Experimental investigation of CHS T/Y‐joints fabricated from high‐strength steel

Abstract

In this study, an experimental program on welded hollow section joints fabricated from high‐strength steel is presented. The experimental program tested a total of six T or Y cold‐formed circular hollow section (CHS) joints under brace axial compression. One mild steel with a nominal yield stress of 355 MPa and two high‐strength steels with nominal yield stresses of 460 and 650 MPa were included. The test results and existing test database were used to evaluate the relevant design provisions for high‐strength steel joints. The material factor – used in the current standards to reduce the design resistance of high‐strength steel tubular joints – was found to be adequate for CHS T/Y‐joints with steel grades up to 700 MPa. The chord stress effect resulting from a particular test setup needs to be considered when evaluating the experimental joint strength. The experimental load‐indentation relationships were analysed to appraise the behaviour of high‐strength steel CHS T/Y‐joints from the perspectives of ductility and serviceability. The ductility of high‐strength steel T/Y‐joints is slightly lower than that of mild steel joints. T/Y‐joints show relatively lower ductility and serviceability performance compared to CHS X‐joint counterparts that comprise identical members. Local strain distributions in tested T/Y‐joints of different steel grades were analysed to identify the location and intensity of strain concentration. The possibility of fracture failure near the weld seam of the cold‐formed chord member is discussed.

Static Behaviour of High‐Strength Steel CHS T‐Joints under In‐Plane Moment Loading

“…The Riks algorithm was employed to capture any possible instability. For more details regarding the modelling scheme, readers may refer to [25]. Rigid cap plates were modelled at the ends of chord and brace.…”

“…Chord diameter and length were fixed to 400 and 4,000 mm, respectively. A chord longer than ten times its diameter is known to have a saturated length [25]. Elastic steel with E = 200,000 MPa was applied to the brace, to prevent any brace failure.…”