2.0 SHEAR
2.3 Steel Failure Mode
Calculations A Na0
Calculations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
A Na0
17.7.3.1 Nominal pryout strength , V cp for a single anchor or V cpg of an anchor group satisfying
17.5.1.3.1 , shall not exceed ( a ) or ( b ), respectively . ( a ) For a single anchor
V cp
= k cp
N cp
( 17.7.3.1a )
( b ) For an anchor group
V cpg
= k cp
N cpg
( 17.7.3.1b )
When calculating the nominal concrete pryout strength in shear ( V cp or V cpg
), the parameter A Na0 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 Na0 is calculated per ACI 318-19 Eq . ( 17.6.5.1.2a ). The parameter “ c Na
” in this equation is calculated per Eq . ( 17.6.5.1.2b ), and corresponds to an assumed projected distance on either side of the anchor in the x and y directions .
The figure below illustrates how A Na0 is calculated . 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 ).
17.7.3.1.2 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 ).
17.6.5.1 Nominal bond strength in tension , N a of a single adhesive anchor or N ag of an adhesive anchor group satisfying 17.5.1.3.1 , shall be calculated by ( a ) or ( b ), respectively . ( a ) For a single adhesive anchor
( b ) For an adhesive anchor group
|
N a
=
A
|
Na ψ ed , Na ψ cp , Na
N ba
|
( 17.6.5.1a ) |
|
A Na0
|
|
N ag
= A Na ψ ec , Na ψ ed , Na ψ cp , Na
N ba
( 17.6.5.1b )
A Na0
17.6.5.1.1 A Na is the projected influence area of a single adhesive anchor or an adhesive anchor group that is approximated as a rectilinear area that projects outward a distance c Na from the centerline of the adhesive anchor , or in the case of an adhesive anchor group , from a line through a row of adjacent adhesive anchors . A Na shall not exceed nA Na0
, where n is the number of adhesive anchors in the group that resist tension . 17.6.5.1.2 A Na0 is the projected influence area of a single adhesive anchor with an edge distance of at least c Na .
A Na0
= ( 2c Na ) 2 ( 17.6.5.1.2a ) where
A Na0
= ( c Na + c Na
) ( c Na + c Na
)
= ( 2.0c Na
) 2
Adhesive anchor systems can be qualified for recognition under the International Building Code ( IBC ) via testing per the ICC-ES acceptance criteria AC308 and the ACI standard ACI 355.4 . The parameter “ т uncr
” in Eq . ( 17.6.5.1.2b ) corresponds to the characteristic bond stress in uncracked concrete of the adhesive product selected for the PROFIS Engineering application being modeled . Values for т uncr are derived from AC308 / ACI 355.4 testing , and are shown as “ т k , uncr
” in the ICC-ES evaluation report ( ESR ) for the adhesive anchor system . The PROFIS Engineering report designates this parameter “ т k , c , uncr
”.
Reference the Variables section of the PROFIS Engineering report for more information on the parameters т k , c , uncr and d a
.
Reference the Equations section of the PROFIS Engineering report for more information on A Na0 and c Na . c Na
= 10d a т uncr ( 17 . 6 . 5 . 1 . 2b ) 1100
269 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions