PROFIS Design Guide: US-EN Summer 2021 | Page 179

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