Bearing strength at bolt holes in connections with large end distance and bolt pitch

Abstract

The paper presents test results of one and two bolt connections with very large end distances that failed in bolt bearing, where very high bearing forces were recorded. The purpose of the tests was to investigate the behaviour of the plate in bearing that was not limited by shear, splitting, bolt or net cross-section failure, but with tearing of the material in front of the bolt. The tests showed that the bearing capacity increased insignificantly as the width of the plate increased. Numerical simulations show that bearing resistance is in cases of large end distances significantly influenced by friction forces. They develop because the bolt head and nut, together with the lap plates, constrain the increase of the plate thickness related to plastic deformation. The paper deals with the formation of the stress-strain field as well as the influence of the inner bolt determined by the numerical simulations. The resistances obtained from the tests agree very well with the bearing strength model presented recently by Može and Beg (2014). The coefficient of the bearing strength model that considers the influence of the inner bolt is calibrated on the basis of the presented test results as well as on high strength steel connections with several bolts. The presented bearing strength model was adopted in the final draft of the second generation of EN 1993-1-8.