ANALYSIS ON FIRE PERFORMANCE OF CONCRETE-FILLED STEEL TUBULAR (CFST) TRIMPLE-LIMB LACED COLUMNS

A finite element analysis (FEA) model is established to study the fire performance of concrete-filled steel tubular (CFST) triple-limb laced columns subjected to ISO834 standard fire including heating and cooling phases. Some key issues regarding the fire performance of CFST triple-limb laced columns, including the failure mode, the axial deformation and load distribution on each CFST chord are studied when the columns reach a limit state, based on the FEA model. Besides, the influence of the load ratio and heating time ratio on whether the CFST triple-limb laced columns would reach a limit state in the cooling phase of fire is discussed. It can be found that the column could reach a limit state both in a heating phase and a cooling phase of fire. With the increase of a heating time ratio at an identical load ratio, or with the increase of a load ratio at an identical heating time ratio, the possibility of the column reaching the limit state in a cooling phase increased, and the failure time in the cooling phase decreased.