Static resistances of cold-formed high strength steel tubular non-90° X-Joints. (15th July 2021)

• Record Type: Journal Article
• Authors: Pandey, Madhup; Young, Ben
• Is Part Of: Engineering structures. Volume 239(2021)
• Publication Date: 2021-07-15
• Subjects: Experimental investigation -- Non-90° X-joints -- Rectangular hollow section joints -- S900 and S960 steels -- Thin-walled structures -- Tubular connections; Structural engineering -- Periodicals; Structural analysis (Engineering) -- Periodicals; Construction, Technique de la -- Périodiques; Génie parasismique -- Périodiques; Pression du vent -- Périodiques; Earthquake engineering; Structural engineering; Wind-pressure; Periodicals; 624.105
• DOI: 10.1016/j.engstruct.2021.112064
• Languages: English
• ISSNs: 0141-0296

Abstract

Highlights: 26 cold-formed S900 and S960 steel grades non-90° X-joints were tested. Material properties from transverse compression and weld heat affected regions were also investigated. Chord face, chord side wall and combination of these two failure modes were observed. Static resistances were compared with the predictions of CIDECT and EC3. Existing design rules of CIDECT and EC3 are generally not accurate and reliable. Abstract: This paper presents a test programme to investigate the static joint resistances and load vs deformation behaviour of cold-formed high strength steel (CFHSS) tubular non-90° X-joints. The investigation presented in this study predominantly focused on the chord failure of non-90° X-joints under brace axial compression loads. The experimental programme comprised of 26 tubular non-90° X-joints, which were fabricated with three included angles ( θ1 ), i.e. 30°, 50° and 70°. Circular and square hollow sections were used as braces, while chords were made up of rectangular and square hollow sections. The nominal yield strengths of the tubular members were 900 and 960 MPa. The brace and chord members were connected using automatic gas metal arc welding process. The measured value of brace-to-chord width ratio ( β ) ranged from 0.53 to 1, brace-to-chord thickness ratio ( τ ) ranged from 0.52 to 1.01, chord width-to-thickness ratio (2 γ ) ranged from 20.5 to 38.7 and chord side wall slenderness ratio ( h0 / t0 ) ranged from 15.4 to 38.9. A total of three failure modes was observed, including chord face failure, chord side wall failure and combination of these two failure modes. The static joint resistances obtained from the tests were compared with the nominal joint resistances of X-joints given in the CIDECT and Eurocode 3. It is shown that the existing design rules in these specifications are not suitable for the design of S900 and S960 steel grades tubular non-90° X-joints. Further, the impact of the included angle ( θ1 ) on the joint resistances of X-joints was observed by comparing the joint failure resistances of tubular non-90° X-joints obtained in this investigation with the joint failure resistances of tubular 90° X-joints of identical nominal tubular member dimensions and steel grades. In addition, tensile material properties from the weld heat affected regions of S960 steel grade tubular members of different thicknesses were also investigated.