Experimental study and finite element analysis of seismic performance on enhanced joints in steel frame

In order to investigate the influence of different reinforcing plate forms on the seismic performance, tests and finite element analysis were carried out on four different enhanced joints including cover and flange transition plate reinforced joints, symmetric enhanced joint and rib enhanced joint. Bearing capacity, load-displacement hysteretic behavior, plastic deformation, energy dissipation capacity and failure modes of joints were analyzed in depth. The results show that under low cyclic loading, plastic hings of these four different enhanced joints are away from the beam-column connection weld location, and great plastic deformation appear at the beam flange and web near the plastic hinge with obvious energy dissipation. For these four different enhanced joints the relocation of plastic hinge design requirements is achieved and the weld brittle failure at beam-column joints do not occur. The form of the reinforcing plate has significant influence on bearing capacity, ductility and energy dissipation. The symmetric enhanced joint and rib enhanced joint have higher bearing capacity than cover and flange transition plate reinforced joints. Ductility and energy dissipation capacity of the latter two are greater than the first two joints. The influence of tectonic plates for seismic performance should be considered in design. On the whole, the flange-plate reinforced joint and the symmetric enhanced joint exhibit better seismic performance, which can be used in earthquake zone.