Fatigue Behaviour of Bolt-Welded Joints for U-Ribs in Orthotropic Steel Bridge Decks

Abstract:

Two full scale specimens of orthotropic steel decks with on-site bolt-welded U-rib connection detailing were designed and fabricated, and then the fatigue tests were conducted. A FE model of bolt-welded joints for the orthotropic steel bridge decks was proposed. The FE analysis showed that the longitudinal stresses in the inner connection plate were higher than those in the outer connection plate, and the stresses were influenced by the out of plane bending in the bolted U-rib joints. Stress distribution along the axial direction of the connection plate appeared a saddle-like shape. The stresses in the center region were higher than those in the end, which led to the fact that fatigue cracks appeared earlier in the center region of the inner connection plate in the both specimens. It is suggested that the fatigue strength of bolted U-ribs joint in the orthotropic steel decks be evaluated based on the fatigue design curve of category 71 in EUROCODE or the fatigue design curve of category IX in the Code for Design of Steel Railway Bridges. A parameter study base on FE analysis was further developed to optimize dimensions of the bolt connection plates and to improve the fatigue performance of the steel bridge decks.