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

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If the quoted article is correct, the structure was a cooling tower, not
a transmission tower.  I have a hard time believing that a transmission
tower (antenna-supporting towers are similar, different design standard
and configuration) would FAIL by the use of one design method versus
another.  Tower failures occur mainly due to substandard materials,
incorrectly determining or applying wind forces or due to soil issues.

Dave K. Adams, S.E.
Lane Engineers, Inc.
Tulare, CA
E-mail:  davea(--nospam--at)laneengineers.com




-----Original Message-----
From: Robert E Shaw Jr [mailto:rshaw(--nospam--at)steelstructures.com] 
Sent: Thursday, January 26, 2006 8:04 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: We're Not Getting Older, We're Getting DUMBER 


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
SSTC

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 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.




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

Chris,
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. Gary



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