Analysis and testing of composite wood-concrete floor/deck systems

Experimental and analytical studies of composite wood-concrete floor/deck systems have been ongoing at Colorado State University. A novel shear key/anchor detail of overlaying solid wood floors in office buildings with a concrete layer, thus creating a composite floor, was adapted for this study. The detail utilizes a notch to transfer bearing stress and shear stress in the joined materials for interlayer force transfer, rather than connector shear. Compared to ordinary mechanical connectors, the connection detail develops a substantially higher degree of composite action. Systems are being studied for residences, offices etc. and short span bridges. Laboratory testing included pull-out tests on the anchors, interlayer slip tests on connection details, pilot load tests of full-scale beams and one-way floors and thick decks. This paper also describes the analytical study of the mechanics of the interlayer force transfer, surface to surface contact stresses at the notched-anchor connection and nearby continuum behavior. A finite element formulation that includes line-to-line (L-L) and node-to-node (N-N) link elements was utilized. It is applied to interlayer slip specimens and layered beam test specimens. In the latter the degree of composite action is examined by comparing experimental results with rigorous layered finite element modeling of the global systems, with connection modeling included. To date the model is successful within the early limitations enacted for initially simplifying the simulation.