Remove concrete column

Question

Remove concrete column

buckling beam (Structural)

(OP)

16 Sep 20 08:54

Hi my fellows engineers!

I'm an italian strucutral engineer, working as an independent consultant, and I'm here to share with you a new problem and maybe get some solutions/tips.

Here's the thing: yesterday, I went to an office building (inside a warehouse) which is meant to go under renovations beacause of covid-19 (they need extra space between working places and larger circulation corridors). Among some easy stuff to calculate, there's a column at the entrance that needs to be removed, so they can have a bigger entrance door to allow 2 separate corridors - one to enter and one to leave. Attached you can find 2 drawing: one showing the existent and another showing my idea to solve this problem.

My doubts are basically:
- connection between UPN beam and existing concrete beam with anchor bolts in site?
- torsion moment in the UPN beam?
- bolts only in the width of the existing column or over the length of UPN beam?
- calculate the smash of UPN beam web like we do with steel base plates?

I can't put a beam under the concrete beam already there because there's no height....

Any help would be very much appreciated!!

https://files.engineering.com/getfile.aspx?folder=74ef8b1b-86a4-4181-965b-0

HTURKAK (Structural) · Answer 1 · 2020-09-16 11:53:18

The attached picture shows only one sketch and showing your idea. Apparently the sketch is for removing the column at entrance level and the proposed UPN beams and IPE columns to transfer the upper storey load.

Without knowing the full picture ( the structural system ) it is hard to comment.

If the column is a member of main force resisting system, DON'T DO THAT !

buckling beam (Structural) · Answer 2 · 2020-09-16 12:42:23

The structural system is attached to this post. It's a very basic portal frame, where I know exactly the load and the span of each beam. The beam in particular, is in the façade, so this portal frame in study has got the least loads of them all.

I can easily calculate the loads on the portal frame, and find the "reactions" on top of the column to be removed...

C'mon, I can't be the first structural engineer facing such problem, and there's got be a way to solve this...

(I hope)

https://files.engineering.com/getfile.aspx?folder=163ede6b-802f-4bca-9f47-e

HTURKAK (Structural) · Answer 3 · 2020-09-16 14:20:36

Quote (It's a very basic portal frame, where I know exactly the load and the span of each beam. The beam in particular, is in the façade, so this portal frame in study has got the least loads of them all.)

The second sketch apparently shows the column is a member of FRS rather than an architectural element. Without knowing the full structural system, seismicity I will not comment.

r13 (Civil/Environmental) · Answer 4 · 2020-09-16 15:17:08

You will need significant built-up to replace the to be removed column in the middle. UPN beam is a drop in a bucket, I believe. Can you increase the concrete beam from above? Or consider other external strengthening methods?

buckling beam (Structural) · Answer 5 · 2020-09-16 16:30:42

Yeah, that's what I'm affraid of, and from my first calculations, web thickness of UPN won't be enough...

I can't increase the beam in any direction - below it wouldn't allow people do pass through and above I've got high windows from floor, and besides it's the main façade...

I'm trying to reach an "easy" solution, interfering only in the entrance

r13 (Civil/Environmental) · Answer 6 · 2020-09-16 16:51:07

I'll perform analysis without the column to see the effects. I believe the adjacent structures will be affected by any of the the proposed changes/replacement. As it would be quite involved (the modification will involve more than just one beam), I would go over with the owner to find better alternatives.

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Remove concrete column