### Concrete Cutting Sawing Abington MA Mass Massachusetts

*“We
Specialize in Cutting Doorways and Windows in Concrete Foundations”*

**Are You in ****Abington Massachusetts****? Do You
Need Concrete Cutting?**

**We Are Your Local
Concrete Cutter**

**Call ****781-519-2456**

**We Service Abington
MA and all surrounding Cities & Towns**

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Concrete
cutting and sawing as an extended toe, as is frequently done-with considerable
economy and advantage, even that toe must be designed to withstand transverse
bending at the concrete wall line, and also shearing at that point. The
application of these principles can best be understood by an illustration. Assume
that it is required to design a concrete retaining concrete wall to withstand
an ordinary earthwork pressure of 20 feet, the earth being level on top. We are
at once confronted with the determination of the actual lateral pressure of the
earthwork. Unfortunately, this is an exceedingly uncertain quantity, depending
upon the nature of the soil, upon its angle of repose, and particularly upon
its condition whether wet or dry. The angle of repose is the largest angle with
the horizontal at which the material will stand without sliding down. A
moment's consideration will show that this angle depends very largely on the
condition of the material, whether wet or dry, etc. On this account any great
refinement in these calculations is utterly useless. Assuming that the back
face of the concrete wall is vertical, or practically so; that the upper
surface of the earth is horizontal; and that the angle of repose of the
material is 30°, the total pressure of the concrete wall equals 1 w 10-, in
which h is the total height of the concrete wall, and w is the weight per
unit-volume of the earth. If the angle of repose is steeper than this, the
pressure will be less. If the angle of repose is less than this, the fraction
will be larger, but the unit-weight of the material will probably be smaller.
Assuming the weight at the somewhat excessive figure of 96 pounds per cubic
foot, we can then say, as an ordinary rule, that the total pressure of the
earth on a vertical strip of the concrete wall one foot wide will equal 16 h2,
in which it is the height of the concrete wall in feet.

The average pressure,
therefore, equals 16 It; and the maximum pressure at a depth of h feet equals
32 It. Applying this figure to our numerical example, we have a total pressure
on a vertical strip one foot wide, of 16 >< 202 = 6,400 pounds. The
pressure at a depth of 20 feet equals 32 X 20 = 640 pounds. It is usual to
compute the thickness and reinforcement of a strip one foot wide running
horizontally between two concrete buttresses. Practically the strip at the
bottom is very strongly reinforced by the base- plate, which runs at right
angles to it; but if we design a strip at the bottom of the concrete wall
without allowing for its support from the base plate, and then design all the
strips toward the top of the concrete wall in the same proportion, the upper
strips will have their proper design, while the lower strip merely has an
excess of strength. We shall assume, in this case, that the concrete buttresses
are spaced 15 feet center to center. Then the load on a horizontal strip of
face-plate 12 inches high, 15 feet long, and 19 feet 6 inches from the top,
will be 15 >< 19.5 X 32, or 9,360 pounds. Multiplying this by 4, we have
an ultimate load of 37,440 pounds. The span in inches equals 180. Then 37,440 x
180 equals 842,400 inch-pounds. Placing this equal to 397 bd2, in which b = 12
inches, we find that d2 = 176.8, and d = 13.3 inches. At one-half the height of
the concrete wall, the moment will equal one-half of the above, and the
required thickness d would be 9.4 inches. The actual thickness at the bottom,
including that required outside of the reinforcement, would therefore make the
thickness of the concrete wall about 16 inches at the bottom. At one-half the
height, the thickness must be about 12 inches. Using a uniform taper, this
would mean a thickness of 8 inches at the top. The reinforcement at the bottom
would equal .0084 X 13.3 = .112 square inch of metal per inch of height. Such
reinforcement could be obtained by using finch bars spaced 5 inches apart.

**Are You in ****Abington Massachusetts****? Do You
Need Concrete Cutting?**

**We Are Your Local
Concrete Cutter**

**Call ****781-519-2456**

**We Service Abington
MA and all surrounding Cities & Towns**