2.0 SHEAR
2.2 Pryout Failure Mode
Equations A Nc0
Equations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
A Nc0
= 9h ef
2
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 )
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
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 .
N cb
= A Nc ψ ed , N ψ c , N ψ cp , N
N b
( 17.6.2.1a )
A Nc0
( b ) For an anchor group
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
)
= ( 9.0 h ef
) 2
Reference the Variables section of the PROFIS Engineering report for more information on h ef
.
Reference the Calculations section of the PROFIS Engineering report for more information on A Nc
.
210 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions