PART 3 TENSION LOAD
Concrete Breakout Failure Mode
Results ϕ concrete
Results ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering
ϕ concrete
17.3.3 Strength reduction factor ϕ for anchors in concrete shall be as follows when the load combinations of 5.3 are used :
( c ) Anchor governed by concrete breakout , side-face blowout , pullout , or pryout strength
( ii ) Tension loads Cast-in headed studs , headed bolts , or hooked bolts
Condition A
Condition B
0.75 0.70
Post-installed anchors with category as determined from ACI 355.2 or ACI 355.4
Category 1 |
0.75 |
0.65 |
( Low sensitivity to Installation and high reliability ) |
|
|
Category 2 |
0.65 |
0.55 |
( Medium sensitivity to Installation and medium reliability ) |
|
|
Category 3 |
0.55 |
0.45 |
( High sensitivity to Installation and lower reliability ) |
|
|
Condition A applies where supplementary reinforcement is present except for pullout and pryout strengths . Condition B applies where supplementary reinforcement is not present and for pullout and pryout strengths .
Example :
Example of a post-installed mechanical anchor strength reduction factor ( ϕ-factor ) corresponding to concrete breakout failure in tension .
ICC-ESR-1917 Table 3
DESIGN INFORMATION
Effective min . |
|
|
embedment |
h ef
|
in . |
Strength reduction 0 factor for tension , concrete failure modes , or pullout , Condition B
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
0.55 0.65
ACI 318-14 strength design provisions for concrete breakout failure in tension require calculation of a nominal concrete breakout strength ( N cb or N cbg
). The nominal strength is multiplied by one or more strength reduction factors ( ϕ-factors ) to obtain a design strength ( ϕN cb or ϕN cbg
). ϕ-factors are relevant to static and seismic load conditions .
PROFIS Engineering designates the ϕ-factor corresponding to concrete breakout failure for static load conditions “ ϕ concrete
”. When designing cast-in-place anchors , PROFIS Engineering uses the ϕ-actors given in ACI 318-14 Section 17.3.3 . The ϕ-factors in Section 17.3.3 that are given for post-installed anchors are only intended to be used as guide values in the absence of product-specific data .
Post-installed mechanical anchors can be shown compliance 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 shown compliance 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 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-ESR for the anchor . The ϕ-factors in the ICC-ESR correspond to Condition B .
PROFIS Engineering defaults to Condition B when calculating concrete breakout strength in tension . If Condition A is selected as a design parameter for either cast-in-place or post-installed anchors , PROFIS Engineering uses the Condition A ϕ-factors given in ACI 318-14 Section 17.3.3 to calculate the design concrete breakout strength in tension .
PROFIS Engineering designates the 0.75 reduction factor noted in ACI 318-14 Section 17.2.3.4.4 for seismic load conditions “ ϕ seismic
”.
Reference the Results section of the PROFIS Engineering report for more information on the following parameters :
N cb or N cbg :
Nominal concrete breakout strength in tension ϕNcb or ϕN cbg : Design concrete breakout strength in tension ϕ seismic
: Strength reduction factor for seismic tension
Example :
Example of a post-installed adhesive anchor system strength reduction factor ( ϕ-factor ) corresponding to concrete breakout failure in tension .
ICC-ESR-3187 Table 12
DESIGN INFORMATION Symbol Units
Strength reduction 0 factor for tension , concrete failure modes , or pullout , Condition B
3 / 8 or # 3
1 / 2 or # 4
Nominal Rod Diameter ( in ).
5 / 8 or # 5
3 / 4 or # 6
ϕ - 0.65
7 / 8 or # 7
1 or # 8
# 9
1 / 4 or # 10
76 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions