IMPORTANCE OF SPEED AND FREQUENCY IN FLEXIBLE PAVEMENT RESPONSE

This paper examines the importance of structural dynamics in the prima ry response of flexible pavements to fluctuating, moving wheel loads. The influence of vehicle speed and loading frequency are examined firs t, using a validated dynamic road-response model with idealized loads. The dynamic calculation procedure is then simplified to provide a ''q uasi-dynamic'' calculation which accounts for vehicle speed but not th e dependence of road response on loading frequency. The simplification decreases the necessary computer resources significantly and reduces the computation time sufficiently for use on a personal computer. The validity of the simplification is tested by comparing primary road res ponses and fatigue damage predicted by the two methods, for dynamic wh eel loads generated by two representative mathematical vehicle models, on two different roads. It is found that differences in response are observable, but in practical situations they are likely to be small. I t is concluded that the simplified quasi-dynamic calculation approach is preferable.