Study on after-slip strength of high-strength bolted frictional joints with a filler plate

According to the new Japanese Specifications for Highway Bridges, after-slip behavior should be verified in high-strength bolted frictional joints. Previous studies have investigated slip behavior with a filler plate. They have proposed the reduction factor of slip resistance. On the other hand, the ultimate strength of such a joint with a filler plate is not clear, and its design strength considering after-slip behavior is not also specified. In this study, for high-strength bolted frictional joints with various filler plate thicknesses, tensile tests and FEA were carried out. From obtained results, it was revealed that a filler plate did not resist load in bearing, and the number of bolt shear failure surfaces was decreased to one from two by a filler plate. It is also found that bolt shear strength decreased below the designed value as filler plate thickness is increased. The authors also proposed the simple design model for bolt shear strength in the frictional joints with a filler plate.