Full-Scale Test of Composite Frame under Large Cyclic Loading

This paper presents an experimental study on a steel moment frame with reinforced concrete (RC) floor slab that was subjected to horizontal cyclic loading leading to very large deformations. The primary objective of this test was to examine the interaction (composite action) between the steel beam and the RC floor slab. The steel beam moment capacity increased about 1.5 times in positive bending with the presence of the RC floor slab. During small beam rotations of 0.002–0.003 rad, the beam strength increased 1.2–1.4 times in negative loading, but composite action did not affect the negative beam moment capacity for larger rotations. The effective width estimated from the slab compressive force approximately equals the column width. Fracture at the bottom flange was notable due to the presence of the slab in the composite beam. Complete separation of the beam-to-column connections was not achieved even at a beam rotation of 0.13 rad, under which the composite connections still possessed bending resistance equal to about 10% of the maximum bending capacity when sustaining positive bending.