ICF Wall Opening Jamb's, Point Loads

[dhoward26]

I'm starting to get a little more into ICF designs for custom homes and have some questions about columns and jambs.

For openings, where in the ACI code does it talk about when you need to provide ties and when you don't? ACI318-11 Section 7.10.5.1 states that "All nonprestressed bars shall be enclosed by transverse ties" when talking about compression members. What are the limits as to when you do or don't need to provide ties? And for Jambs, should I provide the minimum tie spacing required for all Jambs? Most loads on the jambs aren't more than a few thousand pounds.

I don't plan on using the waffle system of the ICF's to support larger point loads. I have some point loads from Girder Trusses that are around 5,000 lbs and it just doesn't seam too logical to provide a tied column under this when it is coming down on a wall and no opening. I will direct the contractor to provide a vertical bar underneath of it though. The wall systems are generally laid out such that my columns aren't part of the main lateral force resisting system. They support vertical loads and out-of-plane lateral loads from the openings only...except very special cases.

 

[msquared48]

Interesting thought here.

In most residential concrete foundation walls, column ties are not used. I really never use them unless the load is substantial, and that is a gut call, not ACI related.

However, it is much more likely to occurat the the wall openings supporting PT slab or RC slab construction.


Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[dhoward26]

I agree with a typical foundation and retaining wall. But with the ICF I'm using, it is a waffle grid and I'm not sure if arching action applies with ICF waffle grids...haven't found literature on that yet.

The other thing, the top of the openings of my doors/windows are 8ft. I have one load that is approaching 15,000 lbs so I will definitely puts some ties in there for that one. But for a typical opening that has say 5,000 to 10,000 lbs coming down on it, I can't find anywhere in the code that states I do or don't have to have a tied column or at what point with combination vertical/out-of-plane lateral you need to provide a tied column system.

I don't want to completely over-design the system because it is a good client and there is quite a bit of work coming down the pipe from him.

 

[wannabeSE]

I am not familiar with ICFs. For typical concrete walls, the tie requirements for walls are in ACI 318-08 section 14.3.6. They may be the same for ACI 318-11.

"14.3.6 — Vertical reinforcement need not be enclosed by lateral ties if vertical reinforcement area is not greater than 0.01 times gross concrete area, or where vertical reinforcement is not required as compression reinforcement."

 

[dhoward26]

I do know about that section. But it seams a window/door Jamb is a little different criteria...or at least seams it should be.