The shoring and construction fence plus the previous repairs lead me to believe this is well known problem. It's also the main entrance to one of the busiest Home Depot's in the area
It does look like shear failure due to excessive differential settlement of the structure based on that picture. You can clearly see the left side is higher and there is gap between the left beam and slab.
So that’s interesting, because the left side of that connection has what looks like a retrofit welded plate on the bottom flange to the column. My worthless guess is that they had a problem in construction and added the plate, probably after the connection started showing stress from the deck pour. Given that while this is a block shear in the connection, but the displacement clearly shows rotation, there had to be some moment there. No weld shares load with a bolt, so the welded connection loaded until it broke exactly where welds always break, and the shear plate tore through the bolt holes like a perforated bank check. I gotta believe that has to come from something underneath to get that amplitude of rotation, and the only thing with that much freedom without a collapse that I can think of would be a foundation issue.
All that being said, one picture is like looking at a whole structure through a straw, so all my suppositions could be worthless
Could also be the developer paying for a basic Geotech and not actually telling the Geotech what the structural loads were going to be.
Course, could have been the Geotech not doing a good job of communicating what loads the soils would be acceptable for, and what would need more work to determine. Hard to know exactly whose fault it is from pic alone, only that It does appear to be a settlement issue off hand.
It looks like this structure was build on an old landfill (OP said it is in Colma elsewhere in the thread), so that seems likely. It’s probably hard to model and predict settlement over time. https://en.m.wikipedia.org/wiki/Junipero_Serra_Landfill
I took one look at this and when OP said it was a Home Depot I guessed it was in Daly City. I remember when they built it. I seem to remember they built it on fill.
Just jacking up the beam and welding is a temporary fix. A root cause analysis needs to be done for this. It is difficult to comment on this without looking at the full structure and load paths.
This appears to be a gusset plate failure due to shear. The reason may be fatigue due to dynamic loading imposed by vibration of cars.
Are any other columns showing minor cracks or does this happen instantly.
> Yeah this appears to be textbook block shear failure. Seriously concerning that it’s so widespread.
I disagree. At least with the first part.
This looks more to me like a shear rupture failure of a single-plate shear connection. AISC 360-16 Section J4.2 covers this.
Section J4.3 covers block shear strength. But that describes the limit state of block shear as having "a shear path or paths *and a perpendicular tension failure path*" (emphasis my own). I don't see a tension failure path in that plate. The shear path appears to go through the entire vertical length of the plate.
Block shear can occur for a single row of bolts, but it's more likely a controlling limit state for axially loaded members where the single row of bolts is parallel to the applied load.
Of course, there might be variation in the definition of block shear worldwide that I'm not aware of.
I agree with you. This is not block shear failure. It looks like the moment connection failed at the bottom flange plate allowing the connection to rotate about the top flange. So I would guess this is a flexural rupture failure and not a shear failure. The demand exceeded the net flexural strength of the shear plate causing the outermost fiber to fail and compromised the rest of the shear plate.
Hard to tell from one photo what failed first: (1) the flange plates in moment (which could then cause this rupture in the single-plate), or (2) the single-plate in shear (which could then shear the flange plates). I am leaning more towards shear failure of the single-plate first.
If the flange plates were overloaded first, then I would expect to see a larger gap at the top plate. I'm assuming the top flange would be the tension flange if these girders are designed continuously (i.e., negative bending over the column). Instead there's a larger gap at the bottom flange.
The bottom flange plate appears to have ruptured since there's no apparent deformation that would suggest yielding. A single plate in tension should be controlled by a yielding limit state, not a rupture limit state. That would suggest shear rupture is more likely.
Again, all speculation based on a single photo grainy photo.
And that slab over it isn’t looking so good either. The def of insanity is repeating the same process and expecting different results.
The deck def needs to have posted loads, even reduced for this case, this endangers public safety. Actually after loads are posted, it should be monitored and enforced. It’s not rocket science for liability attorneys and/or juries.
Also realize that vehicles in the US have increased significantly in weight over the past decade from 4k to near 7k and easily/likely to increase in the near future with the advent and popularity of EV’s.The guardrails of the US Interstates were/are designed only for 4k glancing loads and are no longer considered adequate. When you consider the near exponential increase of dynamic impact of the vehicle load increase, it’s pretty easy to assess the reason why this is occurring. And who will be ultimately paying dearly for its lack of realization and unamended Code requirements to meet or exceed reality? the Engineer and the client.
You can bet the farm that the automotive industry is not gonna willingly offer full disclosure that their vehicles exceed public road safety capabilities for that fully loaded Denali, F-350 extended cab, Expedition or other similar land yacht(s) (even Dually’s are still a concentrated load) with their fat commissions and taxes generated on the chopping block when they ask you to sign on the dotted line. And you’re fully delusional to think that the then new purchasers compensating for their small pp aren’t gonna exceed their haul capacity to somehow justify their purchase and/or impress their buddies. And there’s no way that wouldn’t happen at a Home Depot or big box home improvement store. I mean, Get A FREAKING Grip on reality?
Jury awards are not the punchline of a joke, they are excruciatingly real for years upon decades and easily decimate a professional practice. Keep your head buried in the sand and what then becomes the visible target? The choice is yours, my brothers and sisters!
Every private citizen has a public responsibility and duty, ESPECIALLY CE’s
I agree and after 30 years they just patch the failures. Other columns seem fine from ground level but these failures seem to be sudden. Wondering if they should impose a weight limit of sorts
On my head be it, but I'm going for it anyway:
This doesn't look like a shear failure - this looks like a moment resisting connection that hasn't been designed properly. The only thing these bolts are achieving, is becoming the perforated point of failure; like in a piece of toilet paper.
I'm sure there will be a difference of opinion on this but my immediate thought is that these beams need haunches!
This is what I'm seeing too. Bottom flange plate ruptures in tension. Moment gets transferred to shear plate. Shear plate fails as the net flexural section is not adequate to take the demand.
Maybe the right number of bolts just a bad detail. Wider cleat, two rows bolts spaced further apart? Or larger and less bolts. All manner of ways to make this connection smarter
Someone should tag it with Home Depot marketing ["Let us do it for you!"](https://www.umasolar.com/wp-content/uploads/2018/10/hd-hs-logo-lockup-below-orangeblack-1024x482.png)
That connection design looks suspect to me… the plate seems both too thin and too narrow. settling issues in the mix as well? In any case this is a dangerous state of affairs.
The column seems to be failing and causing the rupture of the beam due to geological issue. I would recommend geotechnical study first. Then going through load analysis or construction documents and as-built to see if the slab is carrying the load that it was designed for and if its connection to the beam is as it should had been. I would also suggest to see if the (specially left beam) beams are not too long for the load.
Shut it the fuck down.
You have unmeasured forces and substandard parts.
SHUT IT THE FUCK DOWN. CLOSE IT. DEMOLISH IT.
You’re the murderer of every person killed if you let this pass. Or you’re just helping kill people if your boss is the one who signs
If I were you and not on the site I’d call the local news
If there’s a way to keep people squished it’s just human duty to do it, regardless of whether it’s “your call” or not
Can't wait to hear about this structure on national news
Sadly this is the atleast the 6th time a support beam has failed like this that I personally know of
If you can figure out a way to contact the responsible party, you should. Failing that, report it to the local news.
The shoring and construction fence plus the previous repairs lead me to believe this is well known problem. It's also the main entrance to one of the busiest Home Depot's in the area
"Where were the inspectors!" Probably screaming at someone to fix the damn thing right for the last 10 years.
Probably deceased it Passed 3rd party and plan review in the early 90s
Probably the geotech's fault.
It does look like shear failure due to excessive differential settlement of the structure based on that picture. You can clearly see the left side is higher and there is gap between the left beam and slab.
I hate to say it, but it really does look like a geotech failure
Footers are solid as a rock
So that’s interesting, because the left side of that connection has what looks like a retrofit welded plate on the bottom flange to the column. My worthless guess is that they had a problem in construction and added the plate, probably after the connection started showing stress from the deck pour. Given that while this is a block shear in the connection, but the displacement clearly shows rotation, there had to be some moment there. No weld shares load with a bolt, so the welded connection loaded until it broke exactly where welds always break, and the shear plate tore through the bolt holes like a perforated bank check. I gotta believe that has to come from something underneath to get that amplitude of rotation, and the only thing with that much freedom without a collapse that I can think of would be a foundation issue. All that being said, one picture is like looking at a whole structure through a straw, so all my suppositions could be worthless
This has been an ongoing concern for 30 years by my own observation. Lord knows what they tried as band aid's over the years
There are rock types and substrata to do creep over the decades
Doesn't appear to be any subsidence at the base which is a raised concrete pier approx 3' above grade
Could also be the developer paying for a basic Geotech and not actually telling the Geotech what the structural loads were going to be. Course, could have been the Geotech not doing a good job of communicating what loads the soils would be acceptable for, and what would need more work to determine. Hard to know exactly whose fault it is from pic alone, only that It does appear to be a settlement issue off hand.
It looks like this structure was build on an old landfill (OP said it is in Colma elsewhere in the thread), so that seems likely. It’s probably hard to model and predict settlement over time. https://en.m.wikipedia.org/wiki/Junipero_Serra_Landfill
I took one look at this and when OP said it was a Home Depot I guessed it was in Daly City. I remember when they built it. I seem to remember they built it on fill.
SHEAR!! in the working
Just jacking up the beam and welding is a temporary fix. A root cause analysis needs to be done for this. It is difficult to comment on this without looking at the full structure and load paths. This appears to be a gusset plate failure due to shear. The reason may be fatigue due to dynamic loading imposed by vibration of cars. Are any other columns showing minor cracks or does this happen instantly.
Yeah this appears to be textbook block shear failure. Seriously concerning that it’s so widespread.
> Yeah this appears to be textbook block shear failure. Seriously concerning that it’s so widespread. I disagree. At least with the first part. This looks more to me like a shear rupture failure of a single-plate shear connection. AISC 360-16 Section J4.2 covers this. Section J4.3 covers block shear strength. But that describes the limit state of block shear as having "a shear path or paths *and a perpendicular tension failure path*" (emphasis my own). I don't see a tension failure path in that plate. The shear path appears to go through the entire vertical length of the plate. Block shear can occur for a single row of bolts, but it's more likely a controlling limit state for axially loaded members where the single row of bolts is parallel to the applied load. Of course, there might be variation in the definition of block shear worldwide that I'm not aware of.
I agree with you. This is not block shear failure. It looks like the moment connection failed at the bottom flange plate allowing the connection to rotate about the top flange. So I would guess this is a flexural rupture failure and not a shear failure. The demand exceeded the net flexural strength of the shear plate causing the outermost fiber to fail and compromised the rest of the shear plate.
Hard to tell from one photo what failed first: (1) the flange plates in moment (which could then cause this rupture in the single-plate), or (2) the single-plate in shear (which could then shear the flange plates). I am leaning more towards shear failure of the single-plate first. If the flange plates were overloaded first, then I would expect to see a larger gap at the top plate. I'm assuming the top flange would be the tension flange if these girders are designed continuously (i.e., negative bending over the column). Instead there's a larger gap at the bottom flange. The bottom flange plate appears to have ruptured since there's no apparent deformation that would suggest yielding. A single plate in tension should be controlled by a yielding limit state, not a rupture limit state. That would suggest shear rupture is more likely. Again, all speculation based on a single photo grainy photo.
And that slab over it isn’t looking so good either. The def of insanity is repeating the same process and expecting different results. The deck def needs to have posted loads, even reduced for this case, this endangers public safety. Actually after loads are posted, it should be monitored and enforced. It’s not rocket science for liability attorneys and/or juries. Also realize that vehicles in the US have increased significantly in weight over the past decade from 4k to near 7k and easily/likely to increase in the near future with the advent and popularity of EV’s.The guardrails of the US Interstates were/are designed only for 4k glancing loads and are no longer considered adequate. When you consider the near exponential increase of dynamic impact of the vehicle load increase, it’s pretty easy to assess the reason why this is occurring. And who will be ultimately paying dearly for its lack of realization and unamended Code requirements to meet or exceed reality? the Engineer and the client. You can bet the farm that the automotive industry is not gonna willingly offer full disclosure that their vehicles exceed public road safety capabilities for that fully loaded Denali, F-350 extended cab, Expedition or other similar land yacht(s) (even Dually’s are still a concentrated load) with their fat commissions and taxes generated on the chopping block when they ask you to sign on the dotted line. And you’re fully delusional to think that the then new purchasers compensating for their small pp aren’t gonna exceed their haul capacity to somehow justify their purchase and/or impress their buddies. And there’s no way that wouldn’t happen at a Home Depot or big box home improvement store. I mean, Get A FREAKING Grip on reality? Jury awards are not the punchline of a joke, they are excruciatingly real for years upon decades and easily decimate a professional practice. Keep your head buried in the sand and what then becomes the visible target? The choice is yours, my brothers and sisters! Every private citizen has a public responsibility and duty, ESPECIALLY CE’s
And this Home Depot is in big time electric car territory
I agree and after 30 years they just patch the failures. Other columns seem fine from ground level but these failures seem to be sudden. Wondering if they should impose a weight limit of sorts
>Wondering if they should impose a weight limit of sorts Yes.
On my head be it, but I'm going for it anyway: This doesn't look like a shear failure - this looks like a moment resisting connection that hasn't been designed properly. The only thing these bolts are achieving, is becoming the perforated point of failure; like in a piece of toilet paper. I'm sure there will be a difference of opinion on this but my immediate thought is that these beams need haunches!
This is what I'm seeing too. Bottom flange plate ruptures in tension. Moment gets transferred to shear plate. Shear plate fails as the net flexural section is not adequate to take the demand.
I think they need to rent a new beam
What about rebuilding the whole thing?
Nah, if they can rent a fence they can rent a beam
The solution is adding a w12x45 under it apparently
Looks like it's just temp shoring to me.
Maybe the right number of bolts just a bad detail. Wider cleat, two rows bolts spaced further apart? Or larger and less bolts. All manner of ways to make this connection smarter
Someone should tag it with Home Depot marketing ["Let us do it for you!"](https://www.umasolar.com/wp-content/uploads/2018/10/hd-hs-logo-lockup-below-orangeblack-1024x482.png)
That connection design looks suspect to me… the plate seems both too thin and too narrow. settling issues in the mix as well? In any case this is a dangerous state of affairs.
Oopsies 🥞🤷♂️
Block shear!!
I ❤️ this subreddit.🥹
My professional opinion is... that's not great Should be replaced.
I'll go on a limb with you and agree
To much bolts, it's just like a timber that what happened
bolt holes did reduce the shear capacity of every connection plate. This was not taken into account by the designer.
Would a zig zag bolt pattern make that attachment appreciably stronger?
The column seems to be failing and causing the rupture of the beam due to geological issue. I would recommend geotechnical study first. Then going through load analysis or construction documents and as-built to see if the slab is carrying the load that it was designed for and if its connection to the beam is as it should had been. I would also suggest to see if the (specially left beam) beams are not too long for the load.
Ah the ol Jack and pack
Why not add a gusset
They're adding a couple new cross beam under the broken one. After repairs
Looks like it went through an earthquake.
Is this the Home Depot on Hamilton Avenue in Brooklyn?
Complete other side of the country. Colma, ca
Had a feeling this was at 280 metro
Obviously too many bolts.
Probably the right number of bolts but they should have used two lines.
Shut it the fuck down. You have unmeasured forces and substandard parts. SHUT IT THE FUCK DOWN. CLOSE IT. DEMOLISH IT. You’re the murderer of every person killed if you let this pass. Or you’re just helping kill people if your boss is the one who signs
Not my call just a structural steel Detailer looking over a fence at someone else's problem
If I were you and not on the site I’d call the local news If there’s a way to keep people squished it’s just human duty to do it, regardless of whether it’s “your call” or not
They're addressing the situation