2.0 SHEAR
2.3 Steel Failure Mode
Equations V cpg
Equations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
V cpg
= k cp
A Na ψec1 , Na ψ ec2 , Na ψ ed , Na ψ cp , Na
N ba
A Na0
17.7.3.1 Nominal pryout strength , ………………… V cpg of an anchor group ……….. shall not exceed …..( b )……….. ( b ) For an anchor group
k cp
= 1.0 for h ef < 2.5 in . k cp
= 2.0 for h ef ≥ 2.5 in .
V cpg
= k cp
N cpg
( 17.7.3.1b )
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 ), and for adhesive anchors , N cpg shall be the lesser of N ag calculated by Eq . ( 17.6.5.1b ) and N cbg calculated by Eq . ( 17.6.2.1b ). 17.6 . 2.1 Nominal concrete breakout strength in tension , …………. N cbg of an anchor group shall be calculated by ….( b )……….. ( b ) For an anchor group
Concrete pryout is a shear failure mode that is calculated for cast-in-place anchors and post-installed anchors . ACI 318-19 Section 17.7.3.1 defines the nominal pryout strength for an adhesive anchor group ( V cpg
) as the product of k cp and the smaller of N cbg calculated per Eq . ( 17.6.2.1b ) and N ag calculated per Eq .
( 17.6.5.1b ). Nominal pryout strength ( N cpg
) is predicated on the number of anchors subjected to shear load , which may be different than the number of anchors subjected to tension load .
For the example illustrated below , four anchors are subjected to a tension load , but all six anchors are subjected to a shear load . Therefore , with respect to tension , concrete breakout ( N cbg
) and bond strength ( N ag
) are calculated for anchors 1,2,3 and 4 ; but with respect to shear , a pryout parameter “ N cpg
” corresponding to the lesser of N cbg and N ag is calculated for anchors 1,2,3,4,5 and
6 .
N cbg
= A Nc ψ ec , N ψ ed , N ψ c , N ψ cp , N
N b
( 17.6.2.1b )
A Nc0
17.6.5.1 Nominal bond strength in tension ………… N ag of an adhesive anchor group
……………. shall be calculated by ……( b )…………. ( b ) For an adhesive anchor group :
N ag
= A Na ψ ec , Na ψ ed , Na ψ cp , Na
N ba
( 17.6.5.1b )
A Na0
243 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions