PART 4 SHEAR LOAD
Pryout Failure Mode ( Concrete Breakout )
Calculations N b
Calculations 318-14 Chapter 17 Provision Comments for PROFIS Engineering
N b
17.4.2.2 The basic concrete breakout strength of a single anchor in tension in cracked concrete ,
N b
, shall not exceed
N ba
= k c λ a f ́c h ef
1.5
( 17.4.2.2a ) …………………………………………………………
Alternatively , for cast-in headed studs and headed bolts with 11 in . ≤ h ef ≤ 25 in ., N b shall not exceed
N b
= 16λ a f ́c h ef
5 / 3
( 17.4.2.2b )
Example : Example of k c
-values given in a mechanical anchor approval .
ICC-ESR-1917 Table 3
Design information
Effective min . embedment
Symbol Units
Effectiveness factor k uncr for uncracked concrete Effectiveness factor k uncr for cracked concrete
Example :
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-ESR-3187 Table 12
DESIGN INFORMATION Symbol Units
Effectiveness factor k uncr 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
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 k c -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 318-14 Section 17.2.6 to calculate λ a
.
PROFIS Engineering users can input an f ́c-value within the range 2500 psi ≤ f ́c ≤ 8500 psi for post-installed anchor design . The maximum f ́c-value for postinstalled anchor calculations will be limited to 8000 psi . PROFIS Engineering users can input an f ́c-value within the range 2500 psi ≤ f ́c ≤ 10,000 psi for cast-in anchor design . The maximum f ́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 f ́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
.
17.2.6 Modification factor λ a for lightweight concrete shall be taken as : Cast-in and undercut anchor concrete failure ....................... 1.0 λ Expansion and adhesive anchor concrete failure . . . . . . . . . . . . . . . . . . . . . 0.8 λ Adhesive anchor bond failure per Eq . ( 17.4.5.2 ) ...................... 0.6 λ
where λ is determined in accordance with 19.2.4 . It shall be permitted to use an alternative value of λ a where tests have been performed and evaluated in accordance with ACI 355.2 or ACI 355.4 .
17.2.7 The values 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 . Testing is required for post-installed anchors when used in concrete with f ́c greater than 8000 psi .
286 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions