Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Phenomenon seen beyond bridges

Letters

The question of predictability of the nature of the lateral motions of the Millennium Bridge will doubtless provide a subject for a full debate in due course.

The phenomenon of 'locking-in' of the frequency of the disturbing force, when this approximates to the natural frequency of the structure, occurs elsewhere.

For example, this is also a feature of the vortex stream for a cylinder in a steady current of air or water.

Another similarity is that here also the transverse oscillation caused by the vortex-shedding, which corresponds to the lateral motion of the bridge, will have a natural frequency half that of the rarer in-line oscillation, observed by Sainsbury and King at the Immingham Jetty (Proceedings of the ICE 49, 269-302), which corresponds to the vertical motion of the bridge.

Sir Alan Muir Wood (F), Franklands, Bere Court Road, Pangbourne, Berks, RG88JY

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.