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

Abstract

This paper presents an experimental investigation on cold-formed high strength steel tubular T-joints. The fabricated joints included the braces and chords made up of circular hollow sections with nominal yield strength of 1100 MPa. A total of 12 T-joints was tested under axial compression through the braces without any preload in chords. The measured ratio of brace diameter to chord diameter (β) ranged from 0.65 to 1.02, while the measured ratio of brace thickness to chord thick­ness (τ) and that of chord diameter to chord thickness (2γ) varied from 0.66 to 1.01 and from 22.72 to 34.32, respectively. All the test specimens were failed in chord face failure (chord plastification). The test strengths and deformations of the tubular T-joints are presented in this paper. The test strengths were compared with the nominal strengths calculated from the design rules of Comité International pour le Développement et l´Etude de la Construction Tubulaire (CIDECT) and European Code EN 1993-1-8 (EC3-1.8). The applicability of these design guidelines for cold-formed high strength steel tubular T-joints with nominal yield strength of 1100 MPa was assessed. It is shown that the nominal strengths predicted by CIDECT and EC3-1.8 are unconservative for the cold-formed high strength steel T-joints under axial compression. Generally, it is found that the test strengths divided by chord yield strength and the square of chord thickness had a linear relationship with the values of the square of ratio of brace diameter to chord diameter (β2).