Collapsing rig - scary pictures

[lightjocky]

http://www.averagewhiteband.com/cgi-bin/ib...t=758;top

 

check out this link showing a stage that collapsed !!!!

 

lightjocky

 

 

Moderation: Lightjockey - I have approved this post but changed the title of the thread as there's nothing funny about a drummer nearly being killed.

[adamharman]

Anybody heard what happened there?

 

It doesn't look like it was very heavily loaded, maybe a dozen macs and a hundred parcans. I wouldn't want to lift it all, but considering the roof should be designed to take some load plus wind loading and it doesn't seem to have been very windy, it should take that.

 

It all looks to have failed at joints rather than buckling, maybe somebody put it together with the wrong grade / size / quantity of bolts?

[Jivemaster]

Thankfully no reports of injuries, but I still wouldnt want to be explaining that to HSE, or the insurers. It's a pity there seems to be little or no feedback from incident investigators to the industry.

[tokm]

Scary stuff indeed...

 

One other thing about the pictures concerns me, other than all the mangled truss... Is it just me or in all/nearly all the pictures, there's people on stage after the accident..

 

1st picture down under the title > 'Here's a few more photos:' concerns me most.. :blink:

 

I'd not go near that in a million years, who knows how unstage the rest is! Or is it just me? :o

 

Tom

[Cougar]

Very scary, and no you wouldn't get me that close till there was conformation that the rest was safe and secure and even then with caution (although in fairness we don't know how long after it collapsed those photos were taken they may have had it checked).

[broadcast_techie]

Ok, I'm no expert, infact I have very little knowledge of truss weight limits....

 

From what I can see on the pictures there's nothing that heavy in the rig, just a number of parcans and less than a dozen movers, yet the poster comments suggest that the rig was too heavy for the truss.

 

Kris

[tom_the_LD]

That is very scary! Do you think all the truss was checked prior to being put in the rig? If it had a dent and/or crack that wasn't noticed, could this weaken the truss enough for something like this to happen?

[tokm]

although in fairness we don't know how long after it collapsed those photos were taken they may have had it checked

A valid point.. though it looks roughly the same time of day.. i.e. pretty soon after the accident.

 

And yes, it is a shame we don't get reports from accidents more often, other than what we hear through the grape vine. Oh well.

 

yet the poster comments suggest that the rig was too heavy for the truss.

They all sound like general non-technical people TBH. Its the bands forum, not some US entertainment industry forum, so I'd take any comments on there with a pinch of salt. I've heard similar comments before, oh that looks too heavy.. etc etc, even when I'm using 1 tonne slings on 100kg loads, off large I beam, its all about peoples perceptions.

 

Do you think all the truss was checked prior to being put in the rig? If it had a dent and/or crack that wasn't noticed, could this weaken the truss enough for something like this to happen?

Look at the pictures, the roofs fallen inwards! The only reason the truss has 'caved' in is because the points the truss were on had 'dissapeared'. Or is there a chance that the reason the roof fell in is because some part of the truss failed, causing one point to take more weight (more than should have been on it) and thus making the truss cave in?

 

And yes the roof doesn't look the strongest, but I'm with Kris, that rig can't weight that much, so chances are it's a fault with the stage. But, I suppose, we'll never really know..

 

Tom

[Cougar]

I agree it looks soon after, but I think they probably have enough to worry about on the health and safety side. So I thought it only fair to at least give them the benefit of the doubt.

 

Having looked at the photo's a bit closer it looks like the entire rig was suspended from the roofing structure (zoom into the first photo left hand side) rather than being supported in its own right, I don't know enough to comment on the roof structure but I would not be surprised if it was only designed for the weight of the roof not to be loaded in its own right, it also looks like a fairly big span.

[Jivemaster]

....snip....yet the poster comments suggest that the rig was too heavy for the truss.

 

Kris

 

 

The picture proves that the truss in its condition, in the local weather conditions, wasn't strong enough to carry the attatched load safely

 

Whether the truss, its condition, the weather, the loading or something else was at fault will likely be determined by investigators. Til then this is a timely reminder to use trussing within it's limits and permissions.

[adamharman]

The picture proves that the truss in its condition, in the local weather conditions, wasn't strong enough to carry the attatched load safely

 

The truss as it was rigged wasn't strong enough to carry the load safely.

 

I'm no expert on that particular type of structure, but I do have a BSc in civil engineering, so I have some experience in structural design. The overall proportions of the thing don't look unreasonable at first glance. I certainly wouldn't have worried about being under it.

 

It was persumably designed as a temporary stage roof, so should have had some capacity for lighting to be hung from it, and there isn't really that much load there. I have no knowledge of US design codes, but the sort of wind loadings we'd have to design for in the UK would amount to way more than that, and the weather was good.

 

There isn't any mangled truss there, it all seems to have failed at joints. Difficult to tell from lo-res photos, but I can't even see any distortion on the ends where it failed. I don't think anybody would be stupid enough to fabricate something like that without having an engineer design it, so I see the main possibilities as the design engineer screwed up badly on the joint design, or the riggers cut some corners with the bolts or whatever held it together.

[Andrew C]

Speculative thoughts:-

 

1) The roof looks a bit lightweight to me. Not much tube to the m3. May well be designed properly, but just looks sparse...

 

2) It is on a beach. Beaches are windy places, with on-shore wind through the day, and off-shore after dark (typically).

 

3) There are two layers of cloth. Could these have funnelled the air causing air pressure gradients that had not been designed for?

 

It would be a good thing if we heard more about what really went wrong in this sort of incident; maybe it would help to prevent the next one.

[Dmills]

And yes, it is a shame we don't get reports from accidents more often, other than what we hear through the grape vine. Oh well.

 

The maritime industry handles this much better, in that the MAIB write very good investigative reports on accidents which are deliberately written not to be usable in court. They do however make recommendations for other skippers of similar vessels.

They make fascinating reading and are really very useful as a means to drive people to think. Would that the HSE published something similar for land based accidents.

 

For this to work however these investigations have to be done by a body quite separate from any organisation responsible for prosecution, people will talk (By and large frankly) to the MAIB about what went wrong, I don't think I know anyone who actually likes talking to the HSE inspectors under any conditions....

 

I think the air accident people have a similar scheme.

 

Part of it I think comes down to those industries recognising that having one of your ships mentioned in a MAIB report is not the end of the world and is in fact preferable to not having the information that that body produces, would say a staging manufacturer feel the same way?

 

Regards, Dan.

[Simon Lewis]

All,

 

Take a look at the ProSoundWeb forum, where this was first posted. The link to AWB's webpage is there, together with some local news pages and the production company that put up the stage.

 

Two things to note...

 

Some interesting photos on the production company's page

 

The gig went ahead after they removed the broken truss!!

 

The discussion varies in quality, but there's pretty much the same reaction that we have shown.

 

 

 

Simon

[Pete McCrea]

From what I can see it appears to be a curved roof structure that is flown of 6 points (3 either side of stage), with the lighting trusses dead hung from the roof structure. It looks like the front span of truss failed around the connection detail near the mid point of the span. Whether that was the first point of failure, or due to previous failures I couldn't say.

 

It does strike me that the sections used in the fabrication of the main roof trusses seem awfully small. The connection or joint between the elements that make the main truss seem to have parted company relatively easily.

 

What also concerns me is the lean that has been put into the downstage Right PA towers by the movement of the roofing system. And the fact that people are continuing to use the stage despite what I would see as the structure now being outside the original design parameters.....