PART 3 TENSION LOAD
Pullout Failure Mode
Results N pn , f ́c
Results ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering mechanical anchors
N pn , f ́c
= N p , 2500 λ a
( f ́c / 2500 ) n
17.4.3.1 The nominal pullout strength of a single cast-in , post-installed expansion , and postinstalled undercut anchor in tension , N pn
, shall not exceed
N pn
= ψ c , p
N p
( 17.4.3.1 ) 17.4.3 . 2 For post-installed expansion and 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 .
Excerpt from ICC-ESR-1917 for the Hilti Kwik Bolt-TZ ( KB-TZ ) expansion anchor referencing provisions for calculating nominal pullout strength in tension ( N pn
) per ACI 318-14 Eq . ( 17.4.3.1 ).
PROFIS Engineering calculates nominal pullout strength in tension ( N pn
) per ACI 318-14 Eq . ( 17.4.3.1 ). For mechanical anchors , the Equations and Results section of the report designate N pn as “ N pn , f ́c ”. Per ACI 318-14 Section 17.4.3.2 , the parameter “ N p
“ for mechanical anchors must be derived from testing . PROFIS Engineering uses the N p
-value given in the mechanical anchor ICC-ESR to calculate N pn , f ́c . PROFIS Engineering always uses ψ c , p
= 1.0 for mechanical anchor calculations .
N p
-values in the ICC-ESR are derived from testing in 2500 psi concrete ; therefore , the PROFIS Engineering equation for N pn , f ́c designates the N p -value from the
ICC-ESR as “ N p , 2500 ”.
4.1.4 Requirements for Static Pullout Strength in Tension : The nominal pullout strength of a single anchor in accordance with ACI 318-14 17.4.3.1 and 17.4.3.2 or ACI 318-11 D . 5.3.1 and D . 5.3.2 , respectively , as applicable , in cracked and uncracked concrete ,
N p , cr and N p , uncr , respectively , is given in Tables 3 and 4 . For all design cases , ψ c , p
= 1.0 . In accordance with ACI 318-14 17.4.3 or ACI 318-11 D . 5.3 , as applicable , the nominal pullout strength in cracked concrete may be calculated in accordance with the following equation :
The mechanical anchor ICC-ESR provisions permit the N p
-value given in the ICC-ESR design tables to be increased by a factor ( f ́c / 2500 ) n for design purposes when the concrete compressive strength ( f ́c ) for the application is greater than 2500 psi . Reference Section 4.1.4 of the mechanical anchor ICC-ESR for specific information about this factor . PROFIS Engineering multiplies “ N p , 2500
” by ( f ́c / 2500 ) n when calculating nominal pullout strength for a mechanical anchor .
N p , f ́c
= N p , cr f ́c ( Eq-1 ) 2500
In regions where analysis indicates no cracking in accordance with ACI 318-14 17.4.3.6 or ACI 318- 11 D . 5.3.6 , as applicable , the nominal pullout strength in tension may be calculated in accordance with the following equation :
N p , f ́c
= N p , uncr f ́c ( Eq-2 ) 2500
Where values for N p , cr or N p , uncr are not provided in Table 3 or Table 4 , the pullout strength in tension need not be evaluated . Excerpt from ICC-ESR-1917 showing values for N p , cr and N p , uncr derived from testing in 2500 psi concrete per AC193 / ACI 355.2 .
ICC-ESR-1917 Table 3
DESIGN INFORMATION
Effective min . embedment
Pullout strength cracked concrete
Pullout strength uncracked concrete
Symbol Units
Nominal anchor diameter ( in .) 3 / 8 1 / 2 5 / 8 3 / 4 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 n p , uncr lb 2160 2515 4110 NA 5515 NA 9145 NA 8280 10680
N p , cr lb NA 2270 3160 NA 4915 NA NA
PROFIS Engineering applies a lightweight concrete modification factor ( λ a
) to the
Np-value if lightweight concrete is being modeled .
If pullout is not a possible controlling failure mode for a particular anchor diameter and embedment depth , the ICC-ESR will show “ NA ”, and no N p
-value will be given . PROFIS Engineering does not perform pullout calculations for anchor diameters / embedment ’ s for which “ NA ” is given in the ICC-ESR
Reference the Variables section of the report for more information on the following parameters :
• N p , 2500 — tested pullout value in 2500 psi concrete
• λ a
— lightweight concrete modification factor
• f ́c — concrete compressive strength
Reference the Calculations section of the report for more information on the parameter ( f ́c / 2500 ) n .
Reference the Equations section of the report for more information on the parameter N pn , f ́c
.
When modeling cast-in anchors , PROFIS Engineering calculates nominal the pullout strength in tension ( N pn
) per ACI 318-14 Eq . ( 17.4.3.1 ), and the parameter N p per ACI 318-14 Eq . ( 17.4.3.4 ). Reference the cast-in anchor report sections relevant to pullout strength in tension for more information .
94 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions