On the 1st November 1965, during high winds, three out of a group of eight cooling towers at Ferrybridge ‘C’ Power Station collapsed, with the remaining towers sustaining severe structural damage.  The towers, each 375 feet high, had been constructed closer together than was usual and had greater shell diameters and shell surface area then any previous towers. The design and construction contract for the towers had been given to Film Cooling Towers (concrete) Ltd. in 1962.

High winds were considered to be the trigger for the collapse, but an inquiry found  the exact cause to be an amalgamation of several other factors in their design:

  • British Standard wind speeds had not been used in the design resulting in the design wind pressures at the top of the tower being 19% lower than it should have been.
  • Basic wind speed was interpreted and used as the average over a one minute period, whereas, in reality, the structures are susceptible to much shorter gusts.
  • The wind loading had been based on experiments using a single isolated tower.  The grouping of the towers created turbulence on the leeward ones – the ones that did actually collapse.
  • Safety margins had not really covered any uncertainties in the wind loadings.

There had been, it was decided, a serious underestimation of the wind loading in the initial design.

Fortunately, no one was killed or injured in the accident.

Ferrybridge Cooling Tower Collapse Ferrybridge Cooling Tower Collapse
A cooling tower comes crashing to the ground during high winds at Ferrybridge ‘C’ Power Station in 1965. The aftermath of the incident. Three
of the eight cooling towers were
completely destroyed.
The vibrations of slender structures are caused by cross-wind loads known as the phenomenon vortex shedding. Specific critical wind speeds around an object can create under and over pressures that makes it move (vibrate) in cross-wind direction. These forces can make bridges swing  , and chimneys or similar slender and light structures oscillate. Oscillation occur when the damping is small and the natural resonance frequency is close to the vortex shedding frequency.
About these ads

4 responses »

  1. Cooling tower condenser systems are designed to throw out the heat from the medium (usually water) used to condense refrigerant gas in either an open-circuit or closed-circuit configuration.

  2. Dr. N. Subramanian says:

    I want to use the images in my book on Design of RC structures.Can you give permission or give me the source?

  3. Tony says:

    This is a good explanation of the collapse. I analysed the structures post collapse, and concluded that a single tower without the complexities of adjacent towers would have reinforcement stresses exceeding yield at a wind speed of approximately 68 mph. On the day of the collapse, the station anemometer was indicating gusts of 72 mph.

    I designed the strengthening works for the remaining 5 towers, and supervised the rehabilitation project.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s