Resistance and strain during tearing for tubular joints under reversed axial actions: Fid-Bau Portal

Resistance and strain during tearing for tubular joints under reversed axial actions

Liu, Tianyao / Qian, Xudong / Wang, Wei / Chen, Yiyi

Abstract This article aims to predict the load versus crack growth ( $P - Δ a$ ) and strain versus crack extension ( $ε - Δ a$ ) relations in the ductile tearing process of welded joints made from circular hollow sections (CHS). The experimental program includes fracture tests on monotonically and cyclically loaded CHS joints, with a fatigue crack near the weld toe, under axial loadings applied in the brace. Coupled with the tearing assessment diagram, this study integrates fracture resistance curves measured directly from joints and that from a fracture specimen under monotonic and reversed loadings in the experimental procedure. The tearing assessment estimates the evolution of the load resistance and the nominal strain versus the crack extension, both showing satisfactory agreement with the experimental results. This study translates the ductile tearing process into the load resistance and strain levels, which provides an interface between the fracture-mechanics based assessments and the engineering analysis and monitoring.

Highlights • This study presents the P-Δa and ε-Δa curves for CHS X-joints under reversed axial loads. • Joints under fully reversed loading exhibit significantly reduced fracture resistances. • The derived P-Δa and ε-Δa curves agree with the experimental results. • J-R curves from material and joint specimens lead to similar P-Δa and ε-Δa relationships.