|
ψ cp , N
= MAX
|
c a , min , 1.5h ef ≤1 . 0
c ac
c ac
|
17.6.2.6.1 Modification factor for post-installed anchors designed for uncracked concrete in accordance with 17.6.2.5 without supplementary reinforcement to control splitting , ψ cp , N
, shall be determined by ( a ) or ( b ) using the critical distance c ac as defined in 17.9.5 .
( a ) If c a , min ≥ c ac
, then ψ cp , N = 1.0 ( 17.6.2.6.1a )
( b ) If c a , min < c ac
, then ψ cp , N =
c a , min
c ac
≥
1.5h ef ( 17 . 6 . 2 . 6 . 1b )
c ac
|
ψ cp , N is a modification factor that considers splitting failure when calculating the nominal concrete breakout strength in tension ( N cb or N cbg ) for a post-installed anchor . The parameter ψ cp , N is only considered when designing post-installed mechanical or adhesive anchors installed in uncracked concrete . Splitting failure will typically not occur for cast-in-place anchors ; therefore , ψ cp , N is always shown equal to 1.0 in PROFIS Engineering when modeling cast-in-place anchors . Likewise , since splitting failure is only considered relevant to uncracked concrete conditions , ψ cp , N is always shown equal to 1.0 in PROFIS Engineering when modeling cast-in-place or post-installed anchors for cracked concrete conditions . |
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17.6.2.6.2 For all other cases , including cast-in anchors , ψ cp , N shall be taken as 1.0 .
17.6 . 2 . 5.1 …….. For anchors located in a region of a concrete member where analysis indicates no cracking at service load levels ……………..
17.9.5 Critical edge distance c ac shall be in accordance with Table 17.9.5 unless determined from tension tests in accordance with ACI 355.2 or ACI 355.4 .
Table 17.9.5 – Critical edge distance
Post-installed anchor type
Torque-controlled
Displacement-controlled
Screw
Undercut
Adhesive
Critical edge distance c ac
4 h ef
4 h ef
4 h ef
2.5 h ef
Example of critical edge distance requirements given in a mechanical anchor approval .
ICC-ES ESR-1917 Table 3
Effective min . embedment
Min . member thickness
Critical edge distance
2 h ef
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
c ac in . 6 4-3 / 8 4 4-1 / 8 5-1 / 2 4-1 / 2 7-1 / 2 6 6-1 / 2 8-3 / 4 6-3 / 4 12 10 8 9
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Splitting failure is influenced by the distance of an anchor from a fixed edge “ in a region of a concrete member where analysis indicates no cracking at service load levels ”. The parameter c ac that is used to calculate ψ cp , N is defined in ACI 318 as the “ critical edge distance required to develop the basic strength as controlled by concrete breakout or bond of a post-installed anchor in tension in uncracked concrete without supplementary reinforcement to control splitting .”
ψ cp , N will be shown equal to 1.0 in PROFIS Engineering if the smallest fixed edge distance ( c a , min
) is greater than or equal to c ac
. Testing per the ICC-ES acceptance criteria AC193 and the ACI test standard ACI 355.2 is used to derive c a c values for mechanical anchors . Testing per the ICC-ES acceptance criteria AC308 and the ACI test standard ACI 355.4 is used to derive c ac values for adhesive anchor systems . c ac values derived from this testing are provided in an ICC-ES evaluation report ( ESR ). ACI 318-19 Section 17.9.5 provides c ac
-values for post-installed anchors ; however , these values are only intended to be used as “ guide values ” in the absence of c ac values derived from product-specific testing . PROFIS Engineering uses the c ac
-value that is given in the ICC-ES evaluation report for an anchor to calculate ψ cp , N .
The value for ψ cp , N that PROFIS Engineering calculates will be limited to MAXIMUM { c a , min
/ c ac : 1.5 hef
/ c ac
} where c a , min is the smallest fixed edge distance less than c ac and h ef is the effective embedment depth that has been selected for the anchor being modeled .
Reference the Variables section of the PROFIS Engineering report for more information on the following parameters :
c a , min
: the smallest fixed edge distance being modeled .
c ac
: value derived from testing per AC193 / ACI 355.2 or AC308 / ACI 355.4 for the anchor being modeled . h ef
: effective embedment depth that has been selected for the anchor being modeled .
Reference the Equations section of the PROFIS Engineering report for more information on the parameter ψ cp , N
.
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Example of critical edge distance requirements given in an adhesive anchor approval . |
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ICC-ES ESR-3187 Table 12 |
DESIGN INFORMATION |
Symbol |
Units |
3 / 8 or # 3 |
1 / 2 or # 4 |
Nominal Rod Diameter ( in ).
5 / 8 or # 5
3 / 4 or # 6
7 / 8 or # 7
1 or # 8
|
# 9 |
1-14 or # 10 |
Critical edge distance splitting ( for uncracked concrete ) |
c ac
- See Section 4.1.10.2 of this report .
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