Experimental study of steel-timber composite (STC) beam to steel column joints having a flush end-plate

Abstract

In recent published works, the feasibility and composite action of steel-timber composite (STC) systems have been demonstrated through push-out tests on STC joints and bending tests on STC beams subjected to sagging (positive) bending moment. However, the behaviour of STC beams subjected to negative bending moments, where the comparatively high tensile strength of the timber slab (compared to a concrete slab) can significantly increase the bending moment capacity and stiffness of STC beam-to-column joints, remains unexplored. Accordingly, this paper investigates the negative bending moment capacity, stiffness and the rotational capacity of STC beam-to-column joints with flush end-plates. Six full-scale STC beam-to-column cruciform joints were fabricated and subjected to monotonically increasing static loading up to failure. The cross-laminated timber (CLT) slab width, the connection type between the CLT panels across the column (either steel plate or gluing) and degree of composite action between the CLT-slab and the steel beam were the main variables considered in the experimental program. It is shown that the composite action between the CLT-slabs and steel beam has a minor influence on the negative bending capacity and initial stiffness of the beam-to-column connection, but the type of CLT slab-to-CLT slab connection (spline with steel plate and/or glued butt joint) has a major influence on the structural behaviour of the STC beam-to-column connections.