Fire and post-fire performance of blind-bolted concrete-filled steel tubular joints with restrained steel beams: Experiment and simulation

Abstract

Blind-bolted connection is a type of new developed prefabricated beam-column connection, which can be used to connect the concrete filled steel tubular (CFST) columns and the steel beams easily. The static and dynamic performance of CFST column to steel beam joints with blind-bolted connections have been well explored, but limited research has been conducted to investigate the fire and post-fire performance of this type of composite joint. In this paper, a series of reversed T-shaped joint fire tests were conducted to investigate the fire and post-fire performance of blind-bolted CFST joints with axially restrained steel beams. The influence of restrained effect from adjacent members in the entire frame structure on the response of blind-bolted joints in and after fire could be reasonably considered by the reversed T-shaped joint fire test. The joint temperature, failure modes, beam and column displacements and temperature internal force development during the entire loading and fire stage were recorded and discussed. The test results indicated that the blind-bolted connections showed very good working performance in and after fire, and no bolt shank fracture or bolt pull-out failure was observed. Finite element analysis (FEA) models were established to simulate the fire and post-fire performance of blind-bolted CFST T-shaped joints with axially restrained steel beams, and the joint moment versus relative rotation angle relationship curves of the blind-bolted joints during the entire fire and loading process were extracted and discussed based on the FEA models. The results indicated that the joint negative moment generated by the axially restrained beam boundary in the heating and cooling phases could go up to around 1.4 times the joint negative moment at ambient temperature.