The Research Of The Fatigue Property Of Site-butt Of Orthotropic Steel Bridge Deck

The fatigue of orthotropic steel deck is a long-term problem which slow down rhe development of the the steel bridge to the strucutre engineer scence the orthotropic steel deck was wade-used in 1960s.Absolute majority of the butt joint of the U-rib was weld joint.As the recent research,the U-rib weld butt was the normal cracked structure because only overhead welding can be used in the site welding of the steel box-beam which means the quality of the wled line is low and there are plenty of defects and cracks in the weld line.Two methods include Nominal Stress Method and Hot Spot Stress Method were used in the research of the fatigue property of all-weld and bolt-weld-co-used joint of the U-rib.It was found that the fatigue strength of the bolt-welding-co-used joint is still much higher than all-weld joint though the cross section is weakened by the hand hole.The experiment piece was cutted apart after the fatigue experiment so the defects of the wled line should be showen.It was found that there are gaps between the U-rib and the gasket and which downgrade the fatigue strength of the joint.The huge amount of heat was pour into the gasket and which should respound for the wrap of gasket.The experiment of the bolt-weld-co-used joint showed when the plant which was as thick as the U-rib was used,all the crack was distributed on the splice plate.The splice plate cracked before U-rib means the repair of the fatigue crack on the beidge was simplified.At last,a FEM modle based on the real bridge had been built to verify the difference of all-weld joint and weld-bolt-co-used joint under the standard fatigue car method.