FLEXIBLE PAVEMENT MODEL VESYS IV-B

Various capabilities of several versions of the VESYS flexible pavement model have been combined into a single computer program called VESYS IV-B. The resulting computer program was also edited and modularized to make it more convenient to use and to modify in the future. VESYS IV-B now models an n-layer flexible pavement structure using resilient moduli, creep compliance, or a combination of these for specifying layer stiffnesses, which may be varied seasonally. Both single and tandem axles are considered. Both fatigue and permanent deformation material properties may be varied seasonally, and permanent deformation properties and layer moduli may be varied with magnitude of loads as well. Seasonal variations in the fatigue constants K1 and K2 may be generated internally on the basis of seasonal pavement surface temperatures or stiffnesses. This state of the art model predicts fatigue cracking, rutting, and serviceability loss. These revisions and improvements are described in the report, and a combined keyword dictionary and input guide is included. (FHWA)