DESIGN OF AIRPORT PAVEMENTS AS AFFECTED BY LOAD TRANSFER AND SUPPORT CONDITIONS

Current FAA Design Criteria for major airports are based on the assumption of edge loading conditions, with an assumed load transfer of 25 percent, and a stabilized subbase equal in thickness to the thickness of the PCC slab. This paper examines the validity and cost effectiveness of these requirements. Theoretical analyses and results from field tests confirm that it is more economical to develop structural capacity of the PCC pavement by increasing the thickness of the PCC slab and reducing the thickness of the stabilized subbase. It is shown that three inches of added thickness in the PCC slab will reduce the deflection of the pavement, the stresses transmitted to the subgrade, and the stresses in the PCC slab more than 12 to 18 inches of stabilized subbase and at a lower initial cost. It is also demonstrated that effective load transfer is needed to prevent excessive corner deflections of PCC slab under the wide bodied aircraft gear loadings. Large diameter dowels and heavy tie bars are used at the load transfer mechanisms. Significant savings were demonstrated using these approaches to pavement design over the thicknesses obtained using the design recommendations in the FAA Advisory Circular.