The influence of gantry rails on twin-box deck aerodynamics

The present paper reports on wind tunnel tests and CFD simulations, carried out to investigate the effects of gantry rails on the aerodynamic performance of a twin-box bridge deck section. It is found that the aerodynamic performances, in terms of vortex induced vibration and flutter speed, of the analysed twin-box deck equipped with gantry rails is better than the similar girder without gantry rails. The increase in flutter stability is mainly due to the positive moment coefficient at zero angle of attack which leads to nose-up rotation under wind action, ensuring that the elastically suspended deck meets the wind at ever increasing angles of attack. Furthermore, flutter stability increases for a positive slope of the static moment coefficient, that is decreasing for increasing angles of attack.