Alternative Support Systems for Cantilever - National Transportation ...

Vbfp
l e
tfp
bfp
f’c
ca1
= the basic concrete breakout strength in shear of one side of a flexural plate in
cracked concrete (lb.)
= the equivalent bearing length of the annular plate, taken conservatively as 1/8 of
the circumference of the centerline of the plate (in.)
= the thickness of the annular plate (in.)
= the bearing width of the annular plate (in.)
= specified compressive strength of concrete (psi)
= the edge distance, taken from the center of the width of the plate to the nearest
concrete edge (in.)
Figure 3-11. The tensile and compressive forces seen as shears acting parallel to an edge
Once the basic concrete breakout strength of one plate bearing area has been determined,
then the total shear breakout capacity can be determined using Equation 3-12. Equations 3-11
and 3-12 are used to determine the shear strength perpendicular to an edge. To determine the
shear strength parallel to an edge, the perpendicular shear strengths obtained need to be doubled.
See Figure 3-12 for a visual representation of the values in Equations 3-11 and 3-12.
A
= V
(3-12)
Vcp
V c ψ
bfp
ed,
Vψ
c,
Vψ
h,
V
AVco
Where
Vcbfp
AVcfp
Vt
bfp
= The nominal concrete breakout strength in shear of plate configuration
where the plate bearing areas are not acting as a group (lb.)
= The projected area of the failure surface for a single bearing location on the
plate, used to determine the shear strength (in 2 )
=(3.0ca1+ le)*(3.0ca1 + tfp)
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)
Vc
35