Shear response, deformations, and subgrade stiffness of a dowel bar embedded in concrete

The design of shear-carrying structures very often profits by the dowel action developed by reinforcing bars or shear connectors, since dowel action is, in principle, a very efficient shear-transfer mechanism. Within the same element, the reinforcing bars may act as dowels as soon as stress-induced interfaces form (cracks in the ultimate load situation), while shear connectors between side-by-side elements (studs, pins, dowels) develop a dowel action from the very beginning of the loading process, including the service load situation. Within this framework an experimental program has been carried out to investigate the dowel action in 27 reinforced concrete specimens fitted up with a single deformed bar of 14, 18, and 24-mm diameter (No. 5, 6, and 8). The shear response of the dowel bar, the displacements and curvatures up to failure, and the subgrade stiffness of the concrete embedment were measured or evaluated. The tests give new evidence on the behavior of dowel action and allow further checks of the models available in literature for predicing dowel strength and stiffness. Furthermore, suitable formulations are proposed for the subgrade stiffness of the concrete embedment to allow the professional engineer to design a dowel bar or introduce dowel action in a safer and more consistent way