It was a windy day on 1 November 1965. In the morning, three of the eight cooling towers at Ferrybridge Power Station in the UK collapsed. Later investigations showed that vortex shedding behind the four remaining towers (a Kármán vortex street) generated wind forces far higher than those typical for the area – and overloaded the 130 mm thick walls of three towers, which then came down.
New designs of towers, circular tanks, masts etc. must take into account the effects of vortex resonance – for more information see Eurocode EN 1991-1-4 E.1.5.2.7.
Unfortunately, a good deal of engineering knowledge has grown out of the mistakes we have had to make. Fortunately, more and more of them can be headed off with simulation tools such as Dlubal RWIND.
