A NONLINEAR MECHANISTIC MODEL FOR DOWEL LOOSENESS IN PCC PAVEMENTS

Abstract

This paper describes a nonlinear mechanistic model that was developed to simulate the behavior of loose (or nonuniformly supported) dowel bars in rigid pavements. This model can be used in conjunction with other structural models to predict the responses of portland cement concrete (PCC) pavement to loads when various degrees of dowel bar looseness or loss of support exist. Numerical examples are presented to demonstrate that longitudinal flexural stresses, which produce transverse cracking, are sensitive to the degree of dowel bar support. These examples indicate that each increase of 0.076 mm (0.003 in) looseness can produce a 10% increase in the maximum load-related stress at the pavement edge, a 14% increase of the maximum load-related stress at the middle of the slab, and a 14% decrease in load transfer efficiency. For PCC pavement thickness design procedures that are based on fatigue criteria, this additional longitudinal stress can be significant. These results indicate that steps must be taken during construction to minimize initial dowel bar looseness, as has been suggested by many investigators. Research is needed to further quantify the effects of dowel bar looseness on concrete pavement behavior and performance with respect to the results of previous studies that were conducted assuming uniform dowel bar support.