Vortex shedding excitation of the Great Belt suspension bridge

During the final phases of deck erection and surfacing of the suspended spans of the Great Belt East Bridge low frequency vertical deck oscillations were observed by workers and supervision staff. The results of on-site monitoring of the oscillations and wind speed measurements at the near by island of Sprog0 correlated well with wind tunnel test results obtained during design, indicating that the observed oscillations were due to periodic von Kármán type vortex shedding in the wake of the girder. The present paper discusses the results of the on-site structural and wind monitoring programme, correlation to the wind tunnel tests and the fitting of guide vanes to the main span girder for mitigation of the oscillations. The vortex induced oscillations were found to be harmless from a structural point of view but unacceptable considering possible physiological impact on users of the bridge.