Characterization of Fatigue Looseness of Dowel Bars Based on Substructure Experiment

Abstract

Dowel bars are indispensable parts of the concrete pavement for load transfer, but they become looser under repetitive load. Because the actual shape and magnitude of fatigue looseness of dowel bars were not observed well through experiments but are usually presumed under insufficient evidence, the article presents an experimental investigation on the dowel bar-concrete substructure, and two indexes, DL1 and DL2, are proposed to characterize the looseness of the dowel bar. DL1 is one-dimensional, and DL2 is two-dimensional. DL1 and DL2 both have a good logarithmic relationship with the number of load cycles. By varying the test parameters, the influencing factors of dowel bar looseness were found, such as dowel bar diameter, concrete grade, anticohesion layer, and others. The index DL2 is more comprehensive than DL1 because the regression fitness of DL2 is better than DL1 and because DL2 is the best failure criterion among four candidates. The relationship of dowel bar looseness with load transfer efficiency (LTE) also shows the necessity of introducing DL2.