Is Temp. & Shrinkage Reinf. Required in Both Directions?
Is Temp. & Shrinkage Reinf. Required in Both Directions?
(OP)
I am designing a footing where Temperature and Shrinkage steel controls.
If say #5 @ 12" o.c. is required do I need to provide this steel in both directions or just one?
Thanks!!
If say #5 @ 12" o.c. is required do I need to provide this steel in both directions or just one?
Thanks!!





RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
If it is a continuous footing, then many times the temp/shrinkage is required down the length of the footing, but not necessarily across the footing width as this might be fairly short and usually transverse bars are required only when the cross-bending moment requires it.
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
More like a mass/arch concrete condition.
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
It drives me crazy when an engineer or architect just require longitudinal bars and expects the contractor to just lay them on concrete brick. The first thing that happens when you pour concrete is the bars will roll off the bricks into the sand!
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
Dik
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
Since you have a footing with stable temperatures and moisture, the real value of transverse steel is the constructability. Widely spaced transverse steel will keep the the longitudinal steel in a position where it will function. If you determine that longitudinal steel is not required for this project, the question of transverse steel is moot.
Often on
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
The footing cannot be proportion as plain, but if I increase the thickness it could be.
Which brings up the question: If a strip footing only has rebar in one direction then it does not meet the "reinforced concrete" requirments and is therefore considered "plain". Then what is the purpose of the longitudinal rebar? ...just for good measure?
Should there be a concern for some type of crack control in plain concrete? Both footings and piers.
For example: What if you have a very large pier, say 36"x36"x48"high (classified as a pedestal in ACI) on top of a footing. Plain concrete works for stresses, but using 1/2% of the gross Area for vertical steel seems excessive.
What should you do?
Thanks!!!
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
I think many engineers view section 10.5.4 of ACI 318 as requiring temp/shrink reinforcing per 7.12.
In many cases, a wall footing, in the direction along the wall, does not have any significant bending moments, especially if the wall is very stiff. But for simple common sense in tying the bottom of the structure together with some reinforcing, section 7.12 is typically used.
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
Dik
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
15.10.4 does express the 7.12.2 requirement for mat foundations, (says nothing about strip/wall footings).
15.8.2.2, Minimum vertical reinforcement is specified in wall/footing in 14.3.2.
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
-mdmiller
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
But if you look at the practice of many engineers, and look at the way many software products are written, the 0.0018Ag is used. Just sayin'...
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
RISA Foot seems to use the 7.12 provision in all their footings and I seem to remember challenging them on this at one point.
I have rarely (actually never) seen wall footings without at least a couple of bars. In my book it is good practice to tie it together longitudinally. But you are technically correct that 318 doesn't directly mandate it.
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
mdmiller,
ACI 318-22.8: plain concrete pedestals are permitted with a couple conditions. One of which is: unsupported height / least lateral dimension < 3
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?
RE: Is Temp. & Shrinkage Reinf. Required in Both Directions?