Effect of the relative differences in the natural frequencies of parallel cable-stayed bridges during interactive vortex-induced vibration

This study was focused on the effects of vortex-induced vibration (VIV) in parallel twin cable-stayed bridges. A series of wind tunnel tests were performed to investigate the effect of the relative differences in the setup of the natural frequencies of parallel decks during VIV. The differences in the natural frequencies of the two decks are represented in terms of the frequency ratio (FR) as defined by the ratio of the natural frequency of the upstream deck to that of the downstream deck. Six FRs were examined to cover all the potential ranges of relative differences in the natural frequencies of the two decks. The interactive motions of the two decks were examined with normalization parameters to demonstrate the fundamental mechanics of complicated VIV of parallel twin cable-stayed bridges from the viewpoints of fluid and structural dynamics.