When attaching members with high strength bolts, the filler plate is processed to have projections and is sandwiched between the new members to ensure the coefficient of slip without removing the paint film of the existing structure that contains lead. Considering that the bolts are subject to relaxation due to the paint film, we considered retightening and increasing the primary tightening axial force. A slip test was carried out to verify the slip strength of the filler plate with projections.
