Stress-Prediction Model for Airport Pavements with Jointed Concrete Slabs

Abstract: Two specific three-dimensional finite-element models are presented for making an evaluation of the maximum stresses at critical locations in concrete slabs i.e., at the interior and edge that is superior to the classic approach of the approximate methods. Concrete airport pavements with square-shaped slabs are studied. A homogeneous, isotropic elastic half-space is assumed as a subgrade foundation model so that the influence of variation in Young’s modulus is examined in contrast with Winkler’s reaction modulus. The effects of two aircrafts A380 and B747, different subgrade bearing capabilities and temperature gradients Δt, are investigated. Combined stresses due to aircraft load and temperature gradient Δt are accurately estimated by means of a finite-element software and compared to their separate actions. As a consequence the incorrect applicability of the principle of effects superposition, which is due to the support soil that is non resistant to tensile stress, is quantified. Moreover, the difference in the values of the stresses due to the two different aforementioned aircrafts is calculated. A simplified method for predicting maximum stresses is also derived from the results of the finite-element software. This predictive method represents a useful tool for a faster estimation of stresses at a preliminarily design level. The proposed equations make adjustments to Westergaard’s load stress model and Eisenmann’s temperature stress model necessary, as they also do for the separate actions of load and Δt. The procedure makes use of dimensionless variables so that it may also be extended to different square-slab dimensions.