Validation of Numerical and Analytical Model of Bearing Type Bolted Steel Lap Joint with Friction-Slip Mechanism and a Threaded Portion of the Shank in Bearing

he paper presents experimental investigations and numerical analysis of bearing type lap joint behaviour with one bolt and two shear planes joining thin-walled steel parts. The aim of the study is to describe the actual force-displacement F-Δ relationship for the tested joints and to represent it numerically by validated models with varying degrees of geometry detailing in the finite element analysis. Validation involves determining properties of plates, bolts and the entire shear joint based on individual experimental testing. The obtained shear characteristic include all main stages of F-Δ connection behaviour, as elastic phase, friction, slip and bearing. Although bearing joints are analysed, friction-slip mechanism resulting from tightening of the bolts is also examined. Analyses also take into account existence of threaded portion of the bolt shank in bearing. FEA model with bolt thread confirmed its validity in terms of predicting load-bearing capacity with an overestimation of 1% with respect to the experimental average. However, simplified cylindrical model of the bolt shank appeared to be more reliable in terms of initial bearing stiffness, where the value was 20% higher comparing to the empirical results. An analytical characteristic of the considered joint was also derived based on the component method, which required certain assumptions and adjustments to include the actual phases of connection behaviour. This approach provided a satisfactory match to the experimental results, characterised by underestimations of maximum force and initial bearing stiffness of 2.5 and 7.6% respectively.