2.0 SHEAR
2.3 Steel Failure Mode
Equations V cp
Equations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
V cp
= k cp
A Na ψed , Na ψ cp , Na
N ba
A Na0
17.7.3.1 Nominal pryout strength , V cp for a single anchor …….. shall not exceed ( a )……….
( a ) For a single anchor
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 )
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 ), and for adhesive anchors , N cp shall be the lesser of N a calculated by Eq . ( 17.6.5.1a ) and N cb calculated by Eq . ( 17.6.2.1a ). 17.6 . 2.1 Nominal concrete breakout strength in tension , N cb of a single anchor …….. shall be calculated by ( a )……. ( a ) For a single anchor
N cb
= A Nc ψ ed , N ψ c , N ψ cp , N
N b
( 17.6.2.1a )
A Nc0
17.6.5.1 Nominal bond strength in tension , N a of a single adhesive anchor …….. shall be calculated by ( a )………. ( a ) For a single adhesive anchor
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 a single adhesive anchor ( V cp
) as the product of k cp and the smaller of N cb calculated per Eq . ( 17.6.2.1a ) and N a calculated per Eq .
( 17.6.5.1a ). Nominal pryout strength ( N cp
) 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 , a single adhesive anchor is subjected to only a shear load . No tension load acts on the anchor ; therefore , neither nominal concrete breakout strength ( N cb
) nor nominal bond strength ( N a ) are considered as tension design parameters , but a pryout parameter “ N cp ” corresponding to the smaller of N cb calculated per Eq . ( 17.6.2.1a ) and N a calculated per Eq . ( 17.6.5.1a ) is considered .
adhesive anchor systems No tension load applied : N cb and N a
= 0 . Shear load applied , so calculate concrete pryout ( k cp
N cp
). adhesive anchor system : V cp = k cp
MIN { N cb
; N a }.
|
N a
=
A
|
Na ψ ed , Na ψ cp , Na
N ba
|
( 17.6.5.1a ) |
|
A Na0
|
|
Reference the Variables section of the PROFIS Engineering report for information on : k cp
: coefficient for pryout strength
Reference the Calculations section of the PROFIS Engineering report for more information on the following parameters :
A Na
: area of influence for anchors in tension
A Na0
: area of influence for single anchor in tension
ψ ed , Na
: tension modification factor for edge distance
ψ cp , Na
: modification factor for splitting
N ba
: basic bond strength in tension
242 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions