Inelastic response of composite base column connections

This paper assesses the experimental results of monotonic (pushover) tests carried out on partially encased composite steel-concrete columns connected to the foundation block through the traditional layout comprising bolted steel end plate and an innovative socket type system. The results of the experimental tests demonstrate that the structural response of the traditional connection is significantly influenced by the behaviour of the anchorage bolts. The latter cause large fixed end rotations and possess limited energy dissipation. Conversely, innovative composite steel-concrete base column connections with socket systems exhibit enhanced overstrength, inelastic deformations and energy absorption capacity. Furthermore, socket-type connections are characterised by spreading of inelasticity at the base of the composite columns without damage localization on concrete and interface components.