Modelling highway bridge vibrations: the effect of support conditions

Small-scale flat plates representing flat bridge decks were subjected to forced and free vibration to ascertain their fundamental frequencies, mode shapes and frequency response functions (FRF). Edge conditions were varied by altering the support stiffness and the effects of these alterations upon the vibrations analysed. Plots of accelerance against frequency showed that support stiffness affected the resonances developed: an increase consistent from least stiff spring support to stiffest spring support. As the support stiffness increased, some mode-shapes no longer appeared in the FRF. Forced vibration testing showed an increase in support stiffness to effect the dissipation of vibrations as they traversed the plate.