Seismic design and testing of EC8-1-2-compliant unstiffened end-plate beam-to-column joints

Cyclic tests and finite element simulations were carried out to investigate the performance of partial strength unstiffened end-plate joints that have been designed either for moment frames in low seismic areas or to provide redundancy, ductility, and extra dissipation capacity of dual frames (i.e., braced frames as primary seismic resisting system in combination with moment frames as secondary system) in the framework of the second generation of Eurocode 8. The tested joints have been designed to promote yielding in the end-plate connection and the column web panel in shear, while preventing the failure of the bolts and welds in the range of the required plastic rotation for highly ductile structures. Three beam-to-column assemblies have been considered to account for the influence of the size of members. Moreover, the tested specimens were designed to vary the relative resistances of the column web panel and connection as follows: (i) balanced column web panel and equal strength connection, (ii) balanced column web panel and partial strength connection, (iii) weak column web panel and equal strength connection, (iv) weak column web panel and partial strength connection. The adopted design criteria of the tested joints are described, and the main technological details are also reported. The tested joints were also numerically investigated using finite element simulations. The accuracy of advanced numerical models was verified against the performed experimental tests, and the validated models were used to investigate the local response of the joints, thus highlighting the influence of both geometrical and mechanical parameters.