Experimental, numerical and analytical investigation of fire resistance of prefabricated angle steel lattice concrete composite column

The angle steel lattice concrete (ASLC) composite column incorporates core concrete, concrete cover and latticetype skeleton connected by angle steels and batten plates. The lattice-type skeleton is equivalent to the longitudinal and hoop reinforcement in ordinary concrete columns, simplifying connection and facilitating construction. Considering different thicknesses of concrete cover, fire tests without loading were conducted on four ASLC composite columns. Additionally, fire tests with loading were also performed on two full-scale ASLC composite columns. The experimental results also provided validation for the finite element model (FEM), and parametric analysis was carried out using ABAQUS, to reveal the impact of load ratio, thickness of concrete cover and eccentricity ratio on the fire behavior of the ASLC composite column. The results indicate that increasing the thickness of concrete cover leads to a linear decrease in steel temperature, significantly enhancing the fire resistance limit of ASLC composite columns. Accounting for the heat absorption properties of the concrete cover and core concrete, a temperature calculation method for angle steel based on the equivalent heat capacity method were proposed, as well as axial and eccentricity compression bearing capacity calculation method based on the reduced section method, which have high applicability for ASLC composite columns.