Stress Characteristics and Fatigue Crack Behaviour of the Longitudinal Rib-To-Cross Beam Joints in an Orthotropic Steel Deck

Abstract

The welded joints between longitudinal rib and crossbeam of an orthotropic steel bridge deck are potentially critical to fatigue failure due to stress concentration at the end of the weld toe, caused by in-plane and out-of-plane deformations due to negative bending moments produced by live loads on the deck. The objective of this study is to evaluate the stress characteristics and fatigue crack behaviour of the longitudinal rib-to-crossbeam joints in an orthotropic steel bridge deck and to investigate the effectiveness of crack repair using a stop-hole. Static and fatigue test on full scale specimens were performed to observe the fatigue strength and crack propagation at the longitudinal rib-to-crossbeam joints. The measured stress distributions were compared with the F.E. analysis results. The test results show that fatigue cracks are initiated at the weld toe of the longitudinal rib-to-crossbeam joint with an inclined angle and rib-to-deckplate joint. Fatigue crack growth of the joint was analyzed by the mixed-mode analysis using the strain energy density factor. The stop-hole method was applied to delay fatigue crack growth of the longitudinal rib-to-crossbeam joint.