Temperature and Shrinkage Reinforcement in strip footing

[gijaja]

In a strip footing of a cantilever retaining wall, is one
layer of Temp and Shrinkage in the long direction sufficient? Are there any requirements for T&S in both the top and bottom?

 

[rscassar]

T&S (temperature and shrinkage) reinforcement is required for the total cross section. So if you have a cantilever retaining wall footing 10-12" thick, I generally provide 1 layer of #5 bars at 12". This makes up the required 0.2% which constitutes minor crack control.

See attached.

 

[msquared48]

Yes. I typically provide one layer bottom at the toe, just over the toe steel, and one layer top in the heel, just under the heel steel.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[tumbleleaves]

It isn't exempted in the ACI 318, perhaps slab on grade or somewhere else? I don't recall putting in that much steel for T&S. The temperature isn't an issue since the footing is always buried, so it's only shrinkage.

Albeit I admit its been years since I designed a concrete retaining wall, and 90% of the time I'd just use a State standard plans. I only designed walls when there was an anomaly, property line, unusual soil condition, etc.

Also the cost of the steel is usually not an issue, so I recommend put it in if you have any doubt.

 

[pwht1]

Do any of you provide joints in the footing that match the wall joints, ie 6-8m centres? And do you have the footing pours sequenced so alternate strips are poured?

 

[rscassar]

Depends if the footing slab is visible. If the slab is not visible then I just specify a continuous run of footing without any joints. If the footing slab is visible (say it also serves as a pavement) then I will specify that the slab joints match the wall joints.