Behavior of dowels in concrete pavements

The contribution of this research project was to simplify beam on elastic foundation theory through matrix formulation and apply these improved analysis methods to dowels embedded in concrete pavements joints. One of these simplifications allows for the analysis of any dowel embedment length greater than about nine inches (229 mm). Dividing the dowel into smaller elements is not required in the solution.;The analytical foundation models represented the concrete with linear-elastic springs. The spring stiffness for each model is given by elastic constants or parameters. Each model predicts slightly different deflection behavior for the embedded dowel based on these parameters. The first model assumes the springs act independently to support the dowel; whereas, the second model assumes interaction between adjacent springs. Modifications were made to the first model to include the effect of pavement thickness which allowed for comparison of both models.;The theoretical bearing stress between the dowel and the concrete was determined based on the fourth derivative of the assumed displaced shape for a particular model. Therefore, the bearing stresses along the dowel-concrete interface are directly related to the corresponding deflections along the dowel within the concrete. The maximum theoretical bearing stress at the transverse joint face was compared to experimental bearing stress. The experimental bearing stress was calculated from the measured deflection of the dowel at the transverse joint face. The maximum bearing stress was limited to some portion of the elastic-limit stress for the concrete medium.;For a given concrete depth below the dowel, as the load on the dowel is increased, the deflections along the dowel within the concrete and the bearing stresses along the dowel-concrete interface will increase. The analyses using the foundation models (described previously) showed, however, that as the medium depth below the dowel was reduced the dowel deflections within the concrete decreased. A decrease in deflection could be explained by the reduction in cumulative compression over the smaller depth. In addition, the analyses by these models showed that as the concrete medium depth below the dowel decreased the contact bearing stress increased. To verify the deflection behavior of dowels embedded in concrete, experimental testing was undertaken for various size steel dowels having either a circular or an elliptical shape.;Three laboratory test methods were modeled using the stiffness method of structural analysis. Two elemental shear test methods and a cantilever test method were modeled. The elemental shear test methods investigated a single dowel that was embedded in concrete on either side of an open transverse joint and subjected to shear loading. The models, based on the assembled stiffness matrix, were used to determine the deflections along the dowel within the concrete and to verify elastic constants for a particular foundation model.;Additional analysis of the elemental shear test specimens allowed for the inclusion of an elastic medium under a portion of the test specimen to model soil-pavement interaction. This analysis was referred to as the three-parameter model which defines a layered system. In this system, the embedded dowel and surrounding concrete are idealized as beams, connected together with springs and the concrete beam is further supported by an elastic medium. (Abstract shortened by UMI.).