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在火灾条件下,约束钢柱轴力由于升温而增加,会导致在较低的温度下发生屈曲;但屈曲后,钢柱的轴向温度膨胀得到释放,轴力下降,因此屈曲后钢柱仍能继续承栽。本文通过计算长度系数将转动约束钢柱转换为铰支钢柱,给出了一种轴向约束钢柱在火灾升温条件下的临界温度的简化计算方法——轴力放大系数设计方法。此法通过轴力放大系数将轴向约束钢柱转化为无约束钢柱,再按无约束钢柱计算得到钢柱的临界温度。用验证过的有限元模型对简化计算方法进行了验证,计算结果表明简化方法吻合较好。
Under fire conditions, the axial force of the constraining steel column increases due to the temperature rise, which will lead to buckling at a lower temperature. However, after buckling, the axial temperature expansion of the steel column is released and the axial force decreases. Therefore, Can continue bearing. In this paper, a new method of calculating the critical temperature of axially restrained steel columns under the condition of fire temperature increase is presented, which is to calculate the axial force amplification factor by calculating the length coefficient and transforming the rotating constrained steel columns into the hinged steel columns. In this method, the axially constrained steel columns are converted into unconstrained steel columns by the axial force amplification coefficient, and the critical temperature of the steel columns is calculated according to the unconstrained steel columns. The simplified calculation method is verified with the verified finite element model. The calculation results show that the simplified method is in good agreement.