Pavement Shear Strain Response to Dual and Wide-Base Tires

Abstract

FHWA conducted controlled loading tests on the US-23 test road in hot weather conditions in Ohio. The tests used four tire types in both dual and wide-base configurations, which were fitted on a single unit two-axle truck, maintaining a constant gross vehicle weight. Two pavement sections, one 8 in. (200 mm) and one 4 in. (100 mm) thick, were instrumented with strain gauge rosettes oriented vertically to measure strain traces induced from the passing wheel loads at three speeds and tire inflation pressures. Pavement temperature was monitored with depth during testing as well as wheel track offset distance from the strain sensors. Because of time constraints, only the sensors in the plane parallel to the direction of loading were analyzed, and response data were compared only with linear elastic pavement response models. The as-measured data were processed and evaluated for all rosettes oriented in the direction of loading. Stress relaxation modulus data were used to adjust the pavement modulus to a common temperature and loading time so all measured data could be compared at the same loading conditions. The WinLEA linear elastic model was used to determine the relationship of structural modulus to strain. Lateral offset distributions were determined from measured data to adjust all strains to the offset where maximum strain response is observed in the as-measured data. The adjustments were then applied to the as-measured strain data to make consistent comparisons between tires. Three of the four tire configurations produce nearly equivalent pavement response, which was attributed to similarities between the tire footprint widths.