Evaluating the Effect of Concrete Slab Curling on Joint Load Transfer Responses

摘要

Past and current rigid pavement thickness design procedures used by the FederalAviation Administration (FAA) use single-slab free-edge loading stress analysis as the basis ofdesign. A 25% reduction in free-edge bending stress to account for the ability of properlydesigned joints to transfer load from slab to slab and reduce bending stress caused by heavywheel loads has been assumed in the FAA’s rigid pavement design methodologies. In reality,this percentage reduction is continuously changing as a function of slab temperature, joint type,pavement age and traffic. This paper presents a systematic procedure used to evaluate the jointload transfer percentage stress reduction factor in greater detail using FWD measurements, slabcurvature measurements and the finite element method of structural analysis. Fieldmeasurements of joint stiffness and slab curling are presented and compared to FEM simulationscalibrated to reproduce field measurements. Using calibrated FEM models, the full range ofexpected load transfer percentages are demonstrated for single wheel loads, two-wheel gears andfour-wheel gears for a wide range of possible joint stiffness values. Top-down and bottom-upcracking stress profiles are compared. Measured slab curling from test sites is compared tocalculated slab curling from FEM models. This paper demonstrates how to calibrate an FEMmodel to reproduce detailed site FWD measurements of joint stiffness and slab curvature.