Bolted steel slip-critical connections with fillers: II. Behavior

Research has been conducted to better understand the effect of fillers in bolted steel connections. In a companion paper, the results of sixteen experiments on bolted steel slip-critical connections with fillers are presented along with proposed design recommendations. In this paper, detailed behavior of the specimens is documented through an examination of deformation and strain response. Additionally, mechanisms are proposed that clarify key aspects of the behavior of bolted connections with fillers, including prediction of slip and shear strengths. A stochastic analysis, using order statistics, is employed to quantify the detrimental effects of multiple possible slip surfaces on expected slip strength. The use of multiple plies and the effects of developing the filler plate are investigated with respect both to the experimental results and the proposed behavioral mechanisms. The results indicate that the use of multiple plies exacerbates the detrimental effects on slip strength and, to a lesser extent, on shear strength. Furthermore, filler development reduces and in many cases eliminates the reduction in slip and shear strengths.

Research highlights
► Developing filler plates helps negate the effects of multiple fillers in bolted steel connections.
► Extending bolted steel connections with fillers helps negate the effects of multiple fillers.
► Bolt shear strength reduces as a function of the thickness of the filler in bolted steel connections.
► With thick fillers, jammed bolts reduce reductions in bolt shear strength due to fillers.