Experimental investigation on cold-formed high strength steel tubular T-joints after fire exposures

An experimental study has been presented to investigate the static strengths of cold-formed S960 steel T-joints after ISO-834 fire exposures. A total of 9 T-joints was tested after cooling down from 300 degrees C, 550 degrees C and 750 degrees C temperatures. Braces and chords were made of square and rectangular hollow sections. Automatic gas metal arc welding process was used to weld brace and chord members. The measured value of brace-to-chord width ratio (beta) ranged from 0.41 to 1.0, brace-to-chord thickness ratio (tau) rangedfrom0.98to1.02anchord width-to-thickness ratio (2 gamma) ranged from 30.6 to 35.3. The post-fire residual joint strengths were compared with the nominal strengths predicted from Eurocode 3 and CIDECT using the measured post-fire residual mechanical properties. It is shown that the existing design rules given in Eurocode 3 and CIDECT could not accurately predict the post-fire residual joint strengths of cold-formed steel tubular T-joints made of S960 steel grade.