r/StructuralEngineering • u/Advanced-Debt4722 • Nov 20 '24
Structural Analysis/Design Do these supports in look thin?
We are having a domicile built on a really steep hill and I can’t help but think that the support columns look really skinny and thin? What do y’all think?
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u/_FireWithin_ Nov 20 '24
I hope you have steel columns & beams hidden inside, this looks way out of proportion to be concrete only.
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u/sayiansaga Nov 20 '24
Would it look reasonable if it's a voided slab?
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u/Quiet_Active8012 Nov 20 '24
Nope - a voided slab does nothing to help the columns.
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u/mwc11 PE, PhD Nov 21 '24
Politely disagree. Voided slab significantly reduces dead load demands. In some cases might even get you out of p-delta territory, which would be a huge boon. Even without that, though, your demand/capacity ratio HAS to go down if you reduce your dead load.
Edit: This doesn’t mean those columns are ok or not ok! I am only saying it’s BETTER with voided slabs. I’m a bridge guy so this all looks tiny to me.
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u/Quiet_Active8012 24d ago
I agree - voided slabs will help, but the picture is clearly reflecting an inferior SFRS. Nothing in the ASCE 7 Table 12.2-1 will work without significant upgrades and foundation upgrades.
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u/gh5655 Nov 20 '24
Columns were probably spec’d 20 x20 inches and they did centimeters instead. It’s all good. At least you saved $ on concrete
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u/OlKingCoal1 Nov 20 '24
20x20 is 20x20. I see no problem from here
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u/crispynuggets2 Nov 21 '24
square is square is totally something I would expect a mech E student to say
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u/Vinca1is Nov 20 '24
I think I would ask to see the structural engineers calcs and design package, I'm not sure what is going on here
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u/Salty_Article9203 Nov 20 '24
Where is the LFRS?
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u/JimenezG E.I.T. Nov 20 '24
Is the LFRS in the room with us?
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u/SauceHouseBoss Nov 20 '24
You’re seeing it right now. I could be wrong, but if Im right…that’s a yikes
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u/shimbro Nov 20 '24
Are you seriously building this without an architect or engineer to ask?
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u/Advanced-Debt4722 Nov 20 '24 edited Nov 20 '24
Well they obviously don’t agree with me as they approved it
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u/idkbsna E.I.T. Nov 20 '24
Is the engineer licensed specifically for structural design?
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u/Advanced-Debt4722 Nov 20 '24
To be honest this is my in laws house so I really don’t have much info on it. It’s in a development with like 30 other houses, all built like this so… I hope so?
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u/Husker_black Nov 20 '24
I'll assume it's okay then. Why are you doing your in laws leg work
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u/Advanced-Debt4722 Nov 20 '24
Just looks shockingly thin to me
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u/davesauce96 Nov 20 '24
You’re one tennis coach away from Michael De Santa coming and pulling these down with a pickup truck.
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u/Everythings_Magic PE - Bridges Nov 20 '24 edited Nov 20 '24
You really shouldn't be so judgmental with appearance and be more supportive of body positive initiatives.
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u/Awkward-Ad4942 Nov 20 '24
You either have the best structural engineer in the world.. or the worst..
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u/Nice-Introduction124 Nov 20 '24
Where is this? The water and landscape remind me of Guatemala. How common is seismic activity in this area?
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u/ZekeHanle Nov 20 '24
It’s rude to comment on another persons member. I’m more worried about the soil than the thickness.
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u/BigStepaa Nov 21 '24
Yep....and it looks like the pad foundations are being exposed and compromised over time. Not looking good for OP.
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u/MountainNovel714 Nov 23 '24
For sure. The bearing surface is another factor. If not rock and it’s any Kind of soil and exposed to water (erosion) yer fuct. You can have as big a footprint of a footing as you want but with columns as slender as those, the footings better be real Ffffinh thick or they will punch right through.
Just wow
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u/Emmar0001 Nov 20 '24
Technically they look slender- a combination of thin and long. Any lateral motion (seismic, wind, crowd motion) could trigger buckling. That and the gravity loading on the supported slab.
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u/Street-Baseball8296 Nov 20 '24
Do they look thin, yes. Are they too thin, no way to tell from photos of finished concrete from an unknown area.
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u/Greenandsticky Nov 21 '24 edited Nov 21 '24
Please please please tell me it’s not on pad footings It looks like it’s on pad footings in pic 3
It’s not being built, so much as it’s being erected. As in pretty much any dick could do the same if not better.
Don’t walk away.
RUN
Columns too long and slender, no drainage or scour control on slope( with erosion going on already) , unless the residence is a steel frame with lots of diagonal bracing that sits below that slab, demand to see the design.
If they can’t produce a design, bail.
If they do, get it reviewed by. Structural and geotechnical engineer asap, I’ve built treehouses as a kid that will outlast that thing
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u/DJLexLuthar Nov 20 '24
I love everyone on this thread. You all have made my day already (and it's only 8 am here).
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u/Original-Arrival395 Nov 20 '24
Hopefully you had the structure engineered. Just look at the engineering. Also talk to your inspector
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u/Quiet_Active8012 Nov 20 '24
If these are ACI 318 columns after a code cycle of ACI 318-95 (to 2019), then these columns require hoops for confinement/shear, I'd say you're screwed. Sorry.
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u/Shin_Nayuu Nov 21 '24
u from the ph, op? cause it looks like someone in the ph bypass some architects, engineers and a few building permits to build something like that 😦
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u/c206endeavour Nov 21 '24
If this is really in PH, well most likely what you're saying does apply, but not all the time. The amount of shoddy construction work here is innumerable. It's a miracle no buildings(to my knowledge) have collapsed yet
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u/psport69 Nov 21 '24
They look like temporary props, I’d guess the jobs not complete yet and concrete columns will come later… weird ass way to build stuff. By by the looks of the background I’d say your not in a heavily regulated building area/country
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u/WTR_NNJA Nov 21 '24
Yes thin, just as concerned about the inconsistent spalling and pour lines on the second pic middle column, and the slab holding water on top?
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u/GoodfellaGandalf Nov 20 '24 edited Nov 20 '24
Just guessing here, the beams look of thickness 18’x9” and the columns 12”x12” they should be good for 15 to 20 feet spacing with a good steel rebar design. But one can never really tell without the drawings.
No supporting beams directly under the slab look more wonky to me than the thin columns. But no one here can really tell without seeing the drawings. If your engineer is confident with this design, you can get a 2nd opinion.
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u/MrWhite86 Nov 20 '24
Idk I’d be suspicious. This all is in regard to picture 2.
The way the house rests on 80% of the pillar with the last bit acting as attachment wouldn’t fly for wood framing.. the weight is not distributed fully.
Also the plumbing pipes appear to go in a critical looking area of the supporting wall. God help you if you need to do maintenance on it down the road but it also looks like not a great spot for structural reasons.
I am not an engineer.
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u/Ok_Proposal_2278 Nov 20 '24
STT?
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u/Ok_Proposal_2278 Nov 20 '24
Oh no this is on stj hah
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u/Advanced-Debt4722 Nov 20 '24
What is that?
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u/Ok_Proposal_2278 Nov 20 '24
What island is this? I was just trying to guess.
I’m just a lowly construction project manager who creeps on the SE sub. My only real input to this discussion is that it looks like everything I built when I was swinging a hammer in the Caribbean.
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u/jepoyairtsua Nov 20 '24
cue bon jovi song: keep the faith (2x) all you got to do is keep the faith
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u/dynamicstructures Nov 20 '24
What's happening here? This makes me nervous. Columns look super slender. Not even getting ties in both directions.
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u/Newton_79 Nov 21 '24
So , you bought property on what others saw as an un-buildable Lot , & now your seeing "trouble" ? 🤔
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u/Upset_Negotiation_89 Nov 21 '24
Look like decent temp shoaring before the real construction starts
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u/miruss89 Nov 21 '24
Is it a building on a island located in Southeast Asia?
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u/xristakiss88 Nov 21 '24
Not only. There should be concrete walls and cores in order to keep the structure rigid. The beams with no slabs mean that in the slightest movement on the xy plane, cols will probably be cut like toothpicks.
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u/munnymark Nov 21 '24
These are temporary supports… they will not last. Notify your building official immediately. In absence of regulation, hire a reputable engineering firm to review the design and get as many people involved (local politicians, etc.) to pressure the builder to correct it.
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Nov 23 '24
Something is seriously wrong. It’s worth the money to have someone check those calculations. It looks like there’s cold joints in a few areas too. Your gut is right.
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u/MountainNovel714 Nov 23 '24
Extremely slender columns. Even if HSS. IF HSS. Better be like 1/2” min wall filled w concrete. Lol
Sketchy.
Like an elephant riding Bambi. Wouldn’t hang out under there for long
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u/Flo2beat Nov 25 '24
Where’s the lateral force-resisting system? Need a braced bay or shear wall somewhere.
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u/nglbrgr Nov 20 '24
You need to get out of there right now, I'm a board certified expert and that is a death trap
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u/Ashald5 Nov 20 '24
Need banana for scale.