RC Detailing for Wall Opening Near Wall Edge
RC Detailing for Wall Opening Near Wall Edge
(OP)
I'm looking at a concrete upstand that I've been treating as a wall. It's about 1100mm tall, 200mm thick, and there are some openings of 1050x220 mm. Some of the openings are very close to a wall edge - leaving around 115mm of concrete from edge of opening to edge of wall. How would you go about detailing this? The 'standard' practice of proving half of the bars that have been broken on either side of the opening is a bit unrealistic (the wall has 2 layers of 16mm bars @ 150mm centres both ways, so would mean fitting in 2 layers of 4 bars into the 115mm). On top of this, 14.3.7 of ACI 318 dictates that two additional 16mm bars are required around the opening in a wall with 2 layers of reinforcement. On top of this there's the good practice of providing diagonal bars, but being so close to the edge of the wall means there's no space for a diagonal bar, and simply bending it to be vertical would be an additional vertical bar on top of all the vertical bars I've already mentioned! I don't know if I'm overthinking this for a 'wall' that's so short, and isn't carrying any significant load above it. Any views would be appreciated, thanks.






RE: RC Detailing for Wall Opening Near Wall Edge
Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
www.americanconcrete.com
RE: RC Detailing for Wall Opening Near Wall Edge
1) Ignore all the detailing protocols as they wont help you.
2) Keep two wall vertical bars in the edge bit.
3) Accept that the edge bit will probably crack a fair bit under shrinkage strain.
4) If this is a beam to any extent, design it as though there's no concrete above the opening at all as that concert will be useless.
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.
RE: RC Detailing for Wall Opening Near Wall Edge
I'd probably reinforce it as KootK indicated and design it as a plain concrete column to support the tributary load. I'd do everything I could to push load away from this "post" as I could. I'd also be worried about cracking at the corners so I'd bend one of the 16 mm bars as shown below:
If you actually need this to take some load then I'd either try to find some more concrete somewhere or look at more exciting ways to reinforce this.
Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
www.americanconcrete.com
RE: RC Detailing for Wall Opening Near Wall Edge