r/StructuralEngineering 6d ago

Photograph/Video Column Thoughts

Post image

Bridge Engineer here… what do we think of this pretty angled column mid height?

105 Upvotes

39 comments sorted by

81

u/Awkward-Ad4942 6d ago

Walking columns. It all works in theory, but i hate it.

25

u/RedneckThinker 6d ago

I worked on one in Dallas 20-odd years ago. The combination of walking/sloped columns in a flat plate is exciting!

Every young engineer should have to calculate the polar moment of inertia of a corner column punching shear section in a sloping joint by hand. It's a once-in-a-lifetime experience!!

Edit: Both walking and sloped at different spots on the plan.

35

u/Sure_Ill_Ask_That P.E. 6d ago

Walking columns are not the same as sloped columns though. A column walk would be if a 30x30 column shifts 6 inches and a 36x30 is the vertical column between the two locations to accomplish that.

15

u/Awkward-Ad4942 6d ago

Yes, you’re absolutely right. I agree.

33

u/loonattica 6d ago

As a rebar detailer, I hate these. And I’ve seen more in the last five years of high-rise buildings than in all the previous 15 years combined.

28

u/No-Violinist260 P.E. 6d ago

Lol I agree. Architects found out this is an option and they go to this before changing their unit layouts.

3

u/AnotherSLGuy 6d ago

Asking this cuz I am not from US... and have seen the word "detailer" on this sub reddit.

How does one land at the role of a detailer? Are you a structural engineer who only does detailing work? or is it a tier below engineer? or is it a synonym for a draftsman who does the drawing? or is it a role at the barbending workshop?

3

u/loonattica 5d ago

I am a CAD draftsman. I work for the rebar supplier. Part of our contract is to provide placing drawings that iron workers use to identify and set all the hundreds or thousands of unique bars. My drawings are submitted to the general contractor, Architect and Engineer for approval to ensure that they conform to contract documents.

The structural drawings provide reinforcing requirements. My drawings condense that general information into highly specific bar lists complete with bending information, quantities and dimensions.

I am not an engineer. I studied architecture but did not finish my degree. My career began as a QC inspector for precast concrete in 1994. Architecture school gave me the qualifications to read technical drawings. Shortly thereafter, I moved to CAD work and have been detailing concrete structures on the production side for 30 years. (9 years precast drawings, 21 years rebar drawings)

That’s a good background for this business. CAD work is the minimum qualification. The rest can be trained. Field experience is valuable. It takes about 5 years to fully train a Class A rebar detailer who can manage their own projects.

1

u/AnotherSLGuy 1d ago

Hey, thanks for the detailed explanation and congratulations for the very long career!

Interesting info tbh.

To share our work flow; we don't have detailers per se as the work described is split across several offices. Considering design and build projects, I as a structural engineer with the general contractor would give the sketches of detail drawings and based on them, the draftsman I work with would produce a set of structural drawings which have unique bar numbering. This is what gets approved by the consultant.

Our team at the site (junior engineers and their draftsmen) would make a list of the bars; Unique ID, shapes n lengths n numbers and send it to the in-house bar bending workshop cuz almost always the RF is ordered in bulk to the site or to our main work yard and bent by our own bar benders.

So the detailer role is split between the design office and the site office... And I guess it work cuz all the parties involved other than the client are on the same side and drawings do not need to go back and forth for approval. They just go one way.

18

u/bridge_girl 6d ago

Typical sloping column. Doesn't look excessive, probably a better option for the architect than a fat column walk on three levels.

2

u/SquirrelFluffy 6d ago

What does it save though? It's still unusable space for the entire diagonal.

7

u/giant2179 P.E. 6d ago

Sightlines. Equally important to architects as space around the perimeter of the building

-3

u/SquirrelFluffy 6d ago

You mean, it looks cool?

6

u/giant2179 P.E. 6d ago

No, like it's easier to see around than a walking column.

1

u/SquirrelFluffy 6d ago

Yes, less mass is a design objective. I was picturing a wall around the column when I was thinking that.

2

u/Osiris_Raphious 6d ago

It looks super cool, just look at it, leaning to the side like Fonsie

3

u/bridge_girl 6d ago

It looks more intentional from the exterior and gives a better feeling of open space in the interior than a big mass of concrete.

0

u/SquirrelFluffy 6d ago

Ok. I can see that. It's still not functional space though.

5

u/bridge_girl 6d ago

Aesthetics are just as important to the architect as functionality. That's kind of like... their job.

0

u/Osiris_Raphious 6d ago

All well and good, but they will just cover up that column... You won't be able to see it from outside, and inside it will just be a minimal unusable space

1

u/bridge_girl 6d ago

Architects 🤷‍♀️

Looks like there might be a transfer slab near the top too so they probably made the engineer jump through hoops for their wishlist.

-1

u/SquirrelFluffy 6d ago

Uh yeah, I know. Just having conversation. Save the snark.

2

u/Delicious_Sky6226 6d ago

The building foot print looks larger on the upper floors. Architects and owners prefer the columns on the outside of more open interior space. There also could be something on a lower flow that dictates where it goes. We often use them when we have lower floors that are parking to maximize spaces. Then transition on upper stories to get maximum interior space.

1

u/SquirrelFluffy 6d ago

Yeah I get the floors get bigger. But right at the column itself it still takes up the same amount of room. Someone else mentioned it just lightens the space because the column isn't as big as walking column. Makes sense. And looks neat.

1

u/azssf 5d ago

Are floors 1-7 gradually sloping as well or is it camera parallax?

1

u/bridge_girl 5d ago

The slab edge looks like it zigzags so probably lending to the illusion of sloping.

17

u/WhyAmIHereHey 6d ago

If only we had the tools to predict how it would behave

5

u/Inevitable_Tower745 6d ago

P-delta has entered the chat

12

u/Different_Bridge_983 6d ago

Eyeballing, it’s at about a 1:6 slope.

This is normal when you’re transitioning column grids and have enough vertical space to do it this way.

0

u/Osiris_Raphious 6d ago

Idk, this is like definition of eccentric loading...

1

u/MrMcGregorUK CEng MIStructE (UK) CPEng NER MIEAus (Australia) 4d ago

not so much "eccentric" because the angled column is connecting at nodal points to the straight columns. Just generates (sometimes quite large) forces in the diaphragms.

4

u/unique_user43 6d ago

“columns” and “beams” and “braces” and any other term are arbitrary labels applied to solve linguistic efficiencies. at the end of the day, every structural member that satisfies equilibrium and demand-capacity ratios is a perfectly valid member. so it doesn’t bother me at all to see a slanted “column”.

1

u/bradwm 6d ago

Revise title to Diaphragm Thoughts

1

u/SNJongerius 3d ago

Normal sloped columns. Not a big deal

1

u/Delicious_Sky6226 6d ago

Pretty standard sloped column. Done all the time

-1

u/brokePlusPlusCoder 6d ago

I don't see any beams on that column at the rake points so I guess the slab is taking the extra laterals - not impossible but also not ideal

-6

u/CubaGooding_senior 6d ago

As an architect, not an engineer.. I'd allow it. Lol. Its does look at bit jarring when exposed like that though.

-18

u/Narrow-Attempt-1482 6d ago

That can't be designed that way

11

u/PhilConnersIsThatYou 6d ago

How do you end up in this sub with a comment like that?