A simpler way to predict bridge flutter

March 2012

Research engineers in Italy have come up with a new, simplified method for predicting the onset of bridge flutter – the potentially catastrophic oscillation of slender bridge decks above a critical wind speed. The method is reported in the latest issue (165 SB3) of the ICE’s Structures and Buildings journal.

According to lead author Claudio Mannini of the University of Florence, ‘Modern long-span bridges are more and more sensitive to wind loads and aeroelastic phenomena. An adequate and reliable safety margin with respect to the critical wind speed leading to flutter, which induces catastrophic oscillations and even collapse of the structure, has to be guaranteed.’ 

Classical and torsional flutter – the latter being the cause of the famous 1940 Tacoma Narrows suspension bridge collapse in the USA – is usually predicted with complex, semi-empirical models. The new method uses just three aerodynamic coefficients instead of the usual eight.

‘This approach may be seen as an easy engineering tool for a better tailoring of bridge structures at early design stages,’ says Mannini. 'In addition, the simplicity of the equations allows better understanding of the mechanism of flutter stability and the role played by structural parameters such as damping.' 

For more information please contact the ICE Proceedings editor Simon Fullalove at editor@ice.org.uk or telephone +44 20 7665 2448.