PART 4 SHEAR LOAD
Pryout Failure Mode ( Concrete Breakout )
Equation A Nc0
Equation 318-14 Chapter 17 Provision Comments for PROFIS Engineering
A Nc0
= 9h ef
2
17.4 . 2.1 …….. A Nc0 is the projected concrete failure area of a single anchor with an edge distance greater than 1.5h ef .
A Nc0
= 9h ef
2
( 17.4.2.1c )
17.4 . 2.1 The nominal concrete breakout strength in tension , N cb of a single anchor or N cbg of a group of anchors , shall not exceed : ( a ) For a single anchor
N cb
= A Nc ψ ed , Na ψ c , N ψ cp , N
N b
( 17.4.2.1a )
A Nc0
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 .
( b ) For a group of anchors
N cbg
= A Nc ψ ec , N ψ ed , N ψ c , N ψ cp , N
N b
( 17.4.2.1b )
A Nc0
A Nc0
= ( 1.5h ef + 1.5h ef
) ( 1.5h ef + 1.5h ef
)
= ( 9.0h 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
.
258 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions