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

A three-dimensional finite element model was used to analyze runway pavement responses under moving aircraft tire loading. The analysis modeled an instrumented runway at Cagliari Elmas airport in Sardinia, Italy, with a 350-mm asphalt layer, a 400-mm granular base layer, and subgrade. The finite element 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 with a nontraditional loading assumption that represented the nonuniform distribution of tire contact stresses along contact length and width under five ribs of an aircraft tire. Analysis results showed that a traditional loading assumption that assumed uniform contact stresses at the tire–pavement interface underestimated 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 caused 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 with the measured responses from field instrumentation. The model results showed that partial debonding between asphalt layers caused much greater tensile strains at the bottom of the whole asphalt layer.