Study of Fatigue Performance of Butt Weld Joints for Longitudinal Ribs of Orthotropic Steel Bridge Deck

To study the fatigue sensitivity areas of the butt weld joints for the longitudinal ribs of orthotropic steel bridge deck and determine the relevant reasonable structural parameters, 2 deck model specimens with the butt weld joints for the longitudinal ribs were designed, fabricated and the fatigue tests were made. The finite element model for the deck was established, using the software ANSYS and the longitudinal stresses in the sections of the weld joints were calculated. The submodel for a butt weld joint was established as well and the influences of the weld joint width and shapes and the longitudinal rib thickness on the longitudinal stresses in the sections of the weld joints were analyzed. The results reveal that the fatigue cracks of the 2 specimens all initially start in the outer round-arc transition areas of the weld joints for the longitudinal ribs and then extend towards the bottom and webs of the ribs. The longitudinal stresses in the sections of the weld joints are great at the bottom horizontal sections and in the round-arc transition areas, the stress concentration exists in the outer round-arc transition areas and the areas are deemed to be the fatigue sensitivity areas. The decrease of the weld joint width, optimization of the weld joint shapes and increase of the longitudinal rib thickness can reduce the longitudinal stresses in the sections of the weld joints and improve their fatigue performance, of which the effect of the increase of the longitudinal rib thickness is most significant. © 2018, Journal Press, China Railway Bridge Science Research Institute, Ltd. All right reserved.