Behavior of dowels in concrete pavements

Abstract

Concrete structural elements such as wall sections, bridge abutments and slabs on grade rely on dowels to transfer loads across the joints. As the joint width becomes wider, or if the joint is formed, the effect of aggregate interlock to transfer load is reduced and the loads are transferred by dowels. The dowels can be circular or elliptical shaped and are more commonly made of steel or Fiber Reinforced Polymer (FRP). This research project considered steel dowels with either a circular or an elliptical shape used in a highway or airport pavement. The following linear-elastic analysis, however, can be used for FRP dowels and for other doweled structural elements. Dowels are spaced along transverse joints in a highway or airport pavement. The dowel’s main purpose is to transfer shear load across the joint which separates adjacent concrete slabs. Dowels are approximately eighteen inches (457 mm) long, placed at midheight of the pavement thickness, positioned parallel to the pavement surface, and embedded symmetrically about the transverse joint centerline. The transverse joint was assumed to open, and its width is dependent on the combination of concrete shrinkage and slab contraction due to colder temperatures. Wheel loads from a single axle, positioned along the open transverse joint, apply a shear load to each effective dowel along the joint. Effective dowels are those dowels included in the distribution of the wheel loads. The shear load causes the dowels to bear against the concrete and causes the dowels to deflect within the concrete. These deflections are directly related to the bearing stress between the embedded dowel and the concrete (or contact bearing stress). The maximum bearing stress corresponds to the maximum deflection which occurs at the transverse joint face. If the maximum bearing