Validation of the Dynamic Amplification Factor in Case of Historic Railway Steel Bridges with Short and Medium Spans

One of the significant parameters in design as well as fatigue assessment of railway bridges is the dynamic factor. The dynamic factor, also called dynamic amplification factor (DAF), must be applied to the static load model in order to take account of dynamic magnification of stresses and vibration effects in the bridge. The dynamic factor which actually enhances the static load effects depends on many parameters that are difficult to take into account with reasonable accuracy. The maximum bridge-span, train speed, self-weight, expansion joints if any is placed in bridge, the type of bridge supports and finally soil-structure interaction are among these parameters. This paper studies the variations of the analytical and experimental observations on steel railway bridge dynamics. For this purpose the measured stresses due to passing a locomotive through a historical steel railway bridge in Germany are compared with the calculated stresses contemplating the dynamic factor proposed by EN1991-2 ^[1] applied to the static load model of the same locomotive.