Denny's Sign Failure 8

[dik]

https://www.ctvnews.ca/world/toweri...gh-wind-killing-1-injuring-2-others-1.6239328

Was it removed before an investigation... seems a little hasty.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Alistair_Heaton]

The foundation gets put in when they do the foundation for the building and presumably gets left for a month to cure. But again it will be a standard one for range of heights in the area. There 10's if not hundreds on the same design in the state possibly small, medium or large height profiles. I very much doubt an engineer has looked at that individual sign post. There maybe even a standard foundation for them locally that has been used since the 60's and its used for all of them. Unless someone says hang on the soil type is going to be an issue here then nobody will look at it.

Same with the signage attachment its the way its always been done. Unless the regs change they will continue to do it the same way however glaringly obvious it is that its dodgy. To change regs would mean all the others are unsafe and require modification.

It seem there isn't a high failure rate. Presume they fail in extreme adverse weather but deemed understandable.

I suspect my barn has had way more man hours and thought put in it than most franchise buildings. The ones I see going in round me are all manufactured in Poland and arrive with the kitchen fitted if fast food. A local team does the foundations and car park. And a Polish team turns up to connect the modules together.

As I said I am just cynical on cost saving prowess of large franchise groups. These days they will just drop it in with autocad, 5 seconds zero thought.

 

[SwinnyGG]

The number of man hours invested has no relationship at all to the quality of the delivered engineering.

You should generally just stop commenting on construction related topics.

I respect you, you're a 'known' member of this forum, but in this case you have no idea what you're talking about.

 

[Alistair_Heaton]

My point is there is no likely engineering been done on a standard sign in a franchise restaurant. There maybe differences state to state depending on local codes. But there will be hundreds of the things that a structural Engineer will never look at.

Does every standard freeway gantry/lights in the USA go past a structural engineer? Because the certainly don't in the UK and Europe.

 

[spsalso]

"My point is there is no likely engineering been done on a standard sign in a franchise restaurant."

I am pretty sure the drawings for that sign had an engineer's stamp on them when they were submitted.

If they did not, and they were accepted, and there was a failure in the design, there will be some very sad people after the trial.



spsalso

 

[SuperSalad]

I serve on my very small town's Land Use Board. No sign could be legally installed without a PE stamp on the designs.

I can't say every municipality is the same, but there is absolutely engineering required for something like this in my own town.

I suppose it could be pencil-whipped and get through, but I assume the level of liability involved would prevent that from happening.

- Andrew

 

[LittleInch]

That type of pole design appears to be very common in that location so seems to be a repeat order. Some are two segment, others three or four

You do wonder though if that mid point sign which is at 90 degrees to the main sign but lower down affected the frequency of any vibrations. No other really tall sign in that area seems to have one. They have been there since at least 2008 though - earliest street view image. GE images are not clear but it doesn't look like it was there in 2004.

But four relatively weedy looking bolts to hold that size sign looks very non redundant. The little snap of a security video in one of those news reports seems to show a pretty sudden failure with no real wobbling beforehand. It just fell off.

Quite odd really that more haven't fallen down.

But we're running here with no drawings, no decent pictures or any installation documentation. So running blind. We don't even know if the sign was bolted on first and then the pole jacked up or the whole thing laid on the ground and lifted up in one lift or ???



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[EdStainless]

To be honest, if a sign failure does not result in a death the chances of us hearing about it are near zero.
Care to estimate how many signs like this there are in the US?
I would wager that a few of them come down each year but don't crush a car full of people.
Likely a line of research for the lawyers, 'the owner should have been aware'.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Brian Malone]

EdStainless - good point on the level of public awareness rises if bodily injury or death occurs with a sign collapse. I did a very low-level internet search on road sign collapse/fail and not much comes up other than actual freeway signs and a few assorted storefront type signs. The closest I found to the Denny's sign is this sign topple in Arizona - but it is different since the complete sign support fell over:

https://www.abc15.com/news/region-n...ort-mohave-arizona-crushing-vehicle?_amp=true

 

[Alistair_Heaton]

Thats what my feeling is LittleInch.

Is one supplier, one design signed off by a PE which is used by everyone in the area with little control on what's stuck on the top of it or method of attachment. If they are allowed max 100ft tall and the sections would take that to 110ft they cut off the top section to size and then weld a plate onto it and put the sign on. The bottom foundation mount plate will be welded on in a fab shop. The top section I have a feeling is not and is in the hands of the install crew.

 

[spsalso]

Allistair,

Each location has individual submittals for building permits. I expect you could submit a "mass produced" version. But it would have to have that stamp and be approved individually for each location by the "locals". There is NOT mass-approval crossing jurisdictions.


spsalso

 

[Alistair_Heaton]

That's not the way it works over here. As long as its a certified product and your inside its design spec then it will be dropped in the design by an architect and then reference the product certification. Nobody will touch it afterwards.

The first time I heard of it was when I was asked by a civil about an ANSYS buckling model he wanted to do as he wasn't happy how something looked but in theory it was none of his business because it was a certified product (hint the reason why I mentioned standard freeway gantry/lights) I don't know what the outcome was but he was right it didn't look very healthy.

To be fair I think in the 90's they changed this marketing signs alleviation in the UK that if it was outside a certain distance away from the building and/or not below its roof line then it had to be looked at more closely and documented. Which is maybe the reason why we don't have signage like you do up to the heavens. And even then they have to have a zone rating on them. In zone 5 they pretty much all have to have a full environmental survey and load case done on them. Which is why you don't even get price boards in petrol stations in Shetland but they get 100mph+ winds every winter at some point.

Anyone got access to the permit office in that area to see what they actually have on these signs? That's the only way we will find out,

 

[phamENG]

I worked for one of the largest sign companies in the US for a while shortly after I graduated (managed sign packages for new stadiums, managed a lot of major brand names, etc.). We rarely touched these big ones - outside of the company's core business - but the process was similar. One engineer would design the sign head, I would design from the head to the foundation, and then the design would go to the factory for fabrication layout and out to an outside PE for verification and certification (usually a calc package and a letter, though some jurisdictions required drawings from the consultant as well). This was for each installation.

Mass approvals here are for components or minor systems. A window or garage door, some special wall panel systems - but the overall structure still has to be reviewed and approved, and the foundation and lateral force resisting system is always subject to review. (Quality of the review varies by jurisdiction, though...)

Some smaller monument signs were accepted without PE sign off, but they were always small and low to the ground, and light enough that a grown man could probably catch it if it were toppling over on him.

 

[SwinnyGG]

That's not the way it works over here.

Again, I'm trying to be nice.. but this didn't happen 'over there'. It happened here.

Does every standard freeway gantry/lights in the USA go past a structural engineer?

Generally, yes - and I very much doubt that they are being installed anywhere in western Europe without any review at all, either.

 

[Alistair_Heaton]

They don't, they go passed the civil and that's mainly for the crash stuff around them and he would check the foundation mount the quantity surveyor had allocated. This for a free mount. If there is a bridge or something else involved near by its different.

It should be easy enough for one of you guys to pull a few of the permits around that one and see what's in them and who installed them. Are they a separate permit or part of the building permit.

Plus if its so old maybe they have changed the head on it since the initial install.

 

[SwinnyGG]

They don't, they go passed the civil and that's mainly for the crash stuff around them and he would check the foundation mount the quantity surveyor had allocated. This for a free mount. If there is a bridge or something else involved near by its different.

You know this how?

The project I just finished had a 7' tall monument sign, which required a stamped, engineered foundation for me to pull the permit. For a plastic box with some LED strips inside that weighs about 50 lbs and is mounted directly to the ground.

 

[phamENG]

It should be easy enough for one of you guys to pull a few of the permits

Not so much. An issue came up on a project that I had designed, and I wanted to know exactly what had gone to the City for approval. They acknowledged that my drawings were part of the permit review, but they would not release anything to me without written approval of the property owner and permit holder. The level to which they do or not do this varies by jurisdiction, of which there are thousands in the US.

A freedom of information act request might get it (don't know - never tried one). Most of the permit documents I can get are mined from poorly secured, internet connected databases that Google manages to mine for me...

 

[spsalso]

"It should be easy enough for one of you guys to pull a few of the permits around that one and see what's in them and who installed them. Are they a separate permit or part of the building permit."

It might be, but I'm 2337 miles (3761 kilometers) away, and it's inconvenient. And even then, it might take an hour or two to get results. And it might take more than one visit. Have you ever dealt with bureaucracy?

Building permits are public records, and are available for all to see.

Yup.
As we say in the States. That's the theory, anyway. It is indeed amazing how many public documents are not viewable by the public.

I expect that these building permits have not been digitized, and probably never will be. So on-line access is out. One has to present oneself and make the request. More likely than not (in my opinion), the clerk will make an effort to find the item. "An effort" does not translate to "here it is". I have, in fact, run into some VERY helpful clerks in this area. And some decidedly NOT.

Someone physically closer may take up your suggestion.

I think it might be fun!


spsalso

 

[dold]

A freedom of information act request might get it (don't know - never tried one).

I've done dozens of these to get existing drawings for buildings. Pretty easy, just fill out a FOIA request form and describe what you're looking for. It's hit or miss depending on the jurisdiction and the 'type' of building. Obviously they're not going to give you access to drawings for Area-51, but usually they'll cough up documents for an old K-mart. IF they have the documents you have requested then they are required to provide them to you in some manner but occasionally you'll run into stuff like pham mentioned - you have to get permission from the owner of the building and/or the architect/engineer/etc.

 

[LittleInch]

A second person has now died

https://www.wsaz.com/2023/01/23/second-person-dies-after-dennys-sign-falls-car-kentucky/

Some interesting video on that link.

The hole sizes in the top plate of the pole which is shown do look rather different than on the sign. And no sign of any distress on the bottom of the bolt holes.

So a bit like spalso said - wrong size bolts. It's far from unfeasible that they just added or used a set of oversize washers which essentially made the washer the structural element. Or the holes were deliberately bigger to allow for any misalignment.

It's been seen on pipe flanges which is one reason some oil companies banned the use of washers on flanged joints after someone did the same thing and eventually the washer failed and the nut just pulled through the hole.

I don't have a lot of faith anyone will ever find out though. - "An investigation is ongoing by the Elizabethtown Police Department as well as the City of Elizabethtown’s Planning Department.".

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[dold]

A couple more closeups. Still not great photos but it does kindof look like the bolt heads (bolts seem to have been installed with the bolt head below and the double nuts and a washer on top) slowly broached their way through the holes in the plate on the pole. I think I can barely make out that there are 3 bolts still remaining in the plate on the sign (pics 2 and 3). It doesn't look like there was a washer between the bolt head and the bottom of the pole top plate (pic 2). It looks like the pole plate is maybe 3/4" thick? Sign plate is way thicker for some reason, maybe 1-1/2" to 2"? It could be that the actual sign "cabinet" is a "off the shelf, worst-case wind speed" item that was designed once, but I'm sure the pole was actually engineered for the site . Also, the HSS member going from the sign plate into the cabinet looks beefy as all hell too. Furthering the "design it once" theory for the cabinet. Maybe the cabinet manufacturer "designed" the plate and HSS using the "I have no idea what I'm doing but when in doubt, make it stout" method. And clearly had no clue about edge distances. I'm positive that the actual foundation and pole would be required to have stamped design/drawings for every site, but now I'm curious about if the cabinet itself would be considered part of the 'structure' or more of 'equipment' that just gets mounted to the top (in the eyes of the jurisdictions).
I suppose over time the cyclic loading (100's of cycles per day? More?) just let the bolt head chew/broach its way through the pole plate. Surely the bolts were installed tight but over time 'something' happened and they loosened or stretched which allowed the sign to start 'wobbling' and initiate the broaching. I'd assume the plates would be A36 steel. The edge distance on the sign plate is obviously way too slim (can't be much more than 3/8" of material left between the hole and the edge) but it doesn't seem like that was a factor in the broaching of the lower plate.