Fire performance of blind bolted composite beam to column joints

Blind bolts can be used to connect steel beams to concrete filled steel tubular (CFST) columns, and the obtained composite joints have relatively high initial stiffness, flexural resistance, and ductility at ambient temperature. However, very limited research has been conducted on the fire performance of the blind bolted composite joints. In this paper, eight full-scale blind bolted joints were tested to study their fire performance. The test parameters include: (a) whether fire protection is applied to the steel beam or not; (b) beam load ratio (0.25 and 0.5); (c) type of steel used for the column (stainless or carbon steel); and (d) with or without binding bars in the connection region. The test results indicated that the joint failure was mainly dominated by flexural failure of the steel beam near the panel zone. In general, the blind bolted joints demonstrated very good performance in fire, and no bolt shank fracture or bolt pull-out failure was observed in any joint test. The beam protection or reduction of the beam load significantly increased the fire resistance of the joint, whereas the presence of the binding bars or the type of the steel tube had only moderate influence on the fire resistance.