Alternative Support Systems for Cantilever - National Transportation ...

and Figure 3-6. Equation 3-6 displays the equation utilized to determine the concrete breakout
strength of a single plate.
A
= V
(3-6)
Vcp
V c ψ
bp
ed,
Vψ
c,
Vψ
h,
V
AVco
b
Where
Vcbp = The nominal concrete breakout strength in shear of a single plate (lb.)
AVcp = The projected area of the failure surface for a single plate, used to
determine the shear strength (in 2 )
=3.0ca1*(3.0ca1 + lpl)
AVco = projected concrete failure area of a single anchor, for calculation of
strength in shear, if not limited by corner influences, spacing, or member
thickness (in. 2 )
= 4.5(ca1) 2 , based on an ≈35° failure cone (Figure 3-4)
The contribution of each plate to the overall torsional strength of the embedded pipe (Tcbp)
is twice the expected breakout strength (Vcbp) multiplied by the moment arm. It is twice the
expected breakout strength because as mentioned earlier, the shear strength when loaded parallel
to the edge of concrete is permitted to be twice that of the shear strength when loaded
perpendicular to the edge of concrete and Equations 3-5 and 3-6 are for loading perpendicular to
the edge of concrete.
T = 2V
nr
(3-7)
c bp
cbp
p
Where
Tcbp = The nominal torsional strength of the pedestal from concrete breakout (kip-ft)
Vcbp = The nominal concrete breakout strength in shear of plate configuration
where the plates are not acting as a group (lb.)
n = The number of torsional plates in the configuration; the plates are not acting in a
group
= The radius of the pipe (in.)
rp
3.1.2 Equivalent Side-Face Blowout Strength
Another method to determine the torsional strength of the embedded pipe and plate section
is to determine the available bearing strength of concrete for the embedded pipe and plate
section. The bearing strength was expected to be calculated similarly to the side-face blowout
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