hangar collapse

Never time to do it right, but always find time to do it over.

I posted about this on a flying forum, it being a hangar, and have gotten a few comments by Boise area pilots saying it was "super windy" that day. A sdeep a chord as those huge beams had, that's alot of wind push.

Really bad people had to die and get injured because they couldn't wait for a calmer day.

Besides the usual rules of thumb that I was taught such as:
~ first completing all the columns including girts and especially flange braces
~ portal frames (if any) installed too
~ choosing the first and second main frame to place from a braced bay

.... has anyone experience with the use of a "temporary support tower" added to provide support at the peak of the main frame - to so to speak 'three point support' the main frame rafters until the metal building system is completed?

The company involved is large, Big D is the name. I see them over here on this side of the State and they operate in other states as well. They had numerous OSHA violations in the past years. This was posted on local news apps here. Most it appears to have been tie off violations. They brought in inspectors from all over to investigate this. I know some of the first responders that responded. A lot of great work done in the response to this, that kept the death rate lower than it could have been.

KSSS said:

The company involved is large, Big D is the name. I see them over here on this side of the State and they operate in other states as well. They had numerous OSHA violations in the past years. This was posted on local news apps here. Most it appears to have been tie off violations. They brought in inspectors from all over to investigate this. I know some of the first responders that responded. A lot of great work done in the response to this, that kept the death rate lower than it could have been.

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In the past years....sounds like a beancounter is now driving the ship there eh ?

digger doug said:

In the past years....sounds like a beancounter is now driving the ship there eh ?

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One of the founders of the company Craig Durant, (Big D steel) was one of the guys killed. I find that rarely are the beancounters the ones driving for speed in assembly. Typically beancounters have no push on a ironworking crew.


There's no "assembly manual" on buildings this size. There's "industry knowledge" and "best practices" ways to go about building them. There's no engineered wind load factors on the building, as its partially assembled. IT is engineered to withstand wind loads and calculations for such, once its all bolted together and has the steel screwed down.

Hindsight is 20/20. I've bolted things up, and seen them wiggle waggle, and decided more bracing was in order. Sometimes you just roll with it, and every purlin you put in, stiffens it all up. These guys got bit by high winds at the wrong stage of assembly.

oceanobob said:

has anyone experience with the use of a "temporary support tower" added to provide support at the peak of the main frame - to so to speak 'three point support' the main frame rafters until the metal building system is completed?

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You could do something like that, its how they used to build old railroad bridges and such- build a falsework, assemble the bridge on it, and then pull the falsework out. I've never seen it done on a red iron building. Occasionally for some goofy overhanging cantilevered structures- a falsework might help. I've only used cable bracing on a building like they were building this hangar.

I've seen cables to deadmen made of a cluster of 4000# ecology blocks. It was not this large a building though.

Don't they have to calculate wind load at different wind speeds as part of the reaction process? I remember on the Big Blue collapse the wind load load was huge. I don't know if it's a requirement or not but seems it should be.

I saw some pics with just a few anchor bolts and the bottom plate torn off the upright. Others with no anchor bolts showing. With drill in anchors there isn't the immediate anchoring available with pour in studs.

*
The very first image is of the Hanger--Skywest Hanger-listed as a currant on going job.

Welder Dave said:

Don't they have to calculate wind load at different wind speeds as part of the reaction process? I remember on the Big Blue collapse the wind load load was huge. I don't know if it's a requirement or not but seems it should be.

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Going to run full calculations of every possible rafter wind load resistance, at every possible wind speed.

And do that calculation at every stage of construction, because the building gets stronger with every piece of steel added. And it also catches more wind every time a piece goes in.

And then they will run calculations with every possible angle that the wind can come from, because it makes a huge difference if the wind is 90 degrees to the rafters vs. with the rafter sections.

Never going to happen. Its madness to think it would.

You'd think they would at least have an idea of wind loads at the max. wind speed they would do the lift. I know lifts have been postponed due to too high of winds. I don't know if wind speed is the only variable though. Do they consider the capacity of the crane and if the lift is close to that or how far the boom is extended?

Today I just learned the MBMA and the MBCEA "coordinated" a book called Temporary Bracing Guidelines thru the MBI, a non profit formed in 2000. The TofC and the first chapter can be previewed. About $300 or less if one is member of MBCEA....
Printed only and I have yet to learn the number of pages.

There's a YouTube video - at Metalcon where the book is introduced in March 2022.
At around the 38 min mark there are recommendations for features that are to be added to the base building in order to help with the construction loads: things like bigger anchor bolts, thicker baseplate, eave strut flange bracing, more purlin to flange bracing in the Braced Bays etc etc As I read the power point bullets I wondered why no one mentioned that stuff to me when I order these bldgs - but now I will be more informed.

Of course they had an idea of the wind load. Same seat of the pants we all use. Sometimes it doesn't work out. I've lost one set of trusses in my career. Happened at night and nobody was hurt. Freak windstorm with 60+ mph winds. Didn't just pull all the braces on the gable, it snapped 2x4s and 2x6s in half. I didn't feel too bad about it since most of the trees around the house had blown over too

Latest reports say that they were setting an end truss. Could be possible that there was bracing in place but had to be removed to install the last truss. That's complete speculation on my part. I don't know how they do things in steel. In wood frame construction we almost always start at the gables and move inward

I think the size and weight being lifted and potential for disaster needs to be considered. I think wanting to get done faster certainly could have contributed.

Welder Dave said:

I think the size and weight being lifted and potential for disaster needs to be considered. I think wanting to get done faster certainly could have contributed.

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Of course it was considered! There was an error in the considerations.

Complacency easily sets in with both scenarios of experience, and inexperience. With having fatalities involved this will be drawn out for years and long after the job is reconstructed and finished up.

I've only done one project like this and it was my own. I had no experience then using equipment the safety police would openly ridicule but I wasn't trusting anyone else's judgement, only my own. I didn't want the structure collapsing and well know the winds endured here so I thought braced until firm before moving on. I erected all the columns and girts prior to setting the first roof beam, then the first span, braced it to the ground diagonally with the screw anchors, then the second span bridging the two spans together with purlins. Then moving to the next span and repeating till complete. I had all the purlins bolted before moving to the next starting from the center out towards the end walls.

I didn't know that one of the founders was killed. That wasn't in the article I read. I guess that speaks to how critical this project was.