Comment: State Fair Stage Collapse.

[unclesyd]

I've been following the news concerning the stage collapse at the Indiana State Fair as close as possible from afar. One possible smoking gun as appears in some photos, that is what appears to be billboard/sign atop the stage roof line. It appears to be a an add on as it's braced in one direction with wood braces, not the lattice work used for the stage. Rough scaling puts the sign height at about 4' and as long as the roof line. The sign was advertising the band that was going to appear. As the stage collapsed in what I call a matchbox type failure this sign was acting like a giant sail and the problem was it appears that the wind direction that caused the collapse was perpendicular to it at the time. I think the sign contribute to the collapse due to the moment put on the lattice framework of the structure. This added force would be very bad as the frame has very little if any diagonal bracing.
It will be interesting to see the results of the investigation as based on statements given by various officials there is a lot of CMA going on.

 

[VEBill]

On 18 July this year, the stage at the Ottawa [Canada] Bluesfest collapsed due to a "freak" wind gust. Luckily it collapsed away from the crowd and nobody was killed.

There seems to be a lack of common sense about the implementation of such structures. Wind? Outside? Imagine that.

 

[Demon3]

If there's one thing I know about common sense it's that it's no so common

Chris DeArmitt PhD FRSC CChem

 

[MintJulep]

The process seems to be a bit laissez-faire in Indiana.

http://www.indystar.com/article/20110816/NEWS15/108160318/Inspections-not-required-outdoor-stages

A couple flat beds full of scaffolding parts and a crew of riggers.

 

[unclesyd]

Here is one picture showing the sign discussed in my OP.

http://businessjournalism.org/2011/...ollapse-checking-up-on-amusement-park-safety/

 

[MintJulep]

Video:

http://newsfeed.time.com/2011/08/14...e-fair-killing-at-least-4/?xid=rss-topstories

The sign seems to be braced with the same scaffolding that the rest of the thing was made from.

The "roof" seemed to have no lateral support at all. Just columns at each corner. No diagonals. No guy wires apparent.

Basically a bad "design".

 

[zdas04]

Don't need no stinking engineers at band concerts (or bonfires). That structure doesn't look like it a had a chance in gusty winds from any direction. It looked better from the front and back than from the sides, but any significant wind load was going to take it down.

David

 

[waross]

And another:
Nashville Business Journal
Date: Tuesday, August 16, 2011, 6:55am CDT - Last Modified: Tuesday, August 16, 2011, 7:29am CDT

Although not as deadly as the fatal stage collapse last weekend during a Sugarland concert at the Indiana State Fair, a similar incident in Alberta, Canada, two years ago has led to several charges against three companies, including Nashville-based Premier Global Production Company Inc.

Premier Global and two other companies — 1073732 Alberta Ltd. and Panhandle Productions Ltd. — each face charges under Canada's Occupational Health and Safety Act.

The charges follow a local investigation into the August 2009 incident at the Big Valley Jamboree when the main stage collapsed during a wind storm. Dozens of workers were injured and one spectator died.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BigInch]

The sign was just the straw that broke the camel's back.
"the frame has very little if any diagonal bracing."
That's the real problem. Latices are just a column built from individual members and the column can fail globally when they sidesway, even without having a local member yield until well after the colapse was initiated.

We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer

 

[IRstuff]

There's a thread about the collapse in the SE forum:
thread507-304796

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[TheTick]

Not long ago, a student cameraman died in a lift collapse while filming Notre Dame football team's practice. (Note to foreigners: ND also in Indiana.)

 

[francesca]

I only lived in Indianapolis for 14 months, but 60-70 mph winds weren't exactly a regular occurrence, if they occurred at all while I lived there. I'm not sure the stage was designed for that kind of wind, and I imagine it must have been swaying a fair bit before it keeled over. I guess that's what you get for ignoring a warning to take shelter in a covered area.

 

[IRstuff]

The SE forum thread discusses that very subject, i.e., that since such stages often roam the country, they need to be designed and inspected for pretty high winds.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[hokie66]

There is another thread in the Structural forum.
thread507-304714

In that thread, member Marksen listed the following link to the design engineer's catalogue, and pointed out that guys are required if used "outside". Wonder if the guys were there, and if so, if the anchors were good enough.

http://www.jthomaseng.com/pdffiles/!JTE Brochure 2006.zip

 

[patprimmer]

Maybe the guys where to interested in the gals. ;-)

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[unclesyd]

Just a note:

Along the Gulf Coast from Mobile, Al to Panama City, Fl during the summer there are usually 10 to 20 of the type lattice work temporary stages similar to the one that collapsed. I went and looked at two on a local beach and could see no guys or bracing against wind forces. One of these stages uses a trussed design roof that appears to be used to support a heavier load, lights and speakers while the smaller stage has a flat sloped roof. The vertical supports appear to be the same design on both stages,probably to allow modular construction. Both of the observed stages face the Gulf of Mexico which could expose them to some very strong straight line winds that accompany line squalls coming in from the Gulf.
As I understand it no local jurisdiction has any input in the use of such stages and depend solely on the production companies word as to use.

 

[SomptingGuy]

Just a thought from a non-civil.

Do temporary structures need to comply with the same building codes as permanent structures? If not, who is responsible when people get injured? When does temporary become permanent anyway?

- Steve

 

[IRstuff]

Steve, the other threads already discuss this specific subject. And while not SE or CE, I agree that their requirements need to as stringent as most permanent structures, particularly because the assembly/reassembly cycle cannot ensure that each time the structure is put up that it's operating at its design strength and stiffness.

It would seem plausible that the local authorities ought to inspect such structures prior to public use.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[BigInch]

Temporary becomes permanent when it kills somebody.

We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer

 

[VEBill]

Again - this time in Belgium.

http://www.bbc.co.uk/news/world-europe-14582448