Temporary Stage Collapse at Indiana State Fair 1

[Forensic74]

http://www.cnn.com/video/#/video/us/2011/08/14/hall.in.state.fair.stage.collapse.cnn?iref=allsearch

In the wake of the stage collapse at the indiana state fair, what are the design requirements on this type of structure? Are they even inspected??

 

[charliealphabravo]

I'm just arm-chairing it from a grainy video of course but it doesn't look to me like the stage was constructed with an expectation of lateral load.

 

[ztengguy]

Im not sure, but in another post there were some details of the structure, and how if its to be used outside, guy wires need to be installed. Were there guy wires installed? I hope not for the engineers insurance policy sake.

 

[paddingtongreen]

The wind front was five or ten miles ahead of the storm. The rain front, in falling, drives a column of air down on the ground where it spreads out sideways as a big wind front along the ground. People were mapping the the storm on radar, but that shows the rain, not the wind. They were waiting for the thunder storm to to get close before evacuating.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[Marksen]

Tower cranes are allowed to freely slew whenever unattended. An entirely different thing than dismantling a structure or parts thereof with limited time after a severe storm warning is issued.

When a tower crane is in operation while the wind speed is low, followed by a rise of wind speed, the crane's anemometer rings an alarms which tells the crane operator that he must cease working: unload the load, rewind the hook and the trolley, put the crane in free slew mode and climb down. I guess it takes a few minutes to do all this. And we don't hear about wind-related tower crane accidents so often.

If you have a team trained for this, it doesn't need to take much time to lower the roof. These stages are similar with sailing ships. You need a crew to promptly reduce sails when the storm is coming.

You could also have a regulation to lower the roof of a temporary stage whenever unattended.

 

[JLNJ]

More armchair quarterbacking follows:

- It didn't look to me like the structure had much in the way of lateral stability.

- I'm with Jed in that for it to fail at 60 mph then it had a real "design" capacity of 40 mph or less. This is unacceptable to me.

- The reality is that the people what erect things like this play the odds and almost never get caught. (See the collapse of the Dallas Cowboy practice facility.)

- It takes a large mistake to overcome all the load factors and all the material safety factors to actually produce a failure.

- Tower cranes, by and large, are run by trained professionals. I'm not sure the same can be said about fair staging and rigging.

 

[hokie66]

I wouldn't argue too much about the appropriate wind speed for design of these things. Maybe it can be less than for permanent structures. Whatever wind speed is selected, I would bet the bar that in this case, something was omitted from the construction.

To rely on removing cladding or lowering a roof as a thunderstorm approaches seems ridiculous to me. Anemometer or not, weather prediction is just not that good. Who is going to be the rigger risking his own life and limb to save the structure?

 

[JAE]

You wonder about the loss of knowledge that occurs over time with structures like these. The original designer/manufacturer perhaps had a checklist and user-manual on how to erect and maintain the temp. structure as well as a wind capacity/warning aspect.

As the temp structure is used over time, personnel change, the manual is lost, the structure is sold to someone else who doesn't get or doesn't read the manual, etc. At the end of the day did the individuals who erected the structure have the knoweldge and authority to close down the program when the weather kicked up....or was anyone even thinking about the danger?

 

[msquared48]

Exactly my point JAE...

Mike McCann
MMC Engineering

 

[csd72]

I agree that the structure should have been capable of withstanding more than it has, I just disagree with the gut reaction of some that it should be designed for the same as a building.

Some structures would be impossible to build if they had to withstand the full wind load at every instant during construction. There has to be some rationality.

There are no 100% guarantees only statistic improbabilities of failure. There is nothing to stop two 1 in 1000 year events happening in the one week, its just very(to the power of fifty)unlikely

 

[MikeHalloran]

Construction of the subject structure was alleged to be complete.


Mike Halloran
Pembroke Pines, FL, USA

 

[ztengguy]

perhaps a PE should be hired to inspect, and bless it once erected. At least then it would have some professional who looks at it, not just the county fair chairman walking by it chewing his hot dog.

 

[paddingtongreen]

@csd72, Obviously it would be impossible to provide full wind stability during construction, but I disagree on the the design of the finished structure. I believe they should be more stringent because of the material losses from wear and tear due to the constant construct/tear-down sequences, and the loss of original knowledge/memories. I also suspect that their risk of design wind is higher per day of use, the normal building stands 365 days per year, these structures for much less, but mostly in the high risk season.

The Willow Island Cooling Tower Disaster is a good example of lost knowledge/memory. Research-Cottrell used a jump form system where the scaffolding, forming and "cranes" for pulling buckets of concrete up a sloped wire from ground. The system had been used many times, worn HS bolts had been replaced with black bolts, They were moving the forms up before the concrete was sufficiently set, and they were running the bucket up at much higher than design speeds leading to much bigger impacts. When the system collapsed, fifty one men died.

Wiki's report is a pretty good condensation of the official one.

http://en.wikipedia.org/wiki/Willow_Island_disaster

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[MikeHalloran]

Re Willow Island,
OSHA's fine was settled for $1700 per dead man.
No wonder things don't change.


Mike Halloran
Pembroke Pines, FL, USA

 

[graybeach]

Some interesting photos and info here:

http://www.jimonlight.com/2011/08/15/indiana-state-fair-stage-collapse-five-dead-now-what/

One of the photos clearly shows what a sudden "brittle" failure this was. Seems to me that some ductility would have helped a lot.

 

[SnTMan]

I am not trying to pass myself as a structural engineer, nor do I have any detailed knowledege as to the what happened in Indiana. I have been involved in outdoor events on a volunteer basis for about 20 years and offer some of what I have learned from this. Take it for what it's worth.

For the most part, the people who set up, babysit and tear down the stages and so forth consider what they do to be as important as what you and I do, are generally very safety-oriented and consider themselves as much a professional as you or I.

The equipment is generally shop-built and of good quality, although I don't know what standards it may be designed and built to. Perforce, portability and ease of set-up / teardown are major condsiderations in the design of the equipment.

Jurisdictional issues have been mentioned by several, and I can tell you that it gets more difficult with each passing year to throw an outdoor festival, what with the Fire Marshall, Health Department, and who knows what all enforcing their piecemeal regulations. In my area, the authorities generally try to enforce, to the extent they can, building codes for temporary event structures such as tents. As an example, several years ago we had to start placing lighted exit signs in each tent. Adding another layer of inspection such as a PE would no doubt help, but no guarantees, after all permanent, Code designed structures fail due to weather and other causes with some regularity.

Deciding whether to evacute an event due to weather or other reasons is not easy. There is a non-negligable possibility of causing harm during an uneeded evacuation that has to be weighed against the potential harm from not evacuating. Remember, we are talking about the general public here. This is completely aside from the business considerations. Due to the legal climate the risk of getting it wrong either way is not attractive.

A few years ago, an event I was involved with had what was generally considered, by the people running the event and making the decisions, a fast moving but not particularily severe thunderstorm collapse directly above the event grounds, creating a microburst. Some severe damage and injury did occur. This in spite of opinions of local weather people and so forth, who the organizers were in communication with, that this storm was not especially threatening. The risks of evacuating were judged PRIOR TO, and rightly I believe, to be worse than the risks of staying put.

It can be a risky business, you do the best you can.

Regards,

Mike

 

[bigmig]

Coming from someone who had dug a lot of ditches I can tell you that the speed and choas with which these events occur will never tolerate a team of white collar inspectors signing off on every nut and bolt. This is a traveling circus. The establishment of more rules and "safety" nets to prevent accidents like this will only lead to more "corner cutting" by those who are told "get that damn thing up right now or find a new job".

I know that will make some blood boil on this site in the name of life safety, but I'm just telling you how it is in the field boys. If I haven't had a job for 6 months and I have 3 kids to feed, I will choose job over the 5% chance of that thing falling down any day of the week.

And finally, why leave the decision to call the event up to a person, who the last time I checked is persuaded by a million things. I simple device that measures wind speed, connected to an alarm, that could be only heard by even planners, so as to not cause chaos, would indicate guess what fellas....get everyone out the shows is over. That way when everyone comes crying about how much $ they lost etc., all the event officials do is point to the machine and say, "This is why the show was called".

 

[msquared48]

Mike H:

If these structures had properly sized deadmen, they wouldn't have dead men.

Mike McCann
MMC Engineering

 

[dik]

From the Toronto Globe and Mail, "Indiana's decision to essentially police itself as it investigates a fatal stage collapse at the state fair is raising questions about how objective the probe will be.

Workplace safety agencies, state police and fair officials are looking into Saturday's collapse that killed five people and injured dozens. But the lone outside agency brought in so far is an engineering firm hired by the Indiana State Fair Commission.
More related to this story

At least three killed as storm wreaks havoc at Belgian music festival
Five killed, dozens injured by stage collapse at Indiana State Fair
How the Ottawa Bluesfest stage came down – and why it could happen again

Kentucky attorney Jerry Miniard, who represents an injured girl, says the state is essentially investigating itself.

An expert says that could be a conflict of interest. Judy Nadler of the Markkula Center for Applied Ethics at Santa Clara University says it might be better to appoint a regulator from another state to investigate."

Dik

 

[SnTMan]

msquared48, at one of the events I worked, years ago, they had the stage top tied to several Jersey barrricades, don't know for sure, but probbly one at each corner. You'd think that would be deadman enough.

A gust lifted one of the barricades enough for it to come back down on a guy's shoe, fortunately just missing his foot.

Regards,

Mike

 

[hokie66]

SnTMan, sorry, but you just don't know how ridiculous that sounds.

The whole emphasis with these things, including the ones which have collapsed, seems to be support of the lighting and sound equipment. Not much thought to lateral stability or uplift. The typical guywire anchorage details shown by the outfit which designed the Indiana structure showed the type of screw in anchors used to stop house trailers from blowing away.