考虑火灾全过程的钢管混凝土组合框架力学性能初步研究

Preliminary Research on Mechanical Behavior of Composite Frame with Concrete-filled Steel Tubular Columns after Exposure to Overall Stage of Fire

为进一步研究真实火灾工况下钢管混凝土组合框架的抗火性能,基于有限元软件ABAQUS建立了单层单跨圆形钢管混凝土柱-组合梁平面框架经历火灾全过程的数值分析模型。通过合理选取热工参数,进行了组合框架在ISO-834标准升降温曲线下的热传分析,研究了组合框架钢管混凝土柱与组合梁截面温度场的变化规律;在热传模型的基础上,通过合理选取材料本构模型、单元类型、边界条件以及网格划分等,对经历常温加载、升温、降温以及火灾后的钢管混凝土柱-组合梁平面框架的力学性能进行初步探讨。结果表明,由于钢筋混凝土楼板在受火过程中的吸热与约束作用使组合框架在受火后仍具有较高承栽力。该方法可进一步完善钢管混凝土结构抗火分析理论,也可供实际工程应用参考。

In order to simulate the real fire resistance in the projects,this paper presented a finite element model（FEM） of concrete-filled steel tubular（CFST） columns and composite beam single-story-single-span planar frame after exposure to overall stage of fire based on ABAQUS.The whole phases including loading at ambient,heating,cooling and post-fire,which followed the ISO-834 standard fire curve.The temperature model was established with the determinations of thermal parameters of steel and core concrete.The temperature distribution of CFST columns and composite beam was calculated using FEM.The mechanical behavior of CFST columns and composite beam frame working in entire stage of fire was discussed in this paper.The result shows that：The CFST composite frame still has high bearing capacity after exposure to overall stage of fire due to the heat absorption and the constraint function of reinforced concrete floor.The results of this paper can provide a basis for fire-damage assessment of composite beam frame with CFST columns.