Effect of Number of Additional Bolts Outside Splice Plates on Behaviour of Frictional Type Bolted Joints with a Filler Plate

In recent steel bridges, for improving productivity and constructability, members which have different dimensions are connected by high-strength bolts or welding. As for bolted joints, it’s known that the difference in thickness of connected members is adjusted with loose type or tight type fillers. End of the former plate is aligned on end of splice plates, and the latter is connected to a member with additional bolts outside the joint. However, the difference of the mechanical behaviour between the joint with them isn’t clarified. In this study, tensile tests and FEA of high-strength frictional bolted joints with loose and tight filler plates were conducted to investigate the difference of their load transfer mechanism and mechanical performance. From obtained results, it’s found that load carrying capacity of joint such as slip coefficient, maximum load was decreased by presence of a filler plate and its connection method, and additional bolts outside splice plates can hardly contribute to the performance enhancement of the joint with a filler plate. So, loose type filler is more preferably used than tight type filler. The effect of additional bolts on the mechanical performance of joint is to equalize the load sharing ratio of splice plates. Therefore, in case that eccentric moment can’t be disregarded because thickness of a filler plate is large, tight type filler may prevent failure of the splice plate which is contacted with connected plate.