Effects of dowel misalignments on concrete pavement joint opening behavior

An experimental and analytical investigation on the effects of misaligned dowel bars on the opening characteristics of transverse joints in concrete pavement is presented in this thesis. Experimental investigations were conducted to determine the joint opening behavior of concrete pavements fitted with misaligned dowel bars. The parameters included in the experimental investigations were the number of dowel bars at the joint, the dowel misalignment type (horizontal, vertical, and combined), misalignment magnitude and orientation across the joint. The results from the experimental investigation indicate that: (1) all pavement joints are initially locked, and opening displacements occur after the pullout force per dowel exceeds 1124-1574 lbs, or the average bond shear stress exceeds 32-44psi. (2) For all misalignment types, the pullout force per dowel increases with larger misalignment magnitudes, non-uniformity and number of dowels at a joint. (3) Structural distress in the form of concrete spalling and transverse cracking was observed for specimens with larger dowel misalignments and non-uniformity. These experimental results do not provide comprehensive knowledge regarding the mechanics of dowel-concrete interaction, and an analytical investigation was carried out to address this limitation.; In light of the limitations associated with the experimental investigation, three dimensional (3D) finite element (FE) models for computing the stress states and resulting damage in concrete pavement joints with misaligned dowels, and their validation using experimental results were developed. The results from these models compared reasonably well with the experimental data and the FE models provide significant insight into the 3D stress states and principal stresses that develop in concrete pavement joints with misaligned dowels. They are used to evaluate analytically the effects of misalignment type, magnitude, uniformity, and distribution on the 3D stress states and resulting damage in concrete pavements. The analytical results (3D stresses and strains) from the finite element analyses were considered to identify significant events or material damage limit states in the concrete pavement joints. Parametric studies were conducted on a single and two dowel bars by changing the misalignment magnitude, type and orientation. Horizontally misaligned dowel bars were found to be more detrimental than vertically misaligned dowel bars in the single dowel bar FE model. The effects of a non-uniform vertically misaligned dowel bar were more detrimental compared to uniform or alternate misaligned bars. Recommendations on misalignment tolerances were made based on the assumptions and limitations from the experiments and FE models. A preliminary 3D FE analytical study was conducted on the effects of typical misaligned dowel bars combined with wheel loading. The study involved using the recommended misalignment magnitudes, joint opening and assumed loading. The results from the study showed that misaligned dowel bars by itself did not cause detrimental effects in concrete.