Yes, lateral force on a wall would produce tensile stress on one side of the
wall and compression stress on the other. Concrete is very strong in
compression but very weak in tension. To compensate for the weakness, steel
is added to the concrete.
Steel Reinforcement
The amount and placement of the steel reinforcements depends on the magnitude
of the load and other factors. However, there are some guidelines that we
can use to preliminarily size and place steel in walls we propose.
But first, we need to know something about reinforcing steel or rebar.
It is mild, 60 grade (Minimum yield strength of 60,000 psi) billet steel,
conforming to ASTM615. You can see that it is ribbed (deformed) for good
adhesion. It is available in a range of sizes indicated by numbers that
represent the eighths of an inch of diameter. For example, the smallest
rebar is #3 or 3/8" diameter. For most landscape applications #3
and #4 will be specified but very large diameters are available too.
You can see in the image that rebar rusts unless it is specified with galvanized
or teflon coating. The small amount shown in the
image would be acceptable but the steel should be generally free of oils and rust.
Rebar is placed vertically and horizontally within cast-in-place
elements. It is held at least 2 inches from the surfaces of above ground,
wall edges and at least 3" from below ground concrete surfaces. This
is to reduce the rusting of concrete inside the concrete that occurs when water
migrates into the concrete. 
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