Abstract: The fire resistance performance of square concrete filled steel tubular (CFST) column to steel beam frames is studied. Based on the finite element (FE) method, the FE model is established to analyze the temperature field, fire resistance time, and failure mode of the square CFST column to steel beam frame structure with reinforced concrete slab and blind bolted connections under the GB/T 9978 (identical with ISO-834) standard heating curve. The results of the finite element simulation are verified with experimental results. Based on experimental results, the difference of fire resistance between square CFST column members and square CFST frame columns is analyzed with FE method. The analysis results show that compared with other region of square CFST frame columns, the temperature in the joint region of square CFST frame columns is relatively lower. According to the frame structure judgment criterion proposed in this paper, when the blind bolt connection was reliable, the failure modes of square CFST column to steel beam frame reaching the fire resistance limit are mainly column failure mode and steel beam failure mode with the changing of load level acting on columns and beams. When no load is applied on the frame beam, it only restricts the frame column, and when other conditions are the same, the fire resistance limit of the square CFST frame column is greater than that of the hinged column member at both ends, but it is less than the fire resistance limit of one end fixed and one end hinged column member.

Key words: square concrete filled steel tubular column, H-shaped steel beam, reinforced concrete slab, blind bolt, fire resistance limit