HSS column under 1500kN Uplift Base Connection Design

[Enger2022]

Hi there, I have an HSS 178X178 column (supported on the concrete column below) under an uplift of 1500 kN. Since this load is huge, I can't find any anchors that work. I am thinking to embed the baseplate in the concrete with fillet welded reinforcing bars that are spliced with the column vertical bars with enough development lengths. Do you think this will work? What is the minimum rebar spacing for fillet welding? Thanks.

Thanks, everyone, for the reply.
It's about the column base design of a moderately ductile braced frame. The HSS178x178 column is to be centred with 200mm concrete walls. I am to design the base connections for edge and corner columns, both centred with the wall.

 

[Tomfh]

Can't you cast in some long anchor rods, lapped with the column bars?

 

[HTURKAK]

IMHO, you can find anchors as long as the column HSS 178X127 and the footing can resist uplift force of 1500 kN..












Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[ALK2415]

check this Ref
its full of steel to concrete connection ideas and procedures

https://drive.google.com/file/d/1TOVDjTkN7q4BUvUs08HBqh3hiJF5zAfU/view?usp=sharing

 

[JLNJ]

Even as a factored load, that's getting close to the full yield strength of the shape (and that's assuming it's an HSS 7x5x1/2, the thickest in the book).

I think you will have a hard time making a conventional-looking baseplate work. Full-pen field welds of the column to the base plate will require special geometry and procedure. You will need to mill a backer to fit inside the column shape. You might be able to cast a mirrored shape of the tube into the pier with a myriad of headed studs on it and full-pen weld that piece in the shop to the underside of the base plate.

Send us a little more on your geometry/loads and you might get folks here to generate some ideas. There are some really smart people with eyes on this forum.

 

[dold]

I can't find any anchors that work.

For 1500kN? Like 350 kip? Just use more anchors? Bigger anchors? What part of the anchor isn't working? 350 kip isn't *that* much. You could easily get (4) 1-1/2" Dia Gr105 anchors to work out if youre trying to minimize congestion in the column.

 

[Enger2022]

Thanks, everyone, for the reply.
It's about the column base design of a moderately ductile braced frame. The HSS178x178 column is to be centred with 200mm concrete walls. I am to design the base connections for edge and corner columns, both centred with the wall.

 

[dik]

Even using ASTM F1554 Gr 105, you are looking at some very large anchor rods... and not weldable. Using a rebar cage and properly designed headed anchor rods, it can be done without too much difficulty. The loads are huge and have to be resisted by something.

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

-Dik

 

[dik]

0.375 should just squeek... with fy = 50 ksi... and little moment... and probably a 1/2" fillet weld around the base. and not A500 (never spec that).


That's a lot trickier...

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

-Dik