Dynamic effects in concrete airport pavement joints

The use of computational mechanics in the analysis of dynamic-interaction phenomena is going to be very widespread, and constitutes too a sound opportunity to deal with problems of an application nature. In particular, this approach can be used to study, in innovatory fashion, the dynamic interaction between aircraft landing gears and airport pavements, since, relative to the methods traditionally adopted, it is more suited to representing the real conditions of the problem. Finite-element analysis can be used to evaluate the contact forces and the stresses in the landing gear and in the pavement, due account being taken of the dynamic effects. This paper describes the development of a three-dimensional finite-element model that represents an aircraft landing gear and a concrete airport pavement with joints between adjacent slabs outfitted with, or devoid of, load-sharing dowels. The model was developed to evaluate the level of the dynamic effects in airport concrete-pavement joints, in particular when stepping comes about between adjacent slabs, i.e. differences in their surface elevations. A parametric analysis was carried out, elevation differences and aircraft speeds being varied, and using dowelled and undowelled pavements. Thirty-two simulations were then carried out (four different speeds, four different elevation differences, and two types of pavement). The results of the tests made with undowelled pavement, expressed in terms of relative displacements between adjacent slabs, were used to evaluate the efficiency of the joint during load transfer (LTE, Load Transfer Efficiency). The results of tests carried out with dowelled pavement, expressed in terms of stress state, were compared with the corresponding values taken from Westergaard’s theory and with those obtained by applying another finite-element model, published by the FAA (Federal Aviation Agency), which takes no account of the described dynamic effects.