Robustness of seismically pre-qualified extended stiffened beam-to-column joints

Steel joints for moment resisting frames in seismic areas are designed in accordance with the capacity-based design principles This design philosophy can be also effectively implemented to enhance the robustness of structures against progressive collapse. In this article the effectiveness of seismic design criteria on the robustness of beam-to-column joints is investigated. The numerical investigation was carried out on a set of European beam-to-column assemblies equipped with extended stiffened end-plate connections. The beams in the analyzed models were axially-restrained and subjected to large rotational demands, characteristic of the column loss scenario. The results show that the joints designed in accordance with seismic requirements have an adequate performance, provided that the axial resistance of half of the connection is larger than the plastic resistance of the beam.