Observation of vortex-induced vibrations on a cable-stayed bridge

Vortex shedding is an important serviceability issue for slender structures, as it may cause moderate but sustained response at low wind speeds. While a great deal of valuable information has been gained through wind-tunnel testing of typical bridge sections, the number of observations of vortex-induced vibrations on prototype bridges is limited. This paper will present observations of vortex-induced vibrations on a twin-deck cable-stayed bridge, obtained during a six-year long-term measurement program. The specific objectives of this paper are: (i) to discuss several criteria that can be used to identify vortex-induced (locked-in) response from full-scale measurements, (ii) to present examples of vortex-induced events captured during the program, and (iii) to interpret some of the observed behavior using wind tunnel experiments on sectional models.