Three-Dimensional Finite Element Modeling of Instrumented Airport Runway Pavement Responses

The objective of this paper is to analyze runway pavement responses under moving aircraft tire loading using a developed three-dimensional (3-D) finite element (FE) model. The instrumented runway at Cagliari-Elmas airport (Sardegna, Italy) was modeled in the analysis, which consists of a 350-mm asphalt layer, a 400-mm granular base layer, and subgrade. The FE model characterized the asphalt layer as a linear viscoelastic material, and two interface bonding conditions between asphalt layers (full bonding and partial debonding) were used in the analysis. The aircraft tire loading was simulated using a nontraditional loading assumption that represents the non-uniform distribution of tire contact stresses along contact length and width under five ribs of an aircraft tire. Analysis results show that traditional loading assumption that assumes uniform contact stresses at the tire-pavement interface underestimates the critical tensile and shear strains in the asphalt layer. In particular, the relatively high contact stresses at tire edge ribs under heavy aircraft loading cause significant shear stresses at the pavement near-surface. The pavement responses under various loading conditions (aircraft type, wheel load, and speed) were calculated, and the critical responses were identified. Good agreements were achieved when the calculated pavement responses (vertical pressure and horizontal strain) at various locations were compared to the measured responses from field instrumentation. The model results show that partial debonding between asphalt layers causes much greater tensile strains at the bottom of the whole asphalt layer.