Effects of the overhang length on the vortex-induced vibration response of bridge decks Available to Purchase

The effect that a splitter plate placed in the wake behind a bluff body has on the vortex-induced vibrations (VIV) is well recognised in the literature. This study explores whether similar effects are caused by long cantilevered extensions found on some bridge decks. The analysis employs two-dimensional Reynolds-averaged Navier–Stokes equations, prescribed motion computational fluid dynamics simulations coupled with the energy balance approach to investigate the VIV response of a set of bridge decks with varying overhang lengths. It was found that with increasing overhang length, the displacement amplitude due to vortex shedding drastically decreased. The studied deck sections exhibited a reduction of 75% in the maximum displacement amplitude when compared to the section without the overhang. A similar decrease was observed in the lock-in region width. For the sections with longer overhangs, oscillations in the wake characteristic of motion-induced vortices have been observed. These oscillations occurred at larger displacement amplitudes than those related to Karman vortex shedding by a factor of 4.5 and occurred only after an initial sustained perturbation in the displacement amplitude. Finally, the sections with longer overhangs displayed higher susceptibility to the changing Scruton number, highlighting the importance of modelling the correct damping level when committing to wind tunnel tests.