PROFIS ENGINEERING REPORT SHEAR LOAD
Concrete Breakout Failure Mode
Variables h a
Variables ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering
h a
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
( 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
………….…….. A Vc is the projected area of the failure surface on the side of the concrete member at its edge for a single anchor or a group of anchors . It shall be permitted to evaluate A Vc as the base of a truncated half-pyramid projected on the side face of the member where the top of the halfpyramid is given by the axis of the anchor row selected as critical . The value of ca1 shall be taken as the distance from the edge to this axis .
…………………………………….. 17.5.2.8 The modification factor for anchors located in a concrete member where h a
< 1.5c a1 , ψ h , V
, shall be calculated as
The parameter h a corresponds to the thickness of the concrete member . The member thickness is considered when calculating the shear area of influence assumed to develop at the edge of a concrete member ( A Vc
) and the shear concrete breakout modification factor for a thin concrete member ( ψ h , V
).
The geometry for A Vc assumes a projected distance down from the surface of the concrete , at the edge where concrete breakout in shear is assumed to occur , equal to the smaller of the concrete thickness ( h a
) and a projected distance defined by 1.5c a1 . The parameter c a1 corresponds to the distance from an assumed row of anchors in shear to the fixed edge where concrete breakout in shear is assumed to occur . The figure below illustrates how calculation of A Vc considers the concrete thickness ( h a
). ψ h , V
=
1.5c a1 ( 17.5.2.8 )
h a
………………………………………..
For the cast-in anchors in its portfolio , PROFIS Engineering assumes a minimum concrete thickness ( h min
) as follows : h min
= h ef + t h
+ 3 / 8 ” where
h ef
= effective embedment depth ( in ) t h
= anchor head thickness ( in ) 3 / 8 ” = assumed minimum concrete cover
MATERIAL SPECIFICATION
ASTM F1554 Headed Bolt GR . 36 , 55 , 105
ANCHOR DIAMETER ( d anchor
) ( in )
Hex Head ( in )
Heavy Hex Head ( t h
) ( in )
Square Head ( t h
) ( in )
Heavy Square Head
( t h ) ( in )
0.500 |
0.344 |
0.344 |
0.328 |
0.328 |
0.625 |
0.422 |
0.422 |
0.422 |
0.422 |
0.750 |
0.500 |
0.500 |
0.500 |
0.500 |
0.875 |
0.552 |
0.552 |
0.594 |
0.594 |
1.000 |
0.672 |
0.672 |
0.656 |
0.656 |
1.125 |
0.750 |
0.750 |
0.750 |
0.750 |
1.250 |
0.844 |
0.844 |
0.844 |
0.844 |
1.375 |
0.906 |
0.906 |
0.906 |
0.906 |
1.500 |
1.000 |
1.000 |
1.000 |
1.000 |
1.750 |
|
1.156 |
|
|
2.000 |
|
1.344 |
|
|
Minimum Base Material Thickness ( h a , min
) ( in ) h min
= h + t + 0 . 375 in ef h if h a
< 1.5c a1 : A Vc
= ( c a2 + s x
+ 1.5c a1 ) ( h a
) if h a > 1.5c a1
: A Vc = ( c a2
+ s x
+ 1.5c a1 ) ( 1.5c a1
) ψ h , V is a modification factor that is used to account for a concrete member thickness ha that is less than 1.5c a1
. The figure below illustrates how calculation of ψ h , V considers the concrete thickness ( h a ).
MATERIAL SPECIFICATION
AWD D1.1 Headed Stud
ANCHOR |
DIAMETER |
t h
( in )
|
|
( d anchor
) ( in )
|
0.500 |
0.313 |
0.625 |
0.313 |
0.750 |
0.375 |
0.875 |
0.375 |
Minimum Base Material Thickness ( h a , min
) ( in ) h min
= h + t + 0 . 375 in ef h
179 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions