Modeling of Flexible and Rigid Pavements under Aircraft Loading
AdvisorSebaaly, Peter E.
Civil and Environmental Engineering
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The Federal Aviation Administration (FAA) is currently using linear elastic theory (LET) and finite element (FE) modeling for calculating pavement responses in its FAARFIELD software for flexible and rigid pavements, respectively. LET is also used in the BAKFAA software for backcalculating layers moduli of flexible and rigid pavements. The proposed research aimed at evaluating various pavement analysis and backcalculation models by comparing their calculated responses to the measured responses from instrumented sections at the National Airport Pavement Test Facility (NAPTF). To accomplish the research objectives, an extensive literature review was performed, a work plan was developed to evaluate measured responses from Construction Cycle One (CC-1), and pavement modeling was performed to generate responses for comparison with the measured values. Backcalculation was also performed to determine the in-situ layers moduli using various models. The evaluated models included the Odemark-Boussinesq (OB) model in the ELMOD software, and the linear elastic theory model in the ELMOD and BAKFAA software. In addition, a new dynamic finite element model was developed and used for backcalculation. The new model addresses the subgrade’s apparent non-linearity captured during Falling Weight Deflectometer (FWD) testing, which was shown to be related to the subgrade layer damping that can be approximated using the Rayleigh damping parameters. The new model produced reliable moduli for all layers, as compared with the other models. It is therefore recommended to further develop the new model for use in the BAKFAA software.The responses from the CC-1 dynamic sensors were extensively evaluated in this project, including; pressure cells, strain gauges, and multi-depth deflectometers for the flexible test items and strain gauges for the rigid test items.The backcalculated layer moduli using the new model were used as input in the 3D-Move and ABAQUS software to predict the pressures, strains, and deflections for the flexible test items, and were also used as input in the FEAFAA software to predict the strains for the rigid test items. The measured responses were predicted by the 3D-Move and ABAQUS models with high reliability.