Collapsed Pole Style Shelter - Negligible Lateral Support
- Thread starter lakeroadster
- Start date
driftpin
Well-known member
Wow, it just 'racked' to one side, and the minimal connections failed. Not much to transfer the load from the wall or roof to the foundation.
It might not be as-pretty, but those sonotube concrete pours should go up to the roof beams, and strapping over the tops of the beams fastened with long screws into the sonotubes. They could always 'case' the concrete columns in wood for appearance's sake.
There better be a forensic engineering inspection & report on any other shelters built at the same time.
It might not be as-pretty, but those sonotube concrete pours should go up to the roof beams, and strapping over the tops of the beams fastened with long screws into the sonotubes. They could always 'case' the concrete columns in wood for appearance's sake.
There better be a forensic engineering inspection & report on any other shelters built at the same time.
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readhead
Well-known member
Poorly conceived and executed.
jives
Well-known member
Every new pole barn question should be first directed to this thread. Not that I'm anti pole barn (I've got one and would build another), but as a DIY project it is easy to overlook (or not know) about pin joints, lateral bracing, diaphrams, and so forth.
readhead
Well-known member
I'm not sure it is fair to compare the two. A pole building would have some shear built into the walls. It appears that there were no real connections to overcome the moments at either the top or bottom of the posts.
Specked by a Civil Servant with job security
Designed by the low bidder
Built by the low bidder
Approved by a well educated & credentialed Government employee.
I have no idea why it failed.
Any chance the roof can be flipped and hauled out with a quad, lot of usable material there.
Designed by the low bidder
Built by the low bidder
Approved by a well educated & credentialed Government employee.
I have no idea why it failed.
Any chance the roof can be flipped and hauled out with a quad, lot of usable material there.
driftpin
Well-known member
That looks like something someone said, "hey, I can build a shelter roof!", and then did it. I don't know of any structural plans examiner I've ever worked with who would have approved that.
Approved by a well educated & credentialed Government employee.
Local jurisdictions have no oversight in federal land. Try to get that design past your local building department and it never would have been approved.
Approved by a well educated & credentialed Government employee.
Local jurisdictions have no oversight in federal land. Try to get that design past your local building department and it never would have been approved.
ford33
Well-known member
Federal projects require architects and engineers. Usually they do excellent work. Looks like somebody did not do excellent work on this one.
US Fish and Wildlife Service- Ranger Sally filling in for Superintendent Biff while Biff is honeymooning with his beloved Lance.
Standard shelter plan number 34860z
Constructed by Metuu minority contractor qualified employees between yoga and Zimba sessions.
Damn nice steel roofing. Probably salvageable.
Standard shelter plan number 34860z
Constructed by Metuu minority contractor qualified employees between yoga and Zimba sessions.
Damn nice steel roofing. Probably salvageable.
ptgarcia
Well-known member
I wouldn't place blame without looking at plans, first. It could have been a bad decision by the contractor to make a design change because he could do it cheaper and put more money in his pocket. I've seen that happen plenty of times.
billgreenwood
Well-known member
I would have to agree with this. The wall girts and metal siding give a full pole building much more strength than this pavilion had.
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There will be no finger pointing and everyone will get a raise and a promotion!!!
Just because 'Ol Joe has a contractor's license does not mean he has a clue as to what he is doing. If that was the design on paper then 'Ol Joe didn't even know enough to ask a question.
The up-side is that no one was hurt.
Just because 'Ol Joe has a contractor's license does not mean he has a clue as to what he is doing. If that was the design on paper then 'Ol Joe didn't even know enough to ask a question.
The up-side is that no one was hurt.
oldmxracer
Well-known member
Was a damn nice looking shelter before it went down !
Think Your close up pictures show why it failed.
Thanks for sharing !
Think Your close up pictures show why it failed.
Thanks for sharing !
matt_i
Well-known member
Good post, Lakeroadster. Illustrates the effects of overlooking moment-connections perfectly.
Too bad on the building/shelter. You'd think the Park Service would have the basic skeleton design of these figured out since about the 1920s...then people could do all they wanted in beautifying the basic structure.
Too bad on the building/shelter. You'd think the Park Service would have the basic skeleton design of these figured out since about the 1920s...then people could do all they wanted in beautifying the basic structure.
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bczygan
Well-known member
No triangulation in that column base plate and the diagonal braces are basically decorative.
Bill
Bill
MushCreek
Well-known member
The diagonal braces are too small, and poorly fastened. Whoever built it probably over-torqued them and stripped the wood as well. Once the diagonals failed, the bases didn't stand a chance. Longer nails would have helped, but only slightly. When I built my raised deck, everything structural is through-bolted. I don't trust lags.
red61cj5
Well-known member
This is not a pole barn, pole barns have walls. The killer here was the wide open spaces between posts. Even a metal walled pole barn would have had 2x4 diagonals between posts. This is an example of aesthetics overcoming common sense. Those home depot deck brackets didn't help either. Nice trim though, I like the way even the battens on the gable are beveled at the bottom. Maybe he was a trim carpenter, not a framer.
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jives
Well-known member
Correct. But my point was that even a rudimentary building -- pole barn or pavilion -- needs proper engineering. A brief look at questions on GJ about pole barn framing shows a lot more questions about pole barn specs than about stick framing. Lateral braces, Y-braces, through-bolts vs. nailing girders, notched posts for girders, pole spacing, post-to-concrete brackets, hole backfill material, and so forth are all question posted recently in GJ regarding pole barns.
My Old Tools
Well-known member
So they built a fake timber frame structure. The real thing would have been mortise and tenon at the joints and the braces. Then the failure point would have moved to the post connection. There isn't enough there to prevent uplift in a stiff wind. That big open roof area is a wing and will generate considerable lift in a strong wind. This is how timber framers build them. 1/4" steel plates are lag bolted into the bottom of the posts and are then welded to the steel posts. The steel posts are later covered with rock.
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rburke65
Well-known member
Hard to believe that that connection was approved by some one and that no one questioned this. Well....maybe they did question it. As said, job security.
OP
lakeroadster
Well-known member
Not Fake "Timber Frame", Poorly Implemented "Post and Beam"
No, actually they built a fake "Post and Beam" structure. A poorly implemented version.
Post and beam uses steel plates to tie members together.
Timber Frame, as you stated, uses mortise and tenon joints, secured together with oak pegs.
If they would have simply used structural brackets at the lateral support attachments, similar to those shown below, using through bolts, and also through bolted the columns to the headers, the building would not have racked over.
For all we know the design specified this, yet the builder decided to go the easier cheaaper route. But as I originally stated:
No, actually they built a fake "Post and Beam" structure. A poorly implemented version.
Post and beam uses steel plates to tie members together.
Timber Frame, as you stated, uses mortise and tenon joints, secured together with oak pegs.
If they would have simply used structural brackets at the lateral support attachments, similar to those shown below, using through bolts, and also through bolted the columns to the headers, the building would not have racked over.
For all we know the design specified this, yet the builder decided to go the easier cheaaper route. But as I originally stated:
aka Larry
Well-known member
So they built a fake timber frame structure. The real thing would have been mortise and tenon at the joints and the braces. Then the failure point would have moved to the post connection. There isn't enough there to prevent uplift in a stiff wind. That big open roof area is a wing and will generate considerable lift in a strong wind. This is how timber framers build them. 1/4" steel plates are lag bolted into the bottom of the posts and are then welded to the steel posts. The steel posts are later covered with rock.
Damn, were they planning to park a semi on the roof of that shelter?
pancho400cid
Well-known member
Very Educational discussion. Thanks for posting.
rlitman
Well-known member
The one holding up the remains of the roof? Yeah, good catch!
No, a 747. LOL
teamextreme
Well-known member
One thing to note, while everybody is playing monday morning quarterback and concluding everyone in the government is an idiot and that's what caused the failure, it is probably important to note that we had some helacious winds lately, with gusts topping over 100mph in some places around the state. In fact, the highest gusts ever recorded were pretty close to where lakeroadster is. If a hurricane rolls through Florida, nobody is surprised when buildings are ripped apart, I would guess there were some hurricane force winds at play here.
On the subject of poorly engineered construction, however, it's a bit concerning to see the pic of the post base and the comments that it would never pass inspection. I recently built a pole style lean-to addition and the building dept insisted on use of nearly identical post bases. I did use those Simpson screws instead of nails, hopefully that helps? Mine is walled in and sheeted, so I'm not too concerned, but my building dept spec'd pretty much those exact bases, albiet for a much smaller structure (12x30).
On the subject of poorly engineered construction, however, it's a bit concerning to see the pic of the post base and the comments that it would never pass inspection. I recently built a pole style lean-to addition and the building dept insisted on use of nearly identical post bases. I did use those Simpson screws instead of nails, hopefully that helps? Mine is walled in and sheeted, so I'm not too concerned, but my building dept spec'd pretty much those exact bases, albiet for a much smaller structure (12x30).
Radix2
Well-known member
In my experience the last thing that inspections will catch is structural deficiencies - especially that type that require reading the directions for specialty connectors, plates, straps, fasteners. The inspectors don't read em, the framers don't read em.
It has a hole, stick something in there...
It has a hole, stick something in there...
OP
lakeroadster
Well-known member
Good point. It has been crazy windy.
However where the building is located, it is surrounded by miles of dense pine forest... and the trees tower above the shelter. We didn't see a single tree that had been recently knocked down by winds anywhere in the vicinity of the collapsed shelter.
Here's a photo:
As for what should be used for attachment of the poles to the floor the bracket needs to attach to the column with through bolts, not nails, not lag screws. And those through bolts need to be away from the end of the column.
Something like these.
I doubt that there was excessive wind speeds at play here, I don't see any trees in the photo that were blown down. The fact that there are lots of trees around it also help block the wind force on the building. The concrete brackets IMHO are totally useless for uplift protection. You need something with substantial through bolts and not sheet metal and roofing nails. As to how it got built this way, maybe somebody took their standard walled pavilian plans and just decided that they could simply make it open by not installing the walls. Not knowing that the walls are structural preventing the building from racking. Also without walls, wind is allowed to blow under the roof causing significant uplift. I'm surprised it didn't blow over during construction.
Brian
Brian
bczygan
Well-known member
It was a building shaped object...
Brian_WK
Well-known member
Good point. It has been crazy windy.
However where the building is located, it is surrounded by miles of dense pine forest... and the trees tower above the shelter. We didn't see a single tree that had been recently knocked down by winds anywhere in the vicinity of the collapsed shelter.
Here's a photo:
As for what should be used for attachment of the poles to the floor the bracket needs to attach to the column with through bolts, not nails, not lag screws. And those through bolts need to be away from the end of the column.
Something like these.
Off topic but what are these brackets called?
Thanks
Brian
OP
lakeroadster
Well-known member
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btdobie
Well-known member
teamextreme
Well-known member
With no trees down and surrounded by trees, I guess so much for my wind theory. I wanted to use the post brackets in the upper right picture lakeroadster posted, the imbedded in concrete style. My building dept wouldn't let me and said I had to use the style that bolt to the concrete with a single anchor bolt in the center and are only a couple inches high onto the post. Also couldn't use thru bolts, had to use nails or screws like I did. Very strange considering everyone here is very critical of this style of support, for apparently good reason.
Orionrising
Well-known member
could have been uneven loading of the roof due to snow and wind.... and it sure looks like those posts were attached with roofing nails?
lieutenant
Well-known member
OP, good evidence photos and explanation of went wrong, thanks for posting.
Radix2
Well-known member
Those are the short "joist hanger nails" that idiot framers use everywhere... even though there are only specific places that they should be used.
Then idiot building inspectors demand they be used do they can see the little circled number in the heads...even in double shear joist hangers.
Get the bench builder to build the next shelter
This local example looks a little better to me. It has a steeper pitched roof so how will it react to wind in comparison?
2 times as expensive?