DYNAMIC RESPONSE OF FINITE SIZED ELASTIC RUNWAYS SUBJECTED TO MOVING LOADS: A COUPLED BEM/FEM APPROACH

SUMMARY The transient response of a finite elastic plate, resting on an elastic half-space, and subjected to moving loads is considered here. Both the cases of an elastic foundation alone, as well as a finite sized elastic plate resting on an elastic foundation are considered. The numerical methods employed are: (1) the time-domain boundary element method for the elastic foundation and (2) a combination of the time-domain boundary element method for the soil and the semi-discrete finite element method for the finite sized elastic plate. Both constant as well as linear-time-interpolation schemes are included in the BEM. The integration is carried out analytically in time. The analytical solution for a moving point load on an infinite elastic plate resting on an elastic half-space is derived here. This is used as a benchmark against which the present numerical solution is compared with. The accuracy of the numerical method is also verified by comparing the solutions with some existing numerical results; the comparison with the solutions based on a Winkler foundation model reveals the limitations of the applicability of such a model, especially in the cases of high velocities of the moving load. This is because neither the inertia of the foundation, nor the behaviour of the foundation as a continuum, can be properly accounted for in Winkler’s model. A parametric study is conducted, and the influences of velocity of the moving load, load distribution, etc. on the dynamic response of the soil/runway system are investigated. Furthermore, the present computational method is applied to the problem of a transport airplane taxiing on a concrete pavement resting on a typical soil. The responses of pavements are presented for different taxiing velocities.