EFFECT OF ZINC-RICH PAINT THICKNESS AND NUMBER OF CONTACT SURFACES ON BOLT PRETENSION LOSS IN HIGH STRENGTH BOLTED JOINTS

Abstract

 It is known that high strength bolted joints treated with zinc-rich paint have a characteristic of large bolt pretension loss by relaxation. Furthermore, it has been found that this type of joint causes a larger bolt pretension loss when the zinc-rich paint has a thick film thickness or when a filler plate is used. On the other hand, the effect of the mutual relationship between the film thickness and the number of contact surface on the bolt pretension loss is unknown. In this study, relaxation test and slip test of high strength bolted connection specimens were carried out with the film thickness of the zinc-rich paint and the presence of the filler plate as parameters. From these results, we discussed the initial bolt pretensions on high strength bolted joints treated with zinc-rich paint considering number of contact surface.