Foundation reinforcement layout

[Tstruct]

What are your suggestions for steel reinforcement layout for the meeting point of curved and straight reinforcement. If the reinforcement with varying length is omitted then there would be around 2 feet gap between curved and straight bars at that meeting point. See highlighted portion in attached image.

 

[JedClampett]

I'd lay out all the bars orthogonally and let the detailer adjust the length. Bending all those bars will be a huge nuisance. And is the 3-inch spacing a typo? I'd use larger bars at wider spaces.

 

[canwesteng]

Interested to hear what others would do. In your situation, I would have omitted the curved bars entirely and used straight bars only.

If you're sold on curved bars, I would run straight bars in the N-S footing from the west edge of the footing all the way to the projected east edge of the footing, and then lap with the curved bars. It will get congested though.

 

[phamENG]

I'd do straight in the field, but use a single curved bar on each face in each layer.

 

[canwesteng]

The outer curved bar is a good idea, makes tieing the bar much easier. Otherwise a bit of pain locating all the bars perpendicular ish to the curve

 

[KootK]

Taking your existing rebar layout in the other areas as a given, I'd probably do something like I've shown in the sketch below with the bars placed in an additional reinforcing layer. That will reduce their flexural effectiveness a bit but, unless I misunderstand the situation, the rebar in the yellow highlighted area won't be doing much anyhow beyond temperature and shrinkage crack control.

 

[jayrod12]

Top and bottom mats at 3" o/c. That's a shit ton of reinforcing. We'd have made it deeper and cut the reinforcing in half. And probably considered using larger bars to space them out further as well. But where I am, concrete is cheaper than rod-buster wages.

 

[Tstruct]

1. This retaining wall foundation is designed for 5/8@3"c/c (main direction), distribution should have been shrinkage and temp reinforcement only. However, due to layout of retaining walls of this specific area distribution bars for one wall becomes main for the other. Therefore I had to avoid temp and shrinkage r/f and provide main r/f in all directions for this specific area.

2. Here in my office the practice is not to use larger diameter bar before exhausting smaller one's capacity i.e upto 3" spacing. Also clients and/or contractors object on using larger diameter for smaller structures. Of course it is a lay man's approach. But no one would have larger diameter bars in stock when the nature of structures in question aren't big.

 

[WesternJeb]

Tstruct, interesting philosophies. My office usually specs out larger bars because that is what the contractor prefers; they would rather lift and set 15 #7 bars versus 30 #5 bars. It ends up saving them labor cost, and in my mind it helps consolidate the concrete better.

 

[phamENG]

Note that Tstruct is in Pakistan. Not sure how things are now, but I had a Pakistani professor in school. When teaching us about engineering economy, he told us how, when he was first getting started, 100lbs of steel was more expensive than an entire crew of iron workers working for a week. So labor costs weren't really a consideration, just minimizing material and working within the confines of very challenging supply constraints. I'm sure it's not so extreme now (assuming the prof wasn't using a bit of hyperbole to begin with), but I imagine those design philosophies are still pretty widespread.

I agree, though, that 3" is getting really tight and the crew placing the concrete better bring their A game.

 

[WesternJeb]

Thanks for the disclaimer, phamEng! That makes a little more sense.

 

[Tstruct]

Yes, labor is still very cheap here as compared to steel. Today steel rate is 950 USD per metric ton. Whereas you can find a laborer for whole day for as low as 7-8 USD.