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Dallas Cowboys indoor practice facility collapses

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JAE and Hokie:

Are sure that the article did not mean that "Summit did not supply (the name of) the engineer of record"?

Under the circumstances, it could either mean that there was none, or that Simmit chose not to divulge it, if he is an employee of theirs.

Mike McCann
MMC Engineering
 
It could be interpreted in different ways, but JAE quoted correctly from the news article.
 
The Texas A&M spokesman was being disingenous at best. While A&M did not contract directly with Summit, Summit designed, engineered, stamped and installed the two structures at A&M. The project was run through a GC and Summit's contract was with the GC, so technically the school can say that they did not have a contract with Summit for the work, but the work was definitely done by Summit/Cover-All.

As far as engineering, let me clear one thing up: Summit, as do all tension fabric structure manufacturers, supplies stamped drawings and calculations on all projects that require permitting. This is part of the standard package, and is usually supplied within 30 days of contracting. While the stamping engineer may not be an employee of the company, his/her work is covered in Summit's contract with the client and the liability for the accuracy of his/her work fall squarely upon the contracting party, in this case Summit.

Up to this point, 99% of all clients accepted the stamped drawings and calculations from the manufacturer without submitting them for independent review. As an independent consultant to this industry, I always advise my clients to review the engineering prior to contracting. Hopefully, in light of this incident, more will do so.
 
Entirely from left field, and you certainly don't have to give anything away, but how do you analyse these structures? Are there specific analysis packages, or do you use a general purpose FEA package? Or is membrane theory, and hand analysis, enough?



Cheers

Greg Locock

SIG:please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
 
I don't understand if the drawings were sealed.

Is it possible that Summit provided the building with the intent/agreement with the owner/contractor that the owner/contractor provide the engineering confirmation and seal?

Dik
 
I would think the analysis of the frames and trusses could be done by hand or by a general purpose FEA package.

The tension fabric follows the funicular curve of the loading, so it could be analyzed by hand as well. Any more accuracy than that is likely not warranted.

BA
 
Greg:

The bubbled dom is structurally similar to the shell of an airplane (3D), and with similar loading patterns (dynamic, vibratory, differential pressures). Only differ in materials and load intensity.
 
To clear things up and maybe better focus this thread:

This structure was not a bubbled dome. It had no curved surfaces. It had a 40' vertical sidewall and a pitched roof with an approximate 85' peak. The fabric is not a structural component and is rated only for things like tear strength, durability, and fire resistance. That is why the story circulating about the structure not being inspected after the fabric was replaced last year is something of a red herring- fabric issues should never cause a structure to collapse.

The frames are typically designed so that any cladding can be attached. A similar sized structure at Caesar's Palace (not a Summit) was completely reclad in sheet metal.

Analysis of the frames and trusses is generally done by hand.

I attached a photo of two structures at Texas A&M that are very similar in design to the Cowboys building.
 
 http://files.engineering.com/getfile.aspx?folder=ea201b72-7bf4-4dec-93a9-13a5181b9aab&file=DSCN9628.JPG
tentguy,

But isn't the fabric tensioned? That would create different loading conditions from metal cladding.

The Texas A&M facility is similar in cross-section to the one which failed in Philadelphia. They should be worried about snow/ice buildup in the valley area.
 
hokie66 - not much snow in Texas...especially College Station. They do get snow - but pretty rare.

 
Does anybody have the photo that shows how the original practice structure before collapse?
 
The Texas A&M structures are separate systems and are not connected in any way. The picture doesn't show it very well, but there is enough distance between the structures that snow would not build up on the roofs. The Philadelphia structure was a saddle truss, with the two arches sharing a leg down the centerline.

 
From the article nutte posted that I supposedly wrote... as if I can write... really nutte:

"If the stadium was designed to withstand winds in excess of 100 miles per hour, then its failure to do so suggests either faulty construction or faulty maintenance by the facility's operators, or both."

From the quote, the latter part is not necessarily a forgone conslusion as the author suggests. It's not just the strength of the wind, but how it is applied, not only in design, but also by nature. If this was an anomaly and highly inlikely to occur, then, like a 9 earthquake, are WE, as structural engineers, really ultimately responsible for the decision to ignore the possibility of occurrence of the anomaly? Or, is this, like the earthquake, merely an acceptible risk.

Any thoughts?




Mike McCann
MMC Engineering
 
"Irving police say their city suffered no other structural damage in Saturday's storm."

If it was an extreme event why wasn't there damage to other buildings?
Or is the argument based on a very localised extreme event, again?
 
"Up to this point, 99% of all clients accepted the stamped drawings and calculations from the manufacturer without submitting them for independent review. As an independent consultant to this industry, I always advise my clients to review the engineering prior to contracting. Hopefully, in light of this incident, more will do so."

I guess if I was having a building built, and a engineer stamped it, I would not want to pay to have it checked. Thats what I am paying them for, design, by a licensed engineer, and a building that works(ed).
 
Tentguy - thanks for the photo that makes more sense. A much more humdrum structure than I was expecting. However, the windloading on a leaky, flappy, old tent is far stranger than that on a normal building. Do the codes account for that?






Cheers

Greg Locock

SIG:please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
 
This is about as far from my area of expertise (if any) as I can get, but to address a point as brought up by apsix:

I had experience with a microburst striking an outdoor festival in my area a couple of years ago. The structures involved were just plain old tents. The microburst flattened two large tents (one a 100' by 180') but left standing small tents within 20 ft or less of them. Other weird things ocurred as well, such as a fireworks stand being rolled over.

Apparently a microburst can be very localized.

Regards,

Mike
 
A short update - apparently someone performed some structural upgrades to the structure some time ago. What struck me the most, however was the aerial photo - appears like a huge leeward suction to the left in the pic.

Dallas Cowboys Collapse
 
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