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V cb
=
|
A vc ψed , V ψ c , y ψ h , V
V b
A vc0
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17.5 . 2.1 The nominal concrete breakout strength in shear , V cb of a single anchor or V cbg of a group of anchors , shall not exceed :
( a ) For shear force perpendicular to the edge on a single anchor
V cb
=
A vc ψed , V ψ c , y ψ h , V
V b
( 17.5.2.1a )
A vc0
|
ACI 318-14 provisions for concrete breakout failure in shear include two equations for calculating the “ nominal concrete breakout strength ” in shear :
• Eq . ( 17.5.2.1a ) for calculating the nominal concrete breakout strength for a single anchor in shear ( V cb
)
• Eq . ( 17.5.2.1b ) for calculating the nominal concrete breakout strength for a group of anchors in shear ( V cbg
)
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( b ) For shear force perpendicular to the edge on a group of anchors
V cbg
= A vc ψ ec , V ψ ed , V ψ c , V ψ h , V
V b
( 17.5.2.1b )
A vc0
( c ) For shear force parallel to an edge V cb or V cbg shall be permitted to be twice the value of the shear force determined from Eq . ( 17.5.2.1a ) or ( 17.5.2.1b ), respectively , with the shear force assumed to act perpendicular to the edge and with ψ ed , V taken equal to 1.0 .
( d ) For anchors located at a corner , the limiting nominal concrete breakout strength shall be determined for each edge , and the minimum value shall be used .
PROFIS Engineering includes an additional modification factor ( ψ parallel , V
) in Eq . ( 17.5.2.1a ) and Eq .
( 17.5.2.1b ).
PROFIS Engineering calculations for V cb
:
V cb
=
A Vc ψed , V ψ c , V ψ h , V ψ parallel , V
V b
A Vc0
PROFIS Engineering calculations for shear load acting at a corner .
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Concrete breakout in shear is calculated for shear load acting towards ( i . e . perpendicular to ) a fixed edge . If shear load acts parallel to a fixed edge , Section 17.5.2.1 ( c ) requires V cb or V cbg to be calculated as if the shear load acts towards the fixed edge , and the value calculated for V cb or V cbg to be doubled . The PROFIS Engineering parameter that is designated in the report as “ ψ parallel , V
” indicates whether the software is calculating concrete breakout for shear load acting towards a fixed edge ( ψ parallel , V
= 1.0 ) or parallel to a fixed edge ( ψ parallel , V
= 2.0 ).
If a shear load acts at an angle with respect to two fixed edges , Section 17.5.2.1 ( d ) requires V cb or V cbg to be calculated with respect to each fixed edge . The calculated value for V cb or V cbg is checked against the component of the shear load that acts towards each fixed edge . PROFIS Engineering calculates V cb or V cbg for load acting towards each fixed edge as well as load acting parallel to each fixed edge . The software then checks the calculated V cb or V cbg value for each load condition ( towards the edge and parallel to the edge ) against the resultant shear load rather than the shear load component acting on each edge . This is a conservative design assumption .
Reference the Calculations section of the PROFIS Engineering report for more information on the following parameters :
A Vc
:
A Vc0
:
ψ ed , V
:
ψ h , V
:
V b
:
Area of influence for anchors in shear
Area of influence for single anchor in shear
Shear modification factor for edge distance
Modification factor for thin slabs
Basic concrete breakout strength in shear
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Reference the Variables section of the PROFIS Engineering report for information on : |
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ψ c , V
:
ψ parallel , V
:
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Modification factor for cracked concrete
Modification factor for shear parallel to a fixed edge
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