Temporary Stage Collapse at Indiana State Fair
Temporary Stage Collapse at Indiana State Fair
(OP)
http://ww w.cnn.com/ video/#/vi deo/us/201 1/08/14/ha ll.in.stat e.fair.sta ge.collaps e.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??
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??






RE: Temporary Stage Collapse at Indiana State Fair
BA
RE: Temporary Stage Collapse at Indiana State Fair
http
RE: Temporary Stage Collapse at Indiana State Fair
"Accordingly, engineers are designing temporary structures that are strong enough to survive a once-a-century hurricane when in fact they will be used for only a short period - sometimes just a day or two - and would never be used to shelter people during a strong storm. The most these structures are likely to face is a thunderstorm, but the building codes call for designing for hurricanes, which drives up costs unnecessarily without increasing safety."
I disagree, and agree with BA.
These stages for mass popular events have the same useage as a stadium and the same consequences of failure, so they should be designed to the same standards as a permanent stadium. The fact that they are moved around between uses is surely grounds for additional caution, not reduced loading.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
There is an interesting 2008 article on the US standards for wind loads on temporary structures at http://l
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
For short term duration wind loads, a smaller (statistically speaking) wind load might apply. However, ASCE 37 uses a time duration of the structure to determine the wind load reduction from the standard 90 mph.
For the case of a traveling stage rigging, what is the time duration? I wouldn't necessarily say it was just the 3 days or 1 week that the concert was occurring. But as it moves around the country, it is constantly exposed to the wind and perhaps has the same statistical exposure as a 10 month structure, or a permanent one.
RE: Temporary Stage Collapse at Indiana State Fair
In that statement is the problem. Different juristictions, different requirements, BUT FOR THE SAME STRUCTURE. This is not a normal situation necessitating professional consultation, not some backyard podunk musician's trainee.
I apologize for my french...
Mike McCann
MMC Engineering
RE: Temporary Stage Collapse at Indiana State Fair
As a side note, from a public safety point of view, I would agree with BA, Ron and others and advocate that temporary systems should be designed for the same magnitude of loads as buildings. Although many temporary structure designs have the disclaimer that they must be taken down before adverse weather conditions occur, many irresponsible contractors disregard the advice. Therefore, the structures are still subjected to the same loading risk/probability at any instance of time and should be designed as such (without regard to how long the structure is used).
Structural Design Engineer
New York, NY
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
Certainly some simple importance factor changing how to could signify a safer design through other rules. But for temporary what we see are waivers, exceptions, more than anything. Philosophically, it looks as if construction wants to retain not only gains from risky business, but a reputation of still being so through lamentable particular cases like the one causing these comments.
RE: Temporary Stage Collapse at Indiana State Fair
Tower cranes are temporary structures with regulations that require putting them into free slew under strong winds. And it seems practical and enforceable.
Perhaps stronger regulations should be decided for temporary structures which involve the presence of the general public, and even stronger regulations if this general public is a crowd with hundreds of people of more.
Mr Gorlin's comparison with umbrellas or even market tents in http
It seems impossible to have one single regulation that would encompass all temporary structures.
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
In the document it stipulates a minimumn wind speed for which a temporary structure should be designed based upon it's location, time of year it will be in place and length of time it will be in place.
A management regieme was to be in place with Anemometers measuring wind speeds (gusts not average). At certain wind speeds ie. 60% and 80% of max design wind speed (whether this is as specified above or the maximum the weakest member can accept) the following would be carried out.
At 60% staff whould be put on alert that action may be required.
At 80% with an increasing trend, cladding would be removed and the site would be secured against access by the public within specified zones (ie areas around the structure into which it may collapse).
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
Sometimes we play the odds...and don't win.
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
Even a reduction from 90mph to 70mph would result in only 60% of the pressure and huge cost savings.
Hurricanes dont form in minutes, there are usually quite a few hours of warning for which the site can be evacuated.
I think that there is definately a case for nationalised standards that can be waved in front of the local official.
RE: Temporary Stage Collapse at Indiana State Fair
If it was correctly assembled (a big if), I suspect that the forensic study will show it was safely designed for some wind of a magnitude of 45 mph.
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Temporary Stage Collapse at Indiana State Fair
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.
RE: Temporary Stage Collapse at Indiana State Fair
- 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.
RE: Temporary Stage Collapse at Indiana State Fair
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?
RE: Temporary Stage Collapse at Indiana State Fair
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?
RE: Temporary Stage Collapse at Indiana State Fair
Mike McCann
MMC Engineering
RE: Temporary Stage Collapse at Indiana State Fair
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
RE: Temporary Stage Collapse at Indiana State Fair
Mike Halloran
Pembroke Pines, FL, USA
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
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.
h
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Temporary Stage Collapse at Indiana State Fair
OSHA's fine was settled for $1700 per dead man.
No wonder things don't change.
Mike Halloran
Pembroke Pines, FL, USA
RE: Temporary Stage Collapse at Indiana State Fair
http://www
One of the photos clearly shows what a sudden "brittle" failure this was. Seems to me that some ductility would have helped a lot.
RE: Temporary Stage Collapse at Indiana State Fair
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
RE: Temporary Stage Collapse at Indiana State Fair
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".
RE: Temporary Stage Collapse at Indiana State Fair
If these structures had properly sized deadmen, they wouldn't have dead men.
Mike McCann
MMC Engineering
RE: Temporary Stage Collapse at Indiana State Fair
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
RE: Temporary Stage Collapse at Indiana State Fair
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
RE: Temporary Stage Collapse at Indiana State Fair
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.
RE: Temporary Stage Collapse at Indiana State Fair
h
BA
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
RE: Temporary Stage Collapse at Indiana State Fair
I am thinking that this is not a design issue but a construction issue, just from looking at some of the pictures. But thats my WAG
RE: Temporary Stage Collapse at Indiana State Fair
Sounds like a scary design concept.
RE: Temporary Stage Collapse at Indiana State Fair
This is actually a quite common design philosophy on temporary fabric structures.
RE: Temporary Stage Collapse at Indiana State Fair
Mike Halloran
Pembroke Pines, FL, USA
RE: Temporary Stage Collapse at Indiana State Fair
1) How do you design something, especially a fabric, to fail at a certain load? It seems easy, but in practice, it's pretty hard.
2) It would be tempting to the staff to say, "...hey that tarp keep blowing off its mounting. People are getting rained on. Someone go up there and wire it up better."
RE: Temporary Stage Collapse at Indiana State Fair
Regards,
Mike
RE: Temporary Stage Collapse at Indiana State Fair
I think these structures should be designed for the standard code level loads. Nobody has a good handle on the probabilities and life safety risk, therefore any loading reductions are merely a guess.
This is a code issue, and the good ol boy engineering mentality came back to bite Indiana on this one.