弯矩分布模式对约束PEC柱抗火性能的影响

在实际火灾中,结构中的柱子可能受到轴力和不同分布模式弯矩的共同作用。弯矩分布模式的不同将导致柱的抗火性能产生一定差异。考虑结构中柱的实际受力状态,建立了ISO-834标准升温条件下四面受火约束PEC柱有限元模型,分析了不同轴向约束刚度比、荷载比和偏心率等参数情况下弯矩分布模式对约束PEC柱抗火性能的影响。结果表明,荷载比和偏心率较小时,不同的弯矩分布模式对PEC柱的变形特征和轴力变化系数影响不大;随着荷载比和偏心率的增大,对弯矩分布模式的影响变大。在其他参数相同的情况下,均匀弯矩分布模式下柱的耐火极限最短;三角形弯矩分布模式和异号弯矩分布模式下PEC柱耐火极限差别不大。

Influence of bending moment distribution mode on fire behavior of restrained PEC columns

In practical fire situation,columns in structures may be subjected to the combined action of the axial force and bending moment with different distribution modes.The difference of bending moment distribution modes may lead to a different fire behavior of PEC columns.Considering the actual state of structural columns,the paper developed the finite element model of restrained PEC column subjected to ISO-834 standard fire from 4-side,and analyzed the influence of different moment distribution mode on fire behavior of restrained PEC columns,in which parameters including axial restraint stiffness ratio,load ratio and eccentricity were considered.Results show that the moment distribution mode has little effect on the deformation and axial force variation coefficient in case of low load ratio and eccentricity ratio.With the increase of the load ratio and eccentricity ratio,the impact of moment distribution mode increases.When other parameters are same,the fire resistance is the shortest one under the uniform bending moment distribution mode.Fire resistance of PEC column has little difference under the triangular bending moment distribution mode and the reverse bending moment distribution mode.