Development of a Computer Program to Compute pavement Thickness and Strength

Computer Applications to Airport Pavements

A computer program was developed for computing flexible and rigid pavement Aircraft Classification Numbers (ACNs) according to Annex 14 of the ICAO Airport Pavement Design Manual. The computer subroutines listed in Appendix 4 of the ICAO manual have been implemented in the computer program, and it was shown that these implementations accurately reproduce the ACNs computed by the ICAO programs. The program contains an internal library of aircraft covering most of the large commercial and military aircraft currently in operation and those included in the ICAO manual. A new aircraft configuration can be added to an external library. The user of the program can also modify airplane gear configurations by adding and removing wheels or moving wheels to any arbitrary location. The computer program also has the capability of calculating flexible and rigid pavement thicknesses. In the case of rigid pavements, calculation of slab thickness implements the Portland Cement Association (PCA) method based on slab interior stress or implements the Federal Aviation Administration (FAA) Westergaard edge stress procedure as is implemented in the design charts in Advisory Circular (AC) 150/5320-6D. Two triple twin tandems closely spaced were analyzed. It has been found that the influence of the second twin tandem on slab thickness is negligible based on the H51 model implemented in the computer program.

Authors: Izydor Kawa, Gordon F. Hayhoe