PART 4 SHEAR LOAD
Pryout Failure Mode ( Concrete Breakout )
Calculations ψ cp , N
Calculations 318-14 Chapter 17 Provision Comments for PROFIS Engineering
ψ cp , N
17.4 . 2.7 The modification factor for post-installed anchors designed for uncracked concrete in accordance with 17.4 . 2.6 without supplementary reinforcement to control splitting , ψ cp , N
, shall be calculated as follows using the critical distance c ac as defined in 17.7.6
If c a , min ≥ 1.5c ac
, then ψ cp , N = 1.0 ( 17.4.2.7a )
If c a , min < c ac
, then ψ cp , N = c a , min
( 17.4.2.7b ) c ac but ψ cp , N determined from Eq . ( 17.4.2.7b ) shall not be taken less than 1.5h ef
/ c ac , where the critical distance c ac is defined in 17.7.6 . For all other cases , including cast-in anchors , ψ cp , N shall be taken as 1.0 .
17.4 . 2.6 For anchors located in a region of a concrete member where analysis indicates no cracking at service load levels ……………..
17.7.6 Unless determined from tension tests in accordance with ACI 355.2 or ACI 355.4 , the critical edge distance c ac shall not be taken less than : Adhesive anchors .............................................. 2h ef Undercut anchors .............................................. 2.5h ef Torque-controlled expansion anchors .............................. 4h ef Displacement-controlled expansion anchor ......................... 4h ef
Example : Example of critical edge distance requirements given in a mechanical anchor approval .
The parameter ψ cp , N is only considered when designing post-installed anchors in uncracked concrete . ψ cp , N does not need to be calculated if the smallest fixed edge distance ( c a , min ) is greater than or equal to c ac
, or if cracked concrete conditions are assumed . Testing per the ICC-ES acceptance criteria AC193 and the ACI test standard ACI 355.2 is used to derive c ac values for mechanical anchors . Testing per the ICC-ES acceptance criteria AC308 and the ACI test standard ACI 355.4 is used to derive c ac values for adhesive anchor systems . c ac values derived from this testing are provided in an ICC-ESR . ACI 318-14 Section 17.7.6 provides c ac
-values for post-installed anchors ; however , these values are only intended to be used as “ guide values ” in the absence of
c ac values derived from product-specific testing . PROFIS Engineering uses the
c ac
-value that is given in the ICC-ES evaluation report for an anchor to calculate
ψ cp , N
. The value for ψ cp , N that PROFIS Engineering calculates will be limited to
MAXIMUM { c a , min / c ac
: 1.5 hef
/ c ac }, where c a , min is the smallest fixed edge distance being modeled in the application and h ef is the effective embedment depth that has been selected for the anchor . “ ψ cp , N
” calculated for concrete breakout failure in tension is not necessarily the same as “ ψ cp , N
” calculated for concrete pryout failure in shear since the number of anchors in tension may not be the same as the number of anchors in shear . When calculating concrete breakout in tension , values for c ac should be checked against fixed edge distances relevant to anchors in tension . When calculating concrete pryout in shear , values for c ac should be checked against fixed edge distances relevant to anchors in shear . Consider : 4-anchors in tension and 6-anchors in shear .
ICC-ESR-1917 Table 3
Design information
Effective min . embedment
Min . member thickness
Critical edge distance
Symbol Units
Nominal anchor diameter ( in .) 3 / 8 1 / 2 5 / 8 3 / 4 h ef in . 1-1 / 2 2 2-3 / 4 2 3-1 / 4 3-1 / 8 4 3-1 / 4 3-3 / 4 4-3 / 4 h min in . 3-1 / 4 4 5 5 4 6 6 8 5 6 8 5-1 / 2 6 8 8 c ac in . 6 4-3 / 8 4 4-1 / 8 5-1 / 2 4-1 / 2 7-1 / 2 6 6-1 / 2 8-3 / 4 6-3 / 4 12 10 8 9
Example :
Example of critical edge distance requirements given in an adhesive anchor approval . Reference ICC-ESR-3187 Section 4.1.10.2 .
284 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions