Experimental evaluation of plate-reinforced steel moment-resisting connections

Five cover-plate and five flange-plate single-sided steel moment-resisting beam-column assemblies were tested at full scale. Grade 50 steel was used for the W14 × 176 columns, the W30 × 99 beams, and all reinforcing plates. The procedures of FEMA 267A were used to design and detail the connections that included rectangular-, trapezoidal-, and swallowtail-shaped reinforcing plates. Cyclic and near-field loading histories were used to test the connections. None of the ten connections failed in a brittle manner; the strength of each connection degraded slowly due to local buckling of the beam web and flanges. The maximum beam plastic hinge rotations ranged between 2.3 and 3.9% rad. The cover-plate and flange-plate connections performed equally well but neither connection was subjected to large plastic strains at the face of the column. The performance of the tested plate-reinforced connections was best when rectangular reinforcing plates and three-sided fillet welds joining the reinforcing plate to the beam flange were used. Bracing of the beam bottom flange outside the plastic hinge zone to delay lateral-torsional buckling did not produce any significant improvement in connection hysteresis. Increased beam web compactness (smaller height to thickness) delayed the loss of strength and stiffness in the beam-column connection.