Accident

[Grom]

Hello,

I found this accident on the other forum.
Here is link
Concert Cancelled After Accident | The Emory Wheel

[Grom]

I dont know how to edit, so I write another kessage.

I am not sure, but I think this is original roof

http://www.beezgetz.com/original_roof.jpg

(not for that event)

message to grom: in Dutch "Edit" means " wijzig" just push the button :-)

Ok, Thanks! I will remember that.

And the picture of this second roof is not the same roof. It seems smaller...

[Jeroen de Goei]

http://www.11alive.com/assetpool/images/07102518460_stage1025a%5B1%5D.jpg

een klein beetje betere foto.


verder is er weinig te zien.
te grote overspanning met te kleine truss en teveel gewicht.
Plat dak, misschien iets met wind.

[rinus bakker]

Luckily no-one was killed. But that is only going to be a matter of time.
The incident with 10 fatalities or more might finally wake us. And if not at another moment in time there will be 20 or more killed. And when this (yet another one, in the row of examples from the recent years) one doesn't help to get some common sense into manufacturer and user brains alike, that "Big One" certainly will happen at a random moment in time (choosen by Mr. Murphy).
And then we all will be in (big) trouble for at least a year or so, when H&S and Building Inspection Officials will raise 'their ugly heads' which up till now have been put in carefully planned "ostrich position".

As is usual in cases like this: the truss structure is failing. Right where it is expected to do so - at the central T-corner area.
It again makes you wonder about the very limited design (safety) factors as is generally used for truss - being part of a manual operated lifting structure. Rather than a fixed and steady building structure.

I have been propagating to limit truss loading to only 25% in situations like these: 50% because the roof is being left to rest on lifting machinery, and another 50% derating because of (generally 'turd'-designed [if designed at all]) X-, T-, or L-type of corner sections included in the structure.
Even with the limited capacties for those 'towers' they did not fail, and while looking at the picture there doesn't seem to be much load on these trusses.

On the other hand, who knows what kind of horribly sh*tty T-sections were used here in the first place.
Some manufacturers just don't have a clue on what they are welding together, don't do any design strength calculations, let alone know how end-users will be putting their products in action. And still sell a lot of their sh*t - because it is the cheapest in the market.

[CoenCo]

Hier wat extra foto's:

http://www.11alive.com/news/article_news.aspx?storyid=105391&provider=top

Dan zie je ineens dat het allemaal driehoektruss is, en dat er ook nog wat (vermoedelijk 6) wapperlampen op tegenlicht hangen.

Vervolgens lees je ergens: (quote LN)

Here's the sad truth about all this. This is the second time in as many years that this company has had a roof collapse. They're local here in Atlanta and they had a another roof come down a year or so ago at the annual Gay Pride Festival because of a "mirco-burst" according to the insurance type people. I had some friends working the salvage on that one. I'll have to make some calls and see what I can find out about this one.

En het enige waar de meesten hier op dit forum over zeuren is of er wel een safety aan je lamp zit

[Grom]

translator (http://dictionary.reference.com/translate/index.html):
furthermore is see little there.
too large overpressure with too small truss and too much weight.
Plat roof, perhaps something with wind.


translator:
Then to see you all of a sudden that the all driehoektruss are, and that there also still what (suspected 6) hangs wapperlampen on back-light.

Then read you somewhere: (quote LN)
.....
And some where the meesten nag about this on this forum is or there, however, the safety to your lamp sit
_____________________________________


Hello Jeroen, CoenCo, Rinus, and all other members!

I would be more than glad, If we could write in english this thread, so I could understand better. I am from sLOVEnia, and I can speak Slovenian, Serbo-Croatian, English and Dog-ish(dog language). Thanks to all!

The genies/lifts are still standing, some anchorage, so problem lies in truss failure. I have to agree (too), that does look like too large overpressure with too long and too small truss (triangular) and too much weight, perhaps wind.

And at the end, it does come to human error.

[showband]

When I notice the moving heads in the back of the rig, I cannot stop thinking they were very lucky that the breakingpoint was reached in passive setting. While building the thing.

If the truss had prooved just a tiny bit more solid, probably you would have overstressed the roof when these heavy MH´s would have moved synchonized. So slowly failing the truss DURING the show!

So just think how close they came...

[Funmaker]

Hier wat extra foto's:

http://www.11alive.com/news/article_news.aspx?storyid=105391&provider=top

Dan zie je ineens dat het allemaal driehoektruss is, en dat er ook nog wat (vermoedelijk 6) wapperlampen op tegenlicht hangen.

En het enige waar de meesten hier op dit forum over zeuren is of er wel een safety aan je lamp zit

he said:
Here are some extra Photo's [Link]
Then you will see that they used Triangel truss, en that there where also (about 6) Moving heads used as counter? light...

http://www.11alive.com/assetpool/ima...25a%5B1%5D.jpg

een klein beetje betere foto.


verder is er weinig te zien.
te grote overspanning met te kleine truss en teveel gewicht.
Plat dak, misschien iets met wind.

[link]
A little better photo.

there is a little we can see.
too big space with a small truss type and to much weight.
Flat roof, maybe something with the wind.


My own opinion: I follow Rinus and besides that I hope that they will learn there lesson before the worst happens on a big rig.
And after all the worst allready happened not in the Light and Sound world but also with a Rig in Germany they counter 5 deads, 1 missing and ceveral wounded people (can't find an english report on it)...

edit: the article: http://www.alertnet.org/thenews/newsdesk/L25844382.htm

[Gast1401081]

well, great..

just watched the new David Gilmour DVD, with a Making-of-movie, showing the Venice-st. Marcus-plaza stage almost coming down.
Build with heavy steel rental-layher, budget was appropiate, but still accidents happen.

Without everybody showing accidents due to gravity in this thread, there is allways a risk on collapsing, how safe you try to accomplish things anyway.

The problem is that becoming a taxi-driver takes you about half a year, getting all kinds of diploma's, but becoming a rental engineer is open to anyone...

on the subject shown : just a firm steel wire between the the both lower-ends of the roof might have saved the day...

[rinus bakker]

I do need a new set of glasses fur shure,
but anyone that can pinpoint me to (that part of) the picture
where I can see 6 Moving Heads suspended from this truss...
please help.
As far as I can see all that is shown is a couple of series of 8-bar (?) of PARs...
and a considerable amount of 'skin' on top of the truss - structure.
We are not here to figure out what these guys hould have been doing,
but what we ourselves should do before we put a kind of structure up like this.
It again get down to the sum of all suspended weight and the spans,
and choosing a decent (!) type of truss to support all this!

[Funmaker]

in the left corner you can see 3 Moving heads but i Can't find the other 3 so I assume the person who said so thought that a light tech always uses symetric light plans...
So maybe you should get a pair of glasses

[rinus bakker]

OK
Dat is dus onvermijdelijk:
Morgenochtend is de eerste handeling de gang naar de opticien.....
Maar nou even verder:
Jij herkent misschien die zenuwelampen ook nog wel kwa merk en type
(en gewicht???) ....
6 x 35kg ~ 210 kg UDL + 150 kg (zeil) = totaal 360 kg op ca. 12 m.
(Gokje voor het zeil = 2,5 kg/m2 op een opperlak van 12 x 10m)
Dat is 30kg / strekkende meter.....
Dat is voor de meeste lichte driehoekstruss wel een beetje veel.
En dan ook nog een (verzwakkend!) T-stuk in het midden!

Remark to Grom = Learn Dutch as quick as you can, because this is a nice forum!
In the mean time (translated):
OK -that's inevitable:
Tomorrow morning the first thing I will do is go to the .... (spectacle shop?) [.... shit ....] [I didn't figure my English was that bad].
But anyway:
If you know/recognise these 'nervouslights' maybe you also know what their weight is.
My guess would be:
6 x 35kg ~ 210 kg UDL + 150 kg (tarp) = total of 360 kg on app. 12 m of span.
(Guesstimate for the tarp = 2,5 kg/m2 on a 12 x 10m surface area.)
That would be 30kg / running meter.....
Which for most light duty triangle truss would be "a bit" too much.
And than we also find a (weakening!) T-section in the mid span!

In Dutch and English we all could understand a simple remark:
Another Amazing Triple-A rating in the Entertainment Business:
A bunch of Awesome Atlanta Assholes!

[Grom]

(how can I add a picture to a forum?)

I found only those (3) circled in red, green seems to be something, blue rectangle is empty. But not sure. link: http://www.beezgetz.com/mh01.jpg

edit: ok, I was too slow with picture, so I'll remove the link.
I like the site and I'm glad to be here, so I might learn Dutch. (Wijzig means edit, right?)
Thanks to all!

[Highfield]

yes but most lightingplans are symmetrical, so there will most likely be another set on the opposite side. by the way: do not forget the set of par-like fixture's at the fronttruss, hartingmultis weigh a lot too..

[RenéE]

To me, the bad design of this construction seems like a much bigger factor in this accident than just the truss itself.

I mean, maybe they could have prevent this accident by using other trussing and putting in a lot sturdier corner but is taking the bending stresses on the corner away (for example, by the suggestion that ******** did or by putting in a horizontal truss) not a much easier/better option?
(sure, it will look a (little) bit less clean...but if that's the issue, why didn't they also use a lot better looking truss towers instead of these lifts?)