2.0 SHEAR
2.1 Concrete Breakout Failure Mode
Results ϕ concrete
Results ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
ϕ concrete
17.5.3 Strength reduction factor ϕ for anchors in concrete shall be in accordance with Tables ……… …….. 17.5.3 ( b )…………………
Table 17.5.3 ( b ) — Anchor strength governed by concrete breakout , bond , and side-face blowout
Supplementary reinforcement
Supplementary reinforcement present
Supplementary reinforcement not present
Type of anchor installation
Cast-in anchors
Postinstalled anchors
Cast-in anchors
Postinstalled anchors
Anchor
Category [ 1 ] from ACI 355.2 or ACI 355.4
Not applicable
Strength reduction factor ϕ
Tension ( concrete breakout , bond , or side-face blowout )
0.75
1 0.75 2 0.65 3 0.55
Not applicable
0.70
1 0.65 2 0.55 3 0.45
Shear ( concrete breakout )
Example of a post-installed mechanical anchor strength reduction factor ( ϕ-factor ) corresponding to concrete breakout failure in shear . ICC-ES ESR-1917 Table 3
DESIGN INFORMATION
Effective min . |
|
|
embedment |
h ef
|
in . |
Strength reduction ϕ factor for shear , concrete failure modes , Condition B
0.75
0.70
Symbol Units Nominal anchor diameter ( in .)
3 / 8 1 / 2 5 / 8 3 / 4 1-1 / 2 2 2-3 / 4 2 3-1 / 4 3-1 / 8 4 3-1 / 4 3-3 / 4 4-3 / 4
0.70
ACI 318-19 strength design provisions for concrete breakout failure in shear require calculation of a nominal concrete breakout strength ( V cb or V cbg
). The nominal strength is multiplied by a strength reduction factor ( ϕ-factor ) to obtain a design strength ( ϕV cb or ϕV cbg ). Only one ϕ-factor is applied to V cb or V cbg
. The 0.75 seismic strength reduction factor required per Section 17.10.5.4 is only relevant to tension calculations , and is therefore not applied to V cb or V cbg when the anchorage is being designed for seismic shear load conditions .
PROFIS Engineering designates the ϕ-factor corresponding to concrete breakout failure for shear load conditions “ ϕ concrete
”. When designing cast-in-place anchors , PROFIS Engineering uses the ϕ-factors given in ACI 318-19 Table 17.5.3 ( b ). The ϕ-factors in Table 17.5.3 ( b ) are only intended to be used as guide values for postinstalled anchors in the absence of product-specific data .
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 . When “ Condition B ” in PROFIS Engineering is selected as a post-installed anchor design parameter , PROFIS Engineering uses the ϕ-factors derived from AC193 / ACI 355.2 or AC308 / ACI 355.4 testing , as given in the ICC-ES evaluation report ( ESR ) for the anchor . The ϕ-factors in the ESR correspond to the condition “ supplementary reinforcement not present ” noted in Table 17.5.3 ( b ).
PROFIS Engineering defaults to the assumption “ supplementary reinforcement not present ” when calculating concrete breakout strength in shear . If “ Condition A ” in PROFIS Engineering is selected as a design parameter for either cast-inplace or post-installed anchors , PROFIS Engineering uses the “ supplementary reinforcement present ” ϕ-factor given in Table 17.5.3 ( b ) to calculate the design concrete breakout strength in shear .
Reference the Results section of the PROFIS Engineering report for more information on the following parameters :
V cb or V cbg : nominal concrete breakout strength in shear . ϕV cb or ϕV cbg : design concrete breakout strength in shear .
Example of a post-installed adhesive anchor system strength reduction factor ( ϕ-factor ) corresponding to concrete breakout failure in shear . ICC-ES ESR-3187 Table 12
DESIGN INFORMATION Symbol Units
Strength reduction factor for shear , concrete failure modes , Condition B
3 / 8 or # 3
1 / 2 or # 4
Nominal rod diameter ( in ).
5 / 8 or # 5
3 / 4 or # 6
ϕ - 0.70
7 / 8 or # 7
1 or # 8
# 9
1 / 4 or # 10
201 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions