Tie Reinforcing Axial Loaded Column

[Eng2Ski]

Hello, looking through ACI 318-08, Section 7.10.5 - Ties, it appears that the tie reinforcing geometry shown in the attached image is acceptable. I have a shear lug in the center of the pier, so it would be desirable to use the geometry I have shown. Is this tie geometry okay?

 

[KootK]

Just when you' think you've seem every possible column tie arrangement... This is a tricky one.

I think that your proposed arrangement satisfies the letter of the code. However, the angled cross ties restraining the four side bars bother me. I'd prefer to:

1) Use eight slightly larger bars and bundle them in groups of two at the corners, eliminating all cross ties or;

2) Add candy canes to turn your coat hangers into triangles and shift the bars towards the top and bottom as necessary to clear your lug pocket.

Given the same reinforcing area, both options should actually increase the capacity of your column.

You could do something with a single, off center diamond tie but those are out of vogue for constructability reasons these days.





I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Eng2Ski]

Thanks for the advice KootK.

One other thing, this concrete pier is only 1' tall, it just extends out of the footing to get to the bottom of column elevation. So this is an image showing what I submitted to Building Safety as a field change order, with the baseplate and shear lug added:

They approved it and the contractor is happy with the fix.