Influence of geometrical imperfection of rib stiffeners on beam-to-column joint behaviour

The introduction of rib stiffeners in the extended end-plate joints can guarantee a beneficial increase of both the strength and ductility of the connection. Indeed, the presence of the rib influences the yield line distribution in the tensile zone of the connection, the depth of internal lever arm as well as the resistance of compression components of the joint . However, unexpected phenomena can develop if the stiffeners are not properly aligned with the beam web. Therefore, in this work, a parametric finite element (FE) analyses was conducted to investigate the influence of the rib constructional imperfection on both the local and global joint response. In particular, the variation of the compression center position and the development of additional internal actions in the bolt rows was monitored for five different rib misalignments. The results show that some geometrical imperfections could have a beneficial effect on the joint capacity limiting the beam out-of-plane mechanism when the plastic hinge develops at the beam extremity. © SDSS 2019 - International Colloquium on Stability and Ductility of Steel Structures.