|
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 cac 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 . Since ACI 318 anchoring-to-concrete provisions do not specifically consider concrete splitting as a failure mode , splitting is addressed through the
ψ cp , N modification factor . 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 , the parameter ψ cp , N is not considered in PROFIS Engineering when modeling cast-inplace anchors .
|
|
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 cac 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
Critical edge distance c ac
4 h ef
4 h ef
4 h ef
|
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 does not need to be calculated if the smallest fixed edge distance ( c a , min ) is greater than or equal to c ac
, or if cracked concrete conditions are assumed . Testing per the ICC-ES acceptance criteria AC193 and the ACI test standard ACI 355.2 is used to derive c ac 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
.
|