约束高强度Q460钢柱抗火性能试验

Fire tests on restrained high strength Q460 steel columns

为获得高强度Q460钢柱的抗火性能,采用火灾试验炉对4个约束Q460钢柱进行抗火性能试验,试验采用恒载升温模式和ISO-834标准升温曲线,考虑了两个约束刚度和两个荷载比,测量了钢柱受火过程中的温度、轴向位移和跨中挠度,并得到了约束Q460钢柱的屈曲温度和破坏温度,采用约束钢柱的轴力放大系数方法计算了试件的破坏温度并和试验结果进行对比.研究表明:轴向约束刚度和荷载比对Q460钢柱的抗火性能影响较大,相同荷载比下轴向约束刚度大的钢柱破坏温度低,相同约束刚度下荷载比大的钢柱破坏温度低;轴力放大系数方法可以确定约束高强度Q460钢柱的临界温度.

Fire tests on four restrained columns fabricated with Q460 steel were carried out using furnace to obtain the fire resistance of high strength Q460 steel columns. The temperature of the furnace follows ISO-834 standard curve with the applied load keeping constant. Two restraint-stiffness ratios and two load ratios were considered, and the temperature distribution, axial displacement and deflection at the mid-section of steel columns were recorded in the tests. The buckling and failure temperatures of restrained Q460 steel columns were obtained. The failure temperature of specimens were calculated by employing the method of amplification factor of axial force in axially restrained steel columns and the results were compared with test results. The study shows that both the axial restraint and load ratio have great influence on fire resistance of Q460 steel columns. For certain load ratio, the failure temperature is lower for the steel column with the higher axial restraint, and for certain restraint stiffness, the failure temperature is lower with the higher load ratio. The method of amplification factor of axial force in axially restrained steel columns can be used to predict the critical temperature of restrained high strength Q460 steel columns.