Testing of semi-rigid steel–concrete composite frames subjected to vertical loads

A pair of tests carried out on full-scale semi-rigid composite frames with two stories and two bays are reported. The composite frames undergoing tests are composed of steel columns and steel–concrete composite beams. The beam-to-column connection consists of a flush end plate welded to the beam end and bolted to the column flange. To investigate the influences of semi-rigid connections and composite action of the slab on the performance of the steel frames, the overall response of the frame specimen, the connection behavior, and the beam’s behavior when subjected to vertical loads have been measured and analyzed. The nonsymmetrical loading effect is also considered. It is found that the composite endplate connection, which is semi-rigid and of partial strength, has reasonable strength and stiffness, and its rotation capacity satisfies the ductility requirement of no less than 30 mrad for earthquake-resistance. The effects of the flexibility of the connections and the composite action of the slab on the strength, stiffness, and ductility of steel frames must be properly considered in the design.