Post-installed transverse ties in foundation wall 2

[milkshakelake]

Is it possible to post-install column ties in a foundation wall?

I have a foundation wall that was installed without transverse ties, but it has a concrete column on top of it with about ultimate 450 kips axial load. Per ACI 318-14, ties are required:

11.7.4 Lateral support of longitudinal reinforcement
11.7.4.1 If longitudinal reinforcement is required for axial strength or if Ast exceeds 0.01Ag, longitudinal reinforcement shall be laterally supported by transverse ties.

 

[BAretired]

Could you drill through the wall and install through bolts?

 

[hokie66]

Size of column? Thickness of wall? Why do you think 11.7.4.1 applies?

Is there a horizontal element, beam or slab, between the wall and the column above?

 

[milkshakelake]

@BAretired I added a sketch. I can't install a thru-bolt because one of the sides is soil. I was thinking of epoxying bars to act like ties, but they're not really hooked and don't function as true ties. The other thing I thought about is to pour a new 24x24 concrete pier next to the column within the foundation wall, which will have ties, and that will be dowelled into the wall. It's just a bit janky in terms of strictly adhering to code.

@hokie66 Added a sketch to clarify. Yes, there is a slab to be installed. Col is 10"x22" and wall is 12". I think the code applies because there is a significant axial force in the wall that comes from the column. It's going to be a 7 story building. Edit: One more reason the code applies is because a building official said so, and what they say is gospel. I wrote a 2 page essay with free body diagrams and stuff showing that it's not necessary, and it got rejected. I'm not arguing with it anymore, just trying to comply.

 

[hokie66]

2 ksi bearing at the base of the column. That dissipates through the slab. There is no need for restraint of reinforcement in the wall, no matter what the 'building official' says. Ties are not required for axial strength, and I doubt if the wall has 0.01Ag reinforcement, and if it did, the bars would be for flexure, not axial. GEEZ!

 

[Greenalleycat]

Whether you can argue around it or not, the original design seems strange
If I've mathed mathily then 450kips is about 2000kN coming down that column which is 10" wide x 22" deep?
This then transitions into a 12" wall - if that wall is 12" deep and the column is 22" then what happens at the transition?
Why was the column not just carried down to foundation level originally? Or is it 10" deep x 22" wide?

The 12" wall is labelled existing - does that mean "poured yesterday" or is this adding 7 storeys on top of a pre-existing basement?
If adding 7 storeys, it seems reasonable to me that the inspector would want you to cut the wall or whatever to put in a compliant bottom column level

 

[milkshakelake]

@hokie66 I was thinking of how the slab would dissipate the force. Without getting into FEM modeling and vertical stiffness of the slab edge and/or foundation wall, I was thinking of a 45 degrees distribution (similar to CMU above lintels, as shown in NCMA Tek). Does that make sense? Alternatively, I could provide some kind of haunch to make that a definite reality.

@Greenalleycat The column is 10" deep x 22" wide (22" being parallel to the ~100' long foundation wall), so a 10" member is coming into a 12" one. As for why the foundation wall is existing, it was poured along with footings around 2021 with the intention of carrying 7 stories. There were numerous deficiencies in the construction because it was built according to a temporary "dummy" set that was submitted only to get the filing in. The foundations/walls sat for years and I'm trying to get the construction back into action. Besides this little item mentioned here, I've submitted about 100 different reports and calculations to get this back on track. It's been quite a journey. Anyway, it's out of the question to cut out the foundation wall to put in something better, because the wall is retaining soil and adjacent surcharge. But adding a pier/wall to the inside is fine, which is what I'm considering.

 

[BAretired]

The existing strip footing does not strike me as adequate for a 450k concentrated load on top of the wall. There should be an enlarged footing under the load.

Adding a pier on the inside will not help if it lacks adequate support at footing level. It is unlikely that the First Floor slab can contribute enough resistance to such a high column load.

The existing wall should be reinforced as a deep beam to spread the 450k load over a reasonable length of strip footing.

 

[milkshakelake]

@BAretired I didn't put it in the sketch, but I'm extending the footing quite a bit with a lot of heavy reinforcement. You're right that the strip footing is totally inadequate.

 

[OldDawgNewTricks]

450 kips is a substantial concentrated load. Even if you spread it out at 45 degrees through the floor slab thickness, it will still be in the range of 0.1f'c to 0.2f'c depending upon the concrete strength used for the wall. I would tend to agree with the building official and would want confinement. Adding something to the inside face wouldn't really provide confinement to the outside face though. I think I would bite the bullet and figure out a way to shore an excavation so that the confined column could be extended down to the foundation.

 

[SWComposites]

MSL - I sure hope they are paying you well for the 100+ reports and whatnot to salvage what sounds like a complete mess.

 

[hokie66]

OldDawg,

It is 2 ksi direct bearing. How does that translate to 0.1f'c if spread out?

 

[OldDawgNewTricks]

hokie66, assuming the new slab is 12" thick max and the load spreads out at a 45 degree angle, then the effective concrete area at the bottom of the floor slab is (22"+2*12")*(12")=552in^2. The compressive stress is 450k/552in^2=0.815ksi which would be 0.2f'c if 4ksi concrete was used for the existing wall or 0.1f'c if 8ksi concrete was used.

 

[hokie66]

You are correct. I have been too long using MPa for concrete strengths.

That being the case, perhaps a spreader under the column above the floor would be appropriate to engage enough of the wall below. But that might not solve the footing issues.

 

[milkshakelake]

@SWComposites I'm getting paid a fair rate, otherwise this project would be going into the trash bin. I do feel a little bad for the officials on the other end that have to review the 100+ reports, but they're the ones that wrote the laws.

@OldDawgNewTricks I ran a calculation to see if it works as plain concrete (ACI 318-14 14.5.3) and it does, so I think that's enough justification to say that longitudinal bars are not needed for axial strength. I agree with hokie66 that the bars are only needed for flexure.