Fatigue strength of longitudinal load-carrying welds in beams made of ultra-high-strength steel

Abstract

The present study experimentally investigates the fatigue strength of longitudinally loaded welded joints in beam structures made of ultra-high-strength steel. Hereby, the effects of different manufacturing methods and welding preparations on the fatigue strength and the crack initiation locations of welded box and I section beams are evaluated. Specifically, experimental fatigue tests are carried out on welded these beams prepared with manual and automatic welding, and subjected to a constant amplitude four-point bending with an applied stress ratio of R = 0.1. The results show a variation in fatigue strength, whereby high performance is achieved using both single- and double-sided welds, particularly if the longitudinally continuous weld penetration is controlled by sufficient support of the weld root face. Current fatigue design codes and guidelines are applicable, albeit with some conservatism, for assessing the fatigue strength of longitudinal load-carrying welded joints made of ultra-high-strength steel.