2.0 SHEAR
2.3 Steel Failure Mode
Results V cp
Results ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
V cp
17.7.3.1 Nominal pryout strength , V cp for a single anchor …….. shall not exceed ( a )……….
( a ) For a single anchor
V cp
= k cp
N cp
( 17.7.3.1a ) k cp
= 1.0 for h ef < 2.5 in . k cp
= 2.0 for h ef
≥ 2.5 in .
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
When designing adhesive anchors , ACI 318-19 Section 17.7.3.1.1 defines the nominal pryout strength for a single anchor ( V cp
) as the product of k cp and the smaller of ( N cb ) and the nominal bond strength for a single anchor ( N a
).
The bond strength parameter ( N a
) for pryout failure in shear is calculated per ACI 318-19 Eq . ( 17.6.5.1a ), but predicated on the number of anchors subjected to shear load , which may be different than the number of anchors subjected to tension load . Note that ( 17.7.3.1a ) denotes the “ concrete pryout strength ” parameter “ N cp
” to distinguish it from the bond strength parameter “ N a
”.
For the example illustrated below , a single anchor is subjected to only a shear load . No tension load acts on the anchor ; therefore , nominal bond strength in tension ( N a
) is not calculated , but a pryout parameter “ N cp ” with a bond strength parameter N a calculated per Eq . ( 17.6.5.1a ) is considered .
adhesive anchor systems No tension load applied : N a
= 0 . Shear load applied , so calculate concrete pryout ( k cp
N a
). adhesive anchor system : V cp = k cp
MIN { N cb
; N a }.
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
|
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 concrete breakout strength in tension
277 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions