Storebælt suspension bridge -: vortex shedding excitation and mitigation by guide vanes

During the final phases of deck erection and surfacing of the suspended spans of the Storebaelt bridge, vertical deck oscillations of low frequency were observed by workers and supervision staff. The results of on-site monitoring of the oscillations and wind speed measurements at the nearby island of Sprog phi correlated well with wind-tunnel test results obtained during design, indicating that the observed oscillations were due to periodic von Karman, 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 wind-tunnel tests and the design and erection 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. (C) 2000 Elsevier Science Ltd. All rights reserved.