Performance of composite connections: Major axis end plate joints

Abstract The results of a series of five tests on composite beam-to-column connections are reported. The steelwork part of the connection used an end plate, welded to the beam and bolted to the column flange. For comparison, a sixth test was on a bare steel connection of the same type. Increasing the amount of reinforcement caused a rise not only in moment resistance but also in the rotation capacity of the composite connection. A similar result was obtained by replacing a flush end plate by an extended one. Increase in the depth of the steel section decreased rotation capacity. Plastic analysis of the composite connections, with forces in tension bolts predicted by Annex J of Eurocode 3, provides satisfactory prediction of moment resistance. Good rotation capacity in hogging bending is associated with a plastic neutral axis for the composite beam being in the top flange of the steel section. Large deformation of the lower part of this section by local buckling is the preferable failure mode, because no sudden drop in resistance occurs. A simple spring model can be used to predict satisfactorily a bilinear approximation of the moment-rotation curve, provided account is taken of the deformation of the shear connection.