Effects of Turbulence Length Scale on Wind-Induced Response of Bridge Section

Abstract

In this study, the effect of turbulence length scale on vortex induced vibration (VIV) and buffeting response of a twin deck bridge section was evaluated by wind tunnel experiments. Utilized bridge section was a 1/100 scale model based on an actual twin deck bridge section. The target wind power spectra was generated based on actual topographic conditions. Several wind turbulence conditions were generated by the use of active turbulence generator (ATG). At lock-in wind speed, the root-mean-square (RMS) amplitudes of the vortex-induced vibration (VIV) of the bridge section were determined under laminar condition and at different turbulent wind conditions. For the buffeting response, RMS amplitudes were recorded at two wind speeds under different turbulent wind conditions. Experimental results show that for the given twin-deck section, the turbulent wind decreases the RMS amplitude of the VIV as compared to laminar flow. And as the turbulence intensity increases, response RMS amplitude decreases. However for a given constant intensity, the turbulence length scale did not show any effects on the VIV RMS amplitude. Wind tunnel test results demonstrated that the buffeting response of the bridge for a given wind speed and turbulence intensity is influenced by the turbulence length scale. And an increase in turbulence length scale decreases the buffeting response of the bridge. This result was verified in the numerical analysis by the use of in-house buffeting program.