1.0 TENSION
1.2 Concrete Breakout Failure Mode
Calculations A Nc0
Calculations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
A Nc0
= 9h ef
2
17.6 . 2.1.4 A Nc0 is the projected concrete failure area of a single anchor with an edge distance of at least 1.5h ef and shall be calculated by Eq . ( 17.6.2.1.4 ).
A Nc0
= 9h ef
2
( 17.6.2.1.4 )
17.9.4 Value of h ef for a post-installed expansion , screw , or undercut post-installed anchor shall not exceed the greater of 2 / 3 of the member thickness , h a
, and the member thickness minus 4 in ., unless determined from tests in accordance with ACI 355.2 .
Example of embedment depth and concrete thickness requirements given in a mechanical anchor approval .
ICC-ES ESR-1917 Table 3
DESIGN |
|
|
|
Nominal anchor diameter ( in .) |
|
|
INFORMATION Symbol
Units
|
|
|
3 / 8 |
1 / 2 5 / 8 |
3 / 4 |
Effective min . embedment
Min . member thickness 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
Example of embedment depth and concrete thickness requirements given in an adhesive anchor system approval .
ICC-ES ESR-3187 Table 12
DESIGN INFORMATION Symbol Units
3 / 8 or # 3
1 / 2 or # 4
Nominal anchor diameter ( in .)
5 / 8 or # 5
3 / 4 or # 6
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
A Nc0 is a modification factor that accounts for the area of influence assumed to develop in concrete when a tension load is applied to a single anchor without the influence of any fixed edges . A Nc0 is calculated with the effective embedment depth of the anchor ( h ef ) input into the PROFIS Engineering file . A Nc0 is always defined as a square that has sides equal to 3.0h ef
. The length of the side in the x direction corresponds to a projected distance of 1.5h ef from the anchor in the + x and -x directions . The length of side in the y direction corresponds to a projected distance of 1.5h ef from the anchor in the + y and -y directions .
For cast-in-place anchor design , PROFIS Engineering uses the following embedment depth and concrete thickness parameters : embedment depth ( h ef )
4d a
≤ h ef ≤ 25 in d a
= nominal anchor diameter minimum concrete thickness ( h min
) h min
= h ef + t h
+ 0.375 in t h
= anchor head thickness
Values for t h are taken from product data for ASTM F1554 hex , heavy hex , square and heavy square bolts ; and from AWS D1.1 headed studs .
Post-installed mechanical anchors can be qualified for recognition under the International Building Code via testing per the ICC-ES acceptance criteria AC193 in conjunction with the ACI standard ACI 355.2 . Post-installed adhesive anchor systems can be qualified for recognition under the International Building Code via testing per the ICC-ES acceptance criteria AC308 in conjunction with the ACI standard ACI 355.4 . For post-installed anchor design , PROFIS Engineering uses the embedment depth and concrete thickness parameters derived from AC193 / ACI 355.2 or AC308 / ACI 355.4 testing , as given in the ICC-ES evaluation report ( ESR ) for the anchor .
PROFIS Engineering will not perform calculations for an anchor if the embedment depth or concrete thickness are outside the limits noted above .
The figure below illustrates how A Nc0 is calculated .
Minimum concrete thickness h min in . h ef
+ 1-1 / 4 h ef + 2d 0
A Nc0
= ( 1.5h ef + 1.5h ef
) ( 1.5h ef + 1.5h ef
)
= ( 9.0h ef
) 2
Reference the Variables section of the PROFIS Engineering report for more information on h ef
.
Reference the Equations section of the PROFIS Engineering report for more information on A Nc0
.
68 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions