Recent observations in bridge deck aeroelasticity

The Deer Isle Bridge, opened for traffic about the same time as the old Tacoma Narrows Bridge, has a deck section shape which resembles that of the ill fated bridge. Because of the Tacoma Narrows experience, various structural stiffening systems were added to the Deer Isle Bridge to alleviate the type of wind response that destroyed its contemporary. In addition, the Deer Isle Bridge deck is also provided with open-grate vents to improve its aerodynamics. The Deer Isle Bridge remained active under wind even with these modifications, though an earlier study has confirmed the efficacy of the structural modifications in stiffening the bridge. It has been the subject of an extensive field survey by the Federal Highway Administration for the last several years. The present paper summarizes the results of a wind tunnel investigation of a two-dimensional scale model of the Deer Isle Bridge deck, new techniques used in the experiments and the conclusions drawn therefrom on the aeroelasticity of these bluff sections. This forms a part of a comprehensive study centered on the field experiments on the Deer Isle Bridge.