## 4 Results and Discussion
### Offset in Central Row  
In the third set of case studies, the bolts of the central row were arranged with a 20 mm offset to the lateral ends with respect to the outer ones as shown in Figure 12. This layout can be used for two purposes. The first purpose is to optimize the stress distribution between the joint components. Second, if the joint is to be left as visible, an offset can be introduced for aesthetical purposes. The horizontal spacing between bolt rows on the same side of the joint is kept constant at 60 mm. Concerning the variations considered, values of 40, 50, 60, 70, and 80 mm were assigned to the vertical distance between the non-central row and the horizontal symmetry axis. Second, the plate thickness values considered were, as in previous analyses, 3, 3.5, 4, and 5 mm.  
As shown in Figure 13, the equivalent plastic deformation decreased as the distance between the horizontal row bolts increased. Out of the twenty cases analyzed, only ten met the maximum equivalent plastic deformation of 5% of the EuroCode. For plate thicknesses equal to or greater than 3.5 mm, the effect of increasing plate thickness was negligible. With an offset in the central row, the distance between horizontal rows must exceed 60 mm to meet the maximum equivalent plastic deformation.  
Figure 12: Dimensions of steel plate and position of holes with offset in central row.  
Figure 13: Equivalent plastic maximum deformation for horizontal spacings of 50–60 mm with offset in central row.  
Figure 14 shows bolt shear utilization for the different distances between the horizontal bolt rows considered. For spacing between horizontal bolt rows equal to or smaller than 60 mm, the shear utilization decreased with increasing row spacing, virtually independent of plate thickness. If a spacing between rows greater than 70 mm was arranged, shear utilization rose, and the more thin the plate was. As a result, only seven of these joint designs met both EuroCode specifications. By separating the bolt rows by up to 80 mm, the stress distribution between the bolts in the joint is altered, causing the shear stress of the most peripheral ones to increase above their nominal strength when the plate thickness is equal or less than 4 mm.  
Figure 15 illustrates the von Mises stresses in the 3.5 mm thick plate with 60 mm vertical spacing between row bolts and the 5 mm thick plate with 80 mm vertical spacing between row bolts. The former represents the joint design with the thinnest plate that meets the EuroCode 3 specifications for the defined load stresses. The latter corresponds to the joint design that most satisfactorily meets the requirements. For both designs, we observed the zone with stresses of 275 MPa around bolts 21 and 23, with significant differences in the extension of the zones with high stresses.  
Finally, the results obtained in this last set analyzed were compared with those of the set in which the distribution of the bolts was aligned both horizontally and vertically.  
Figure 14: Bol shear utilization for horizontal spacings of 50–60 mm with offset in central row.  
Figure 15: von Mises stress distribution in plates: (**a**) 3.5 mm thick plate with 60 mm vertical spacing between row bolts; (**b**) 5 mm thick plate with 80 mm vertical spacing between row bolts. The numbering of bolts is indicated.  
It was observed that the latter designs rendered slightly better structural performances. When thinner plates are used, both the equivalent plastic maximum deformation and the shear utilization of the bolts increase significantly in the cases with an offset in the central row. Among the remainder of the plate thickness values, both the equivalent maximum plastic deformation and the shear utilization of the bolts increase slightly in the cases with an offset in the central row.