Prediction of aeroelastic stability of suspension bridges during erection

During erection of long-span suspension bridges the stiffening girder lacks torsional continuity. Thus, it becomes important to consider flutter-type aeroelastic instabilities. During the early stages of deck erection, the critical wind speed for onset of flutter becomes particularly low and in this case it may prove interesting to consider flutter control by provision of eccentric ballast. The present paper extends standard bridge flutter routines based on measured aerodynamic derivatives to include the effect of eccentric deployment of ballast. The potential enhancement of the critical wind speed by this method is discussed and the importance of applying actual measured aerodynamic derivatives for the bridge section in question is emphasised as opposed to the use of theoretical "flat plate" aerodynamic derivatives.