯构件的常温承载力计算模型,运用材料高温力学参数,计算了该柱高温屈曲承载力与耐火极限,计算结果与试验结果吻合较好。

Standard fire tests on double-skin concrete-filled steel tubular(CFST)columns using high strength steel(HSS)and ultra-high strength concrete(UHSC)were conducted.The effects of section shape,boundary condition,thickness of fire protection,load ratio on the fire performance were investigated,ductility index was proposed and the differences between normal-and high strength double-skin CFST columns were discussed.Test results show that the time-displacement response of such high strength columns is very similar to their counterparts with normal strength materials.The parametric analysis indicates that,with the other conditions remaining the same,the fire resistance time of columns using HSS is shorter than their counterparts with normal strength steel(NSS),whereas the fire resistance time of such columns with UHSC is longer than those with normal-or high strength concrete(NSC or HSC).Besides,the high temperature-dependent buckling resistance and fire resistance time were calculated based on the ambient temperature calculation modes of axially and eccentrically loaded columns in Eurocode 4 and using the temperature-dependent material properties of UHSC and HSS,and the predicted results agree reasonably with the test values.