1.0 TENSION
1.3 Pullout Failure Mode
Equations N pn
Equations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering cast-in anchors
N pn
= ψ c , p
N p
17.6.3 Pullout strength of a single cast-in anchor , or a single post-installed expansion , screw , or undercut anchor in tension , N pn
.
17.6.3.1 Nominal pullout strength of a single cast-in anchor , or a single post-installed expansion , screw , or undercut anchor in tension , N pn
, shall be calculated by : where ψ c , P is given in 17.6.3.3 . 17.6.3.2 Basic single anchor pullout strength , N p
.
N pn
= ψ c , p
N p
( 17.6.3.1 )
17.6.3.2.1 For post-installed expansion , screw or undercut anchors , the values of N p shall be based on the 5 percent fractile of results of tests performed and evaluated according to ACI 355.2 . It is not permissible to calculate the pullout strength in tension for such anchors .
17.6.3.2.2 For single anchors , it shall be permitted to evaluate the pullout strength in tension ,
N p
, for use in Eq . ( 17.6.3.1 ) in accordance with ( a ) or ( b ). Alternatively , it shall be permitted to use values of N p based on the 5 percent fractile of tests performed and evaluated in the same manner as the ACI 355.2 . procedures but without benefit of friction .
( a ) For cast-in headed studs and headed bolts , N p shall be calculated by :
N p
= 8A brg ƒ ́c ( 17.6.3.2.2a )
( b ) For J- or L-bolts , N p shall be calculated by :
N p
= 0.9ƒ ́c e h d a
( 17.6.3.2.2b ) where 3d a ≤ e h
≤ 4.5d a .
Nominal pullout strength ( N pn
) is a possible tension failure mode for cast-in anchors and post-installed mechanical anchors . Generally speaking , bond failure is considered for adhesive anchor systems in lieu of pullout failure ; however , the Hilti adhesive anchor system “ HIT-HY 200 ” includes a proprietary anchor element known as a HIT-Z threaded rod , for which a nominal pullout strength is calculated in lieu of a nominal bond strength .
PROFIS Engineering calculates the nominal pullout strength ( N pn
) for the cast-in anchors in its portfolio using Eq . ( 17.4.3.1 ). The PROFIS Engineering cast-in anchor portfolio includes the following anchors :
• AWS D1.1 Type B headed studs ( 1 / 2 ” — 7 / 8 ” nominal diameter )
• ASTM F1554 hex head bolt , Gr . 36 , Gr . 55 , Gr . 105 ( 1 / 2 ” — 1-1 / 2 ” nominal diameter )
• ASTM F1554 heavy hex head bolt , Gr . 36 , Gr . 55 , Gr . 105 ( 1 / 2 ” — 2 ” nominal diameter )
• ASTM F1554 square head bolt , Gr . 36 , Gr . 55 , Gr . 105 ( 1 / 2 ” — 1-1 / 2 ” nominal diameter )
• ASTM F1554 heavy square head bolt , Gr . 36 , Gr . 55 , Gr . 105 ( 1 / 2 ” — 1-1 / 2 ” nominal diameter )
Section 17.6.3.2.1 notes that testing per the ACI test standard ACI 355.2 must be used to derive the pullout strength of a single anchor ( N p
) for a post-installed mechanical anchor ( e . g . expansion , screw or undercut anchor ). N p is one of the parameters used to calculate the nominal pullout strength ( N pn ). Mechanical anchor N p
-values can be derived from testing per the ICC-ES acceptance criteria AC193 in conjunction with the ACI standard ACI 355.2 . N p
-values for HIT-Z threaded rods used with HIT-HY 200 adhesive can be derived from testing per the ICC-ES acceptance criteria AC308 in conjunction with the ACI standard ACI 355.4 . Post-installed anchor N p
-values are provided in an ICC-ES evaluation report ( ESR ). PROFIS Engineering uses the N p
-values that are given in the ESR to calculate N pn for relevant post-installed anchors in its portfolio . The parameter ψ c , p is a modification factor for cracked or uncracked concrete conditions . PROFIS Engineering determines ψ c , p per Section 17.6.3.3.1 for the cast-in anchors in its portfolio . PROFIS Engineering always uses a ψ c , p
-value equal to 1.0 when calculating N pn for the post-installed anchors in its portfolio .
When modeling cast-in anchors in PROFIS Engineering , reference the Equations and Calculations section of the report for more information on the parameter
N p
. Reference the Variables section of the report for more information on the parameter ψ c , p
.
When modeling post-installed anchors in PROFIS Engineering , Reference the Equations section of the report for information on the following anchor-specific pullout parameters :
• N pn , f ́c if mechanical anchors are being modeled .
• N pn if HIT-HY 200 with HIT-Z and HIT-Z-R threaded rods is beingmodeled .
81 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions