Fatigue performance of enhanced partial joint penetration welds for tubular joints

Abstract

This article presents the experimental and numerical investigation on the fatigue performance of a Circular Hollow Section (CHS) X-joint connected using a new set of weld details, namely the Partial Joint Penetration plus (PJP+) welds. The new weld details utilize a portion of the brace wall as the inherent "back-plate" for the welds. This reduces the workmanship requirement on the welding procedure and improves the quality control of the welded joint. The fabrication for the PJP+ welds consists of a two-stage profiling process for the brace end. The brace-to-chord intersection angle of 60° for the X-joint specimens represents a realistic joint configuration, which incorporates the PJP+ weld details corresponding to the most practical ranges of the local dihedral angle. The fatigue crack initiation occurs at the weld toe on the chord member, which shows a lower SCF value but a higher notch stress than the corresponding values on the brace member. The experimentally measured fatigue life exceeds the S-N fatigue life prediction using the AWS curve DT and API RP 2A curve X by 10 to 15 times. © 2010 The University of Hong Kong.