Design of full-strength full-ductility extended end-plate beam-to-column joints

The analysis and modelling of the ultimate behaviour of beam-to-column connections is certainly one of the most studied topics in the field of steel structures. In particular, seismic design of steel frames is commonly carried out to assure the dissipation of the seismic input energy in so-called “dissipative zones”. The location of such zones depends on the connection ultimate behaviour. Therefore, connections have to be properly detailed in order to assure wide and stable hysteresis loops. Once avoided the yielding of columns, beam-to-column joints play a role of paramount importance. In fact, beam-to-column joints can be designed either as Full Strength (FS) or as Partial Strength (PS). In the first case, depending on the overstrength level, the input seismic energy should be dissipated by means of plastic cyclic excursions of the beam ends. In the second case, dissipation requires the plastic engagement of ductile joint components. This paper addresses the design criteria to be adopted to assure full-strength full-ductility behaviour of Unstiffened Extended End-Plate (U-EEP) beam-to-column joints. The validation of the design procedure is accomplished by three-dimensional finite element analyses with ABAQUS 6.13 software. Finally, in order to clarify the design procedure in detail, a worked numerical example concerning the design of an external joint is presented.