Implications of Using Different Interface Friction Models on the Evaluation of Rigid Pavement Structures

Pavement evaluations provide airfield management teams with estimates of the structural capacity of their airfields. These pavement evaluations include computation of allowable passes and allowable gross loads using layered elastic analytical techniques. In its airfield evaluation criteria, the Department of Defense recommends the use of the computer program PCASE. Currently, PCASE uses the layered elastic code WESLEA, but future versions of the program will transition to another layered elastic program JULEA. These two LEA codes contain different interface models to describe the bonding condition between pavement layers. The definition of this relationship is important when considering the interface at the bottom of slabs in rigid pavements. The purpose of this study is to quantify the differences in computed bending stresses, allowable passes, and allowable gross loads (AGLs) in the evaluation of concrete airfield pavements using the two interface bonding definitions. The theoretical formulation of these two interface models shows that an essential shortcoming in WESLEA is its lack of consideration for the interfacial shear stresses. Results show that this fundamental difference in the interface definitions leads to noticeable disagreements in estimations of bending stress, allowable passes, and AGLs by the two programs. Findings suggest that the JULEA interface model provides a sounder theoretical relationship for interface bonding and should be used in future versions of PCASE.