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RE: We're Not Getting Older, We're Getting DUMBER

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I emailed Mike. He's checking to se how his name was involved, but he
provided this information (a copy of an article) about what the reference
was to. It looks like it was the load side, not the resistance side, that
had the effect of causing the collapse.

Bob Shaw

Ferrybridge Cooling Towers Collapse

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
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
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.

-----Original Message-----
From: Gary Hodgson & Associates [mailto:ghodgson(--nospam--at)] 
Sent: Thursday, January 26, 2006 8:16 AM
To: seaint(--nospam--at)
Subject: Re: We're Not Getting Older, We're Getting DUMBER 

I recently quoted a transmission tower that failed when
designed by ASD where they say it probably would not
have failed if designed by LFRD.  My source (they) was
Mike Gilmor at the Canadian Institute of Steel
Construction-phone 416-491-4552.

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