DYNAMIC AMPLIFICATION FACTOR AND RESPONSE SPECTRUM FOR THE EVALUATION OF VIBRATIONS OF BEAMS UNDER SUCCESSIVE MOVING LOADS

Analytic expressions of the dynamic amplification factor and the characteristic response spectrum are derived for weakly damped beams with various boundary conditions subjected to point loads moving at constant speeds. These coefficients are given as functions of the ratio of the span length to the loads wavelength, and the loads wavelength respectively. They allow a rapid calculation of the vibration amplitudes induced by a succession of moving loads on a beam. These results are particularly useful in the context of railway bridges preliminary design and assessment of the expected maximum vibration levels under high-speed trains.