2.0 SHEAR
2.2 Pryout Failure Mode
Calculations A Nc0
Calculations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
A Nc0
17.7.3.1 Nominal pryout strength , V cp for a single anchor or V cpg of an anchor group satisfying
17.5.1.3.1 , shall not exceed ( a ) or ( b ), respectively . ( a ) For a single anchor
( b ) For an anchor group
where
k cp
= 1.0 for h ef < 2.5 in . k cp
= 2.0 for h ef ≥ 2.5 in .
V cp
= k cp
N cp
( 17.7.3.1a )
V cpg
= k cp
N cpg
( 17.7.3.1b )
When calculating the nominal concrete pryout strength in shear ( V cp or V cpg
), the parameter A Nc0 is a modification factor that accounts for the area of influence assumed to develop in concrete when a shear load applied to a single anchor without the influence of any fixed edges creates a prying ( i . e . tension ) action on the anchor . A Nc0 is calculated with the effective embedment depth of the anchor
( h ef ) input into the PROFIS Engineering model . The geometry for A Nc0 is defined by a projected distance of 1.5h ef from the anchor in the x and y directions .
The figure below illustrates how A Nc0 is calculated .
17.7.3.1.1 For cast-in anchors and post-installed expansion , screw , and undercut anchors , N cp shall be taken as N cb calculated by Eq . ( 17.6 . 2.1a ) …………………..
17.7.3.1.2 For cast-in anchors and post-installed expansion , screw , and undercut anchors , N cpg shall be taken as N cbg calculated by Eq . ( 17.6 . 2.1b ) …………………… 17.6 . 2.1 Nominal concrete breakout strength in tension , N cb of a single anchor or N cbg of an anchor group satisfying 17.5.1.3.1 , shall be calculated by ( a ) or ( b ), respectively : ( a ) For a single anchor
( b ) For an anchor group
N cb
= A Nc ψ ed , N ψ c , N ψ cp , N
N b
( 17.6.2.1a )
A Nc0
N cbg
= A Nc ψ ec , N ψ ed , N ψ c , N ψ cp , N
N b
( 17.6.2.1b )
A Nc0
………………………………………….
A Nc0
= ( 1.5h ef + 1.5h ef
) ( 1.5h ef + 1.5h ef
)
= ( 9.0h ef
) 2
For cast-in-place anchors , PROFIS Engineering permits users to input h ef values ranging between 4 danchor and 25 ”. Cast-in anchors : 4 danchor
≤ hef ≤ 25 ”.
For post-installed mechanical anchors , PROFIS Engineering permits users to input specific h ef values that are relative to a specific diameter as given in the ICC-ES evaluation report for the anchor . Post-installed mechanical anchors : reference product approval .
17.6.2.1.1 A Nc is the projected concrete failure area of a single anchor or of an anchor group that is approximated as the base of the rectilinear geometrical shape that results from projecting the failure surface outward 1.5h ef from the centerlines of the anchor , or in the case of an anchor group , from a line through a row of adjacent anchors . A Nc shall not exceed nA Nc0 , where n is the number of anchors in the group that resist tension .
For post-installed adhesive anchors , PROFIS Engineering permits users to input a range of h ef values that are relative to a specific diameter as given in the ICC-ES evaluation report for the anchor . Post-installed adhesive anchors : h ef , min
≤ h ef ≤ h ef , max
. Reference the product approval for h ef , min and h ef , max values .
17.6 . 2.1.4 A Nc0 is the projected concrete failure area of a single anchor with an edge distance of at least 1.5h ef and shall be calculated by Eq . ( 17.6.2.1.4 ).
A Nc0
= 9h ef
2
( 17.6.2.1.4 )
Reference the Variables section of the PROFIS Engineering report for more information on h ef
.
Reference the Equations section of the PROFIS Engineering report for more information on A Nc
.
228 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions