PART 4 SHEAR LOAD
Pryout Failure Mode ( Pryout Bond )
Results V cp
Results 318-14 Chapter 17 Provision Comments for PROFIS Engineering
V cp
17.5.3.1 The nominal pryout strength , V cp for a single anchor …….. shall not exceed :
( a ) For a single anchor
V cp
= k cp
N cp
( 17.5.3.1a )
For cast-in , expansion , and undercut anchors , N cp shall be taken as Ncb determined from Eq .
( 17.4.2.1a ), and for adhesive anchors , N cp shall be the lesser of N a determined from Eq . ( 17.4.5.1a ) and N cb determined from Eq . ( 17.4.2.1a ) ………………………………………………………
17.4 . 2.1 The nominal concrete breakout strength in tension , N cb of a single anchor …….. 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 designing adhesive anchors , ACI 318-14 Section 17.5.3.1 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 318-14 Eq . ( 17.4.5.1a ), 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 ( 17.5.3.1a ) 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
” corresponding to N a calculated per Eq . ( 17.4.5.1a ) is calculated . adhesive anchor systems No tension load applied : N cb
= 0 . Shear load applied , so calculate concrete pryout ( k cp
N cp
). adhesive anchor system : V cp = k cp
MIN { N cb
; N a }.
17.4.5.1 The nominal bond strength in tension , N a of a single adhesive anchor …….. shall not exceed : ( a ) For a single adhesive anchor
N a
= A Na ψ ed , Na ψ cp , Na
N ba
( 17.4.5.1a )
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
245 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions