The effect of the interface conditions on the dynamic response of a beam on a half-space to a moving load

The classical model of a beam on elastic half-space is adopted as a benchmark model to study the response of a slab–track railway system to dynamic train loading. The focus of the investigation is placed on the effect of the description of the interface between the beam and the half-space on the dynamic response of the track and surrounding soil. Three conventional approaches to this description are addressed, the first two of which are simplified. According to the first approach, tractions are assumed to be uniformly distributed beneath the beam cross-section, whereas the continuity of the beam and half-space displacements is required only along the centre line of the beam. In the second approach, the stresses are still considered to be uniformly distributed across the beam, whereas the continuity is required between the beam displacement and the average displacement of the half-space under the beam. The third approach is the classical approach of contact mechanics, according to which a traction variation across the beam interface is accounted for, whereas the displacements of the half-space are assumed constant under the beam (no torsion is considered). A comparative analysis is carried out of the equivalent dynamic stiffness of the half-space under the beam and the steady-state track and soil response to moving constant and harmonic loads. On the basis of this comparison, applicability domains are established of the three respective interface descriptions.