圆钢管混凝土短柱的火灾后剩余承载力研究

在提出火灾全过程各阶段中钢管和核心混凝土应力-应变关系模型的基础上,采用有限元软件ABAQUS中的热-应力耦合分析模块计算了ISO-834标准火灾全过程作用后圆钢管混凝土轴压短柱的荷载-变形关系曲线,计算结果和试验结果基本吻合.对火灾全过程中圆钢管混凝土轴压短柱的荷载-变形关系、钢管和核心混凝土的截面应力分布以及两者之间的相互作用进行了分析,探讨了升温时间、初始荷载、截面含钢率、钢材强度、混凝土强度、防火保护层厚度和截面尺寸等参数对圆钢管混凝土轴压短柱剩余承载力的影响规律,最终提出了圆钢管混凝土轴压短柱剩余承载力的简化计算公式.

Research on the Residual Strength of Concrete-filled Circular Steel Tube Stub Columns after Exposure to Fire

On the basis of the proposed stress-strain relationships of steel and concrete of concrete-filled circular steel tubes (CFCST) at each stage of fire exposure, fully coupled thermal-stress analysis model in finite element soft ABAQUS was developed to predict the load-deformation relationship curves of axially loaded CFCST stub columns after exposure to ISO-834 standard fire. The predicted results were in good agreement with test results. The finite element analysis model was then used to investigate the behavior of CFCST stub columns by examining the load-deformation relationship, the cross-sectional stress distributions of steel tube and concrete core and their interaction during the entire stage of fire exposure. Parametric analysis was conducted to investigate the influence of heating time, initial axial, steel ratio, steel yield strength, concrete cube strength, spray insulation thickness and sectional size on the residual strength of axially loaded CFCST stub columns. Finally, a set of formulas was proposed to predict the residual strength of axially loaded CFCST stub columns after exposure to fire.