CRITICAL SPEEDS AND THE RESPONSE OF A TENSIONED BEAM ON AN ELASTIC-FOUNDATION TO REPETITIVE MOVING LOADS

A finite-length tensioned beam on a damped elastic foundation is acted upon by an infinite series of equally spaced and steadily moving conc entrated transverse loads. The deflection response of the beam is obta ined by an expansion in terms of the normal modes of vibration. Numeri cal results are determined for various values of the load-spacing, bea m tension, foundation stiffness and damping, and for a range of load-s peeds. It is found that the critical velocities fdr repetitive loading exist at significantly lower speeds than would be expected based upon the well-known critical speed for a single moving load. An interpreta tion in terms of forced vibration response is given.