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基于有限元方法模拟约束钢柱在火荷载作用下的抗火行为,分析轴向约束刚度、转动约束刚度、同向曲率的端弯矩作用对其抗火性能的影响,探讨轴向约束刚度、转动约束刚度与临界温度之间的关系。通过对约束钢柱火灾下的受力及变形性能较为全面地进行参数分析,得出:轴向约束刚度比增大,钢柱临界温度降低;转动约束刚度比增大,临界温度升高;在轴向约束条件下,截面温度分布均匀时端弯矩作用使钢柱临界温度显著降低;截面温差为200℃时,端弯矩作用的不利影响更加明显,端弯矩作用越大,受约束钢柱抗火性能越低;具有转动约束的钢柱,约束作用较小时,端弯矩作用会对其抗火性能产生不利影响,约束作用较大时,端弯矩作用对其抗火性能影响较小;截面温差为200℃时,端弯矩作用下的转动约束钢柱临界温度值几乎与轴向荷载作用下相同。另外,划分了“安全区”和“非安全区”两个区域,在抗火设计中保证钢柱的温度在安全区范围内,钢柱的抗火能力即可满足要求;端弯矩作用对约束钢柱抗火性能具有不利影响,会使安全区范围缩小。
Based on the finite element method (FEM) simulating the fire behavior of confined steel columns under fire load, the effects of axial restraint stiffness, rotational restraint stiffness and end bending moment of curvilinear curvature on its fire resistance were analyzed. The effects of axial restraint stiffness, Relationship Between Rotational Constraint Stiffness and Critical Temperature. Through more comprehensive parametric analysis of the stress and deformation under confined steel column fire, it is concluded that the axial restraint stiffness ratio increases, the critical temperature of steel column decreases, the rotational restraint stiffness ratio increases and the critical temperature increases. Under the axial restraint condition, the critical temperature of steel column decreases remarkably when the cross-section temperature distribution is uniform. The adverse effect of end-bending moment is more obvious when the temperature difference is 200 ℃, The lower the column fire resistance; steel column with rotation constraint, the smaller the restraint effect, the end bending moment effect will have an adverse effect on the fire resistance performance, the restraint effect is larger, the end bending moment effect on its fire resistance performance When the temperature difference of cross section is 200 ℃, the critical temperature of the steel column with rotation restraint under the action of end bending moment is almost the same with the axial load. In addition, the division of the “safe area” and “non-safe area” two areas, in the fire-resistant design to ensure that the temperature of the steel column within the safe area, steel fire resistance to meet the requirements; The bending moments have an adverse effect on the fire resistance of the confined steel columns and will narrow the safety zone.