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RE: Las Vegas Sign Structure

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I attended a talk by Finley Charney about this sign back in 1998.  My notes indicate that a Principal Engineer sealed the drawings but two young engineers with Masters Degrees and with relatively little experience performed the detailed design.  A Peer Review had also been done - but the forensic review team found numerous errors in the design and detailing.
 
Another suggested contributor was the fact that the sign was designed for Exposure Class B (questionable for some quadrants) and a one-third increase was taken for wind.  These served to reduce the safety margin against wind, estimated around 60 mph that day.
 
Bill Sherman
CH2M HILL / DEN
720-286-2792
 


From: Jnapd(--nospam--at)aol.com [mailto:Jnapd(--nospam--at)aol.com]
Sent: Monday, March 03, 2008 3:44 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Sign Structures

Las Vegas area use to have a different philosophy as to awarding contracts and who is responsible.
 
If I remember correctly it was 365' tall and 30' tall x 180-220' long message area at 275' up the sign.
 
I worked for a company that got the contract from the insurance carrier for the contractor of the sign. I will say The structural engineer was told to accept half of his asking fee for the project or he would not get the project. 
His EIT engineer did all the computer input and design. Nodal offsets of 12-18" were not reconized and or ignored.  It failed where our computer model failed.  The iron workers hated to work on it because of the 10-15' of typical movement on any given day. I think it was designed for 30-40' of deflection at top.
 
The city allowed a wind exposure of B old UBC, Las Vegas changed their code requirements after the failure.
 
 
 
In a message dated 3/3/2008 8:16:46 AM Pacific Standard Time, spraguehope(--nospam--at)hotmail.com writes:
Dmitri,
I agree that learning from failures is the traditional and definitive "lessons learned" for structural engineers.  Unfortunately, any significant failure will result in law suits.  Law suits make engineers circle the wagons and most of us are left on the outside wondering what happened. 
 
The few things that I know is that the top 100 feet of the original sign collapsed in July of 1994 and the wind velocities were less than the design load.  A new one was constructed in 1997. 
 
There was litigation that lasted until 2004.  There is an interesting paper that includes a synopsis at:
http://www.folklaw.com/Ethics.htm
The write up source was:
Finley A. Charney, G. Brent Norris, and James Robert Harris, "On the Collapse of the Las Vegas Hilton's Spectacular Sign", Proceedings of the Structural Engineers World Congress, (San Francisco, CA 1998).
 
Finley Charney is a professor at Virginia Tech and Jim Harris has his own business in Denver. 

Regards,
Harold Sprague
 
Joe Venuti
Johnson & Nielsen Associates
Palm Springs, CA