High strength steel bolted connections with filler plates

The effects of undeveloped filler plates were experimentally evaluated for high strength steel bolted connections using standard size holes, oversize holes and multiple fillers. Filler plates up to 51 mm (2 in.) thick were utilized in connecting high performance A709 HPS 480W (HPS 70W) grade steel plates using 22 mm (0.88 in.) A490 bolts. With increasing filler thickness, the connection strength was found to decrease up to a limit and then recover for thicker fillers in standard and oversized hole connections. Multiple filler connections experienced the greatest strength decrease as the bolt failure shifted to the threads located outside the shear planes. Deformations also exhibited a limit, however the use of oversize holes resulted in 1.7 times larger deformations than standard or multiple fillers. Recommendations were developed for strength reduction and deformation amplification as function of filler thickness and bolt diameter.