Numerical Simulation of the Fire Response of a Frame with Concrete-Filled Steel Tube Columns

This paper studies the fire response of a frame with Concrete-Filled Steel Tube Columns (ST-RC column-RC beam). The structure was modeled in the finite element analysis platform ABAQUS, and the its validity was verified against experimental data. The model was subjected to fire and vertical load and the failure mode, deformation, internal forces, stresses, and fire resistance, and the factors that influence the fire resistance were analyzed. Two failure modes were detected: in the one, the beam of the frame is involved, and in the other, beam and column simultaneously fail. Under the combined action of fire and load, the bending moment of the beam and column changes significantly. The parameters that have a great influence on the fire resistance of the structure are the column and beam load ratios, beam to column linear stiffness ratio, column slenderness ratio, column section size, core area ratio of column section, and compressive strength of concrete around column. Considering the above main factors, a simplified calculation formula for the fire resistance of this frame is provided. This research can provide reference for the design of this kind of frame structure in practical engineering.