Effective maintenance of concrete pavements requires precise evaluation of the load transfer at transverse joints. The load transfer is evaluated from the load transfer efficiency (LTE) that is simply calculated from the deflections at the loaded and unloaded slabs. The LTE is supposed to strongly depend on dowels, crack width, and base course and subgrade stiffness. In Japan, less than 65% LTE is considered unsound and directly leads to repair of the joint. Thus LTE evaluation is very important in the maintenance activity. This study investigates the effects of dowel properties, base course and subgrade stiffness and a gap underneath the slab on the joint performance based on a back-analysis of FWD measurement data. FWD deflections are simulated for various elastic moduli of the asphalt interlayer, base course and subgrade in the degrading process with three dimensional finite element models, creating a database of FWD deflections, elastic moduli and stages. Using the database, the state of a joint structure can be identified from a measured FWD deflection curve. The result of the analysis provides not only elastic moduli of the layers but also the stage of degradation of the joint structure to help engineers to determine a proper rehabilitation measure. The method was validated on an existing concrete pavement, on which FWD testing was conducted before being open to traffic and after several years in service. The validation revealed the possibility that the degrading stage of a joint can be detected directly from LTE and measured deflections without the back-analysis. It was also investigated how the state of the degrading joint affects the stress of concrete slab. |