Compression capacities of cold-formed high strength steel tubular T-joints

Abstract

The paper presents a test programme on cold-formed high strength steel tubular T-joints with fully supported chord members. The T-joints consist of brace members made up of square, rectangular and circular hollow sections, while chord members were made up of square and rectangular hollow sections. The T-joints were fabricated by both brace and chord members made up of square and rectangular hollow sections as well as circular hollow section braces were welded to square and rectangular hollow section chord members. The brace and chord members were welded by semi-automatic gas metal arc welding process. The steel grade of 900 MPa was used for the square, rectangular and circular tubular members, while the steel grade of 960 MPa was used for the square and rectangular tubular members only. A total of 22 tests was conducted where an axial compression was applied through the brace members, while the chord members were resting on a solid flat base. The ratio of brace-to-chord width (β) ranged from 0.33 to 1, brace-to-chord thickness (τ) from 0.53 to 1.27, chord width-to-thickness (2γ) from 20.6 to 38.7, and chord side wall slenderness (h0/t0) from 12.7 to 38.6. The test results were compared with the nominal strengths obtained from the Eurocode 3 (EC3) and CIDECT for the assessment of the existing design rules for tubular T-joints with fully supported chord members. It is found that the existing design rules are not applicable for the design of cold-formed high strength steel tubular T-joints with fully supported chord members.