Column Pier Design 2

[FEM4Structures]

Hi,

Concrete Support Piers are for steel building columns (Butler Building). Piers are part of foundation wall system. GC forgot to install vertical rebars. Trying to come up with field repairs.
1) Is it correct to consider the wall flanges on either side of piers in resisting Tensile Uplift assuming the concrete section unreinforced.
2) Anyone has experience with concrete jacketing the pier and response of such a repair.

Response much appreciated.

 

[FEM4Structures]

Forgot to mention that 1.5 * h (effective) distance recommended in ACI 318 Appendix D terminate at some distance within the flanges on either side of the pier. I normally assume the pier perimeter to resist the uplift, however for the repair at hand I am trying to include every bit of concrete in design I possibly can.

 

[hokie66]

Stupid contractor needs to knock it out and start over.

 

[marinaman]

I agree with hokie66.

I know, from experience, that that is a tough call to make, but, sometimes, there's really not much of an alternative.

Given that you will not have any tensile reinforcing anywhere within the concrete block, I would not feel good about any repair to the pier. Forces to the pier will constantly vary with lateral loading. If you guys experience a big storm or high winds for a short period of time, and the pier cracks, then essentially you'll have no vertical nor moment tie of the columns to the foundation.

Unfortunately, he's going to have to demolish the piers.

You might be able to keep the foundation below the piers. Assuming you have spread footings supporting the piers, you may be able to then epoxy dowels into the existing footings that remain, build the rebar cage the pier should have had to start with, and then repour the piers themselves, but again, it depends upon the loads and how the building would be used. If the building will have cranes and such in it, is near hurricane or seismic areas, or has some other load case requiring attention, then this may not be a good solution either.

 

[FEM4Structures]

What is your opinion about following repairs?

Option 1:
Make the pier size bigger with Concrete Jacketing. Rough up the exisitng pier surface, apply appoxy, use vertical dowels, shear ties and concrete jacket.

Option 2:
Since the pier is the part of the foundation wall use part of the wall in resisting tensile breakout treating the section unreinforced?

I am exploring the option where I dont have to demolish the concrete as steel will show up in a week.

 

[structSU10]

I think demolish and rebuild is the only good option. What if you already have a shrinkage crack or something across the pier? And once it starts to crack at all, you lose effective section to resist the forces, and it would just unzip. If you can detail a jacket to transfer the loads to appropriate vertical steel, maybe that would work, but I wouldnt feel very comfortable about it especially considering that its a PEMB on top that I had no control over the design of.