Metrodome Roof Collapses?

[Masherbrum]

Technology has changed dramatically in 27 years. 

[Strip]

For a dome it is...

Strip

[68ZooM]

I'm thinking that hey had some kind of heat failure that prevented the Roof from melting acumalated snow buildup, After doing some reading i found this to be interesting, could of been a system malfuntion
The roof

The Metrodome roof.The Metrodome's roof is made of two layers of Teflon coated fiberglass fabric, and is an air-supported structure supported by positive air pressure. It requires 250,000 ft³/min (120 m³/s) of air to keep it inflated. It is reputed to be the largest application of Teflon on Earth,   To maintain the differential air pressure, spectators usually enter and leave the seating and concourse areas through revolving doors, since the use of regular doors without an airlock would cause significant loss of air pressure. The double-walled construction allows warmed air to circulate beneath the top of the dome, melting accumulated snow.

 A sophisticated environmental control center in the lower part of the stadium is manned to monitor weather and make adjustments in air distribution to maintain the roof.

[Dichotomy]

So, somebody forgot to turn the thermostat up?

[68ZooM]

lol so you seen the keyword MANNED , after reading on that roof system it's a simple system really, I've seen similar designs on 1/2 acre sized greenhouses dual hvy gauge clear vinyl Air is used to inflate the roof and as the weather gets colder the heating fans kick in to keep the ice or snow off the greenhouse roof's ( metrodome is similar but on a much bigger scale) the key factor is the heated Air needed to remove and snow that builds up    i've designed enough homes and other buildings to know that snowloads are a very important factor in determing a roof system, pitch and materials to be used

[Babalonian]

Can you imagine had that happened during a game... anyone under that would have been toast.

Possible, but unlikely, mind you a very severe weather event was in mid occurance and I'd imagine it would of been a signifigant hinderance and deterant to anyone intending to get to anywhere in the area, nevermind to a stadium for a football game.  But that would be before taking into account the average darwin-IQ of your average NY Giants player and fan.

[Babalonian]

Engineering Fail.

General Uneducated Public-Perception Fail...

Kinda-sorta an engineering fail, but I'm thinking along the lines here of crusifying the Value Engineers (who are far more accountants than engineers) while everyone is thinking of throwing up the pencil-protector wearing professionals...  ...if the water and ice was comming up through the ground and into the stadium then it would be a civil engineering failure.  The client-representing but standards, safety and building code-complying structural engineers might be the ones to blame here for proposing an inadequate alternative to your standard solid roof, but I'm leaning twords pointing the finger at the over-ruling grand-pumba having-the-final-say client-representing value engineers who probabley won the day (and largest share of their client's attention), and all without any responcibility or liability.  Yup, I think I'm going to go with the value engineers winning that day here and the client/owner of the stadium being too fu!@ing cheap to pay for a traditional or more heartily constructed alternative.


 

[grizz441]

General Uneducated Public-Perception Fail...

Kinda-sorta an engineering fail, but I'm thinking along the lines here of crusifying the Value Engineers (who are far more accountants than engineers) while everyone is thinking of throwing up the pencil-protector wearing professionals...  ...if the water and ice was comming up through the ground and into the stadium then it would be a civil engineering failure.  The client-representing but standards, safety and building code-complying structural engineers might be the ones to blame here for proposing an inadequate alternative to your standard solid roof, but I'm leaning twords pointing the finger at the over-ruling grand-pumba having-the-final-say client-representing value engineers who probabley won the day (and largest share of their client's attention), and all without any responcibility or liability.  Yup, I think I'm going to go with the value engineers winning that day here and the client/owner of the stadium being too fu!@ing cheap to pay for a traditional or more heartily constructed alternative.

I'm thinking along the lines of engineering fail. 

[Babalonian]

That would be professional suicide for any structural engineer.  We don't know the factors that were involved but it will probably be released eventually and studied extensively.  Grizz is much more well informed on this area of expertise than I am so any speculation at this point is only that.  Speculation. 

They just showed it again at halftime and it looks to me like the fabric failed and caused a catastrophic failure across the boards.  What factors contributed to that are really difficult to ascertain at this point. 

But again that's just speculation.

The fabric failed because the dome collapsed.  The collapsing dome funneled all the snow, ice and water to the lowest point via gravity.  You'll note it did not signifigantly tear/rip/fail until it had collapsed and all the water on the dome was being forced down in a small and specific area of the entire dome.  The fabric is semi-permiable to allow the hot air and moisture generated off a large crowd of people to disipate through it.

My best bet/guess at the cause of this collapse is in the video footage from the inside, showing an empty and dark stadium with all the grounds workers inside wearing very heavy clothing (meaing it must of been pretty cold in there).  I think the stadium owner turned down the heat (or it was an unusally cold storm), either for some money saving or maintenance, and the fabric dome was designed to be heated, either independently or by the same air used to help push it up.  With the lack of heat source, ice and snow began to build up on the roof.  By the time the first indent was made and the first small leaks started (and water/snow/ice had nowhere to go) it was probabley too late to prevent it from snowballing.

[Dichotomy]

No disagreement here Babalonian and I'd have to agree on the surface with your assessment however as I'm not directly involved I've done as much research on the history of the stadium and the factors that have been released to the public as I can. 

Stuff like this interests me and I try to read the reports when they come out to further my very general knowledge of structural engineering. 

But it's nice to be able to bounce thoughts off of people who have similar interests and a more formalized education than I do.

Then I start learnin and stuff.  And I like learnin.

[Babalonian]

I'm thinking along the lines of engineering fail. 

I'm thinking since it was engineered to meet the requirements specificied and detailed by the paying owner or his design team, it's the owner's or designer's fault.  They should of specified a more expencive, durable and reliable alternative as I'm sure the structural engineers designed it to the specifications that they had to.

In a perfectly safe world the structural engineer has complete control and the final say in engineering X componenet on Y structure.  In a prefect world... they would be but this isn't a perfect world, and the designers, investors and value engineers have a lot more say in things than any of the real engineers.

OK folks, time to play the "Grizz knows everything" game here.  Lets say it is the fault of the structural engineers.  How is it their fault in this instance?  They might of not built the roof to the local and state building and safety codes and requirements, it might not of been able to handle the snow and ice.... oh wait, then how did they get issued a building permit by the local and state building and safety administrations?  Well they must of not had one... well, wait, no, this was not built before the late 1800s, so it's impossible for them to of built it without all the proper permits and waivers... well that's a possibility, it was awarded a waiver by the state and local agencies, so since the state and locals said it was OK and met the bill, it must be their fault!... well wait, that still makes it so the structural engineering guys aren't at fault and did what they were supposed to and payed to do.

[grizz441]

OK folks, time to play the "Grizz knows everything" game here.  Lets say it is the fault of the structural engineers.  How is it their fault in this instance?  They might of not built the roof to the local and state building and safety codes and requirements, it might not of been able to handle the snow and ice.... oh wait, then how did they get issued a building permit by the local and state building and safety administrations?  Well they must of not had one... well, wait, no, this was not built before the late 1800s, so it's impossible for them to of built it without all the proper permits and waivers... well that's a possibility, it was awarded a waiver by the state and local agencies, so since the state and locals said it was OK and met the bill, it must be their fault!... well wait, that still makes it so the structural engineering guys aren't at fault and did what they were supposed to and payed to do.

  

First of all, all I said was "engineering fail".  That is such a broad based comment I don't know why you are epically ranting over this.  I could have meant the engineering of the fabric, or the engineering of the heating system, or the engineering of the roof.  I honestly have not even looked into it at all other than this thread and the general news articles.  I'm sorry for inferring that the structural engineer might have been to blame.  Are you a structural engineer?  I'm not, but I will be in about 3 years after I graduate with my M.S. in Structural Engineering, and finish up my work requirements to get licensed in my state.  Anytime you want to talk loads, codes, dynamics, structural reliability, concrete design, steel design, masonry design, wood design, seismic design, etc.  Let me know. 

[Dichotomy]

I always want to talk that stuff

[Ghosth]

First off they never should have designed a fabric roof in Minnesota where it is possible to get 17" snow loads in a 24 hour period. So yes, design fail, huge design fail, but that 30 years late.

Second, while I have no proof, after the first dome collapse when it snowed they'd get people up there to get the snow off. With the dome about to be phased out I suspect someone was cutting back on the upkeep money being spent. With a normal snowfall you can probably cut 25 people back to 10 or so and still get the job done. How many where sent up to clear it compared to the past, well I have no way of getting that information. Also was there delay before the crews were sent up? Was someone sleeping at the switch? Slow to move or to spend money?

Seems pretty obvious that they came down because they could see that it was deflating and hence was going to fail. Once you  start deflating a fabric dome like that snow instead of blowing, sliding off will accumulate in the center accelerating the process of failure.

[Shuffler]

I'm thinking since it was engineered to meet the requirements specificied and detailed by the paying owner or his design team, it's the owner's or designer's fault.  They should of specified a more expencive, durable and reliable alternative as I'm sure the structural engineers designed it to the specifications that they had to.

Building code