Root cracking in tubular joints with enhanced partial joint penetration welds

Abstract

This paper presents the experimental and numerical investigation on the fatigue cracking at the root of the enhanced partial joint penetration (PJP+) welds in the circular hollow section X-joint specimens subjected to constant-amplitude brace in-plane bending actions. The PJP+ welds, which include a portion of the brace wall as the inherent & quot;back-plate & quot;, reduce the workmanship requirement on the welding procedure and improve the quality control of the welded joint. This study compares the fatigue crack developments observed at both the weld toe and the weld root in two large-scale X-joint specimens with different post-weld surface treatments. Root cracking is hardly observed in as-welded tubular X-joint specimens without post-weld surface treatment, in which the fatigue life depends on the toe failure. In specimens with post-weld grinding treatments to enhance fatigue resistance of the material near the weld toe, however, the finite-length root face triggers the initiation and propagation of fatigue cracks, but with an applied number of cycles more than that required to initiate a toe crack in the identical as-welded tubular X-joint. © 2012 Taylor & Francis Group, London.