The aim of this thesis was to investigate the effect of clearance and tolerance in bolted joints when there is a mismatch between the bolt holes. A parametric study with seven different cases was analyzed in this project; four double bolt configuration and three triple bolt configuration, with variation of the size of the bolt hole misalignment, the diameter of the bolt and the thickness of the plates. All analyses were performed with the aid of the FEM commercial software Abaqus, all the models were modelled with 3D brick elements. Despite bolted connections being subject of several investigations, no study about this matter for structural engineering purposes had been performed before. The results indicate that for connections with a low number of bolts a misalignment of the bolt clearance can cause a serious reduction in the ultimate bearing capacity of a joint and it indicates that the Eurocode 1993 1-8 might be overestimating the ultimate bearing capacity for some cases.