2.0 SHEAR
2.2 Pryout Failure Mode
Calculations N b
Calculations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering 17.6.2.2.1 Basic concrete breakout strength of a single anchor in tension in cracked concrete , N b
, shall be calculated by Eq . ( 17.6.2.2.1 ) except as permitted in 17.6.2.2.3
N b
= k c λ a ƒ ́c h ef
1.5
( 17.6.2.2.1 ) where k c
= 24 for cast-in anchors and 17 for post-installed anchors . 17.6.2.2.2 k c for post-installed anchors shall be permitted to be increased based on ACI 355.2 or ACI 355.4 product-specific tests , but shall not exceed 24 .
17.6.2.2.3 For single cast-in headed studs and headed bolts with 11 in . ≤ h ef ≤ 25 in ., N b
, shall be calculated by :
N b
= 16λ a ƒ ́c h ef
5 / 3
( 17.6.2.2.3 )
Example of k c
-values given in a mechanical anchor approval . ICC-ES ESR-1917 Table 3
DESIGN INFORMATION
Effective min . embedment
Symbol
Effectiveness factor k uncr for uncracked concrete Effectiveness factor k cr for cracked concrete
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
Example of k c
-values given in an adhesive anchor system approval . ICC-ES ESR-3187 Table 12
DESIGN INFORMATION Symbol Units
Effectiveness factor for cracked concrete
Effectiveness factor for uncracked concrete
3 / 8 or # 3
1 / 2 or # 4
24
17
Nominal anchor diameter ( in .)
5 / 8 or # 5
3 / 4 or # 6 k c , cr in-lb 17 k c , uncr in-lb 24
7 / 8 or # 7
Minimum embedment h ef , min in . 2-3 / 8 2-3 / 4 3-1 / 8 3-1 / 2 3-1 / 2 4 4-1 / 2 5
Maximum embedment h ef , max in . 7-1 / 2 10 12-1 / 2 15 17-1 / 2 20 22-1 / 2 25
1 or # 8
# 9
1-1 / 4 or # 10
17.2.4.1 Modification factor λ a for lightweight concrete shall be in accordance with Table 17.2.4.1 . It shall be permitted to use an alternate value of λ a if tests are performed and evaluated in accordance with ACI 355.2 or
ACI 355.4 . Table 17.2.4.1 — Modification factor λ a for lightweight concrete
Cast-in and undercut anchor concrete failure
Case λ a
[ 1 ]
1.0 λ
The parameter N b corresponds to a calculated concrete breakout strength for a single anchor without any fixed edge or spacing influences .
PROFIS Engineering uses k c = 24 to calculate N b for cast-in anchors installed at an effective embedment depth ( h ef ) less than 11 ”, and k c
= 16 to calculate N b for cast-in anchors installed at an effective embedment depth 11 ” ≤ h ef
≤ 25 ”.
PROFIS Engineering uses the kc-value given in the ICC-ES evaluation report for an anchor to calculate N b for post-installed anchors .
PROFIS Engineering users can input a λ-value based on the properties of the lightweight concrete being used in the application . Any λ-value between 0.75 and 1.0 can be input . PROFIS Engineering uses the provisions of ACI 318-19 Table 17.2.4.1 to calculate λ a
.
PROFIS Engineering users can input an ƒ ́c-value within the range 2500 psi ≤ ƒ ́c ≤ 8500 psi for post-installed anchor design . The maximum ƒ ́c-value for post-installed anchor calculations will be limited to 8000 psi . PROFIS Engineering users can input an ƒ ́c-value within the range 2500 psi ≤ ƒ ́c ≤ 10,000 psi for cast-in
anchor design . The maximum ƒ ́c-value for cast-in anchor calculations will also equal 10,000 psi .
PROFIS Engineering permits users to input an effective embedment depth ( h ef
) value ranging between 4d anchor and 25 ” for cast-in anchors . For post-installed mechanical anchors , PROFIS Engineering permits users to input a specific h ef value that given in the ICC-ES evaluation report for the anchor . For post-installed adhesive anchors , PROFIS Engineering permits users to input an
h ef value in the range h ef , min ≤ h ef
≤ h ef , max . Reference the product approval for h ef , min and h ef , max values .
Reference the Variables section of the PROFIS Engineering report for more information on the following parameters :
k c
: coefficient for basic concrete breakout strength in tension .
λ a
: lightweight concrete modification factor . ƒ ́c : concrete compressive strength .
h ef
: effective embedment depth .
ψ c , N
: modification factor for cracked or uncracked concrete conditions .
Reference the Equations section of the PROFIS Engineering report for more information on the parameter N b
.
Expansion , screw , and adhesive anchor concrete failure Adhesive anchor bond failure per Eq . ( 17.6.5.2.1 )
0.8 λ
0.6 λ
[ 1 ] λ shall be in accordance with 19.2.4
17.3.1 The value of f ́c used for calculation purposes in this chapter shall not exceed 10,000 psi for cast-in anchors , and 8000 psi for post-installed anchors . Post-installed anchors shall not be used in concrete with a strength greater than 8000 psi without testing to verify acceptable performance .
234 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions