PROFIS Design Guide - AC 318-19 July 2022 | Page 83

1.3 Pullout Failure Mode

Equations N _{pn , ƒ ́c}

Equations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering mechanical anchors

N _{pn , f ́c}

= N _{p , 2500} λ _a

( _{ƒ ́c} / 2500 ) ⁿ

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 :

N _pn

= ψ _{c , p}

N _p

( 17.6.3.1 )

PROFIS Engineering calculates nominal pullout strength in tension ( N _pn

) per ACI 318-19 Eq . ( 17.6.3.1 ). For mechanical anchors , the Equations and Results section of the report designate N _pn as “ N _{pn , ƒ ́c} ”. Per ACI 318-19 Section 17.6.3.2.1 , the parameter “ N _p

“ for mechanical anchors must be derived from testing . PROFIS Engineering uses the N _p

-value given in the mechanical anchor ESR to calculate

N _{pn , ƒ ́c}

. PROFIS Engineering always uses ψ _{c , p} = 1.0 for mechanical anchor calculations . where ψ _{c , P} is given in 17.6.3.3 . 17.6.3.2 Basic single anchor pullout strength , N _p

. 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 .

Excerpt from ESR-1917 for the Hilti Kwik Bolt-TZ ( KB-TZ ) expansion anchor referencing provisions for calculating nominal pullout strength in tension ( N _pn

).

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 :

N _p

-values in the ESR are derived from testing in 2500 psi concrete ; therefore , the Variables section of the PROFIS Engineering report designates the N _p

-value from the ESR as “ N _{p , 2500} ”. The ESR provisions shown to the left illustrate how the

N _p

-value given in the ESR design tables ( derived from testing in 2500 psi concrete ) can be increased for design purposes when the concrete compressive strength ( _{f ́c} ) for the application is greater than 2500 psi . Generally speaking , the factor by which “ N _{p , 2500}

” can be increased equals ( _{ƒ ́c / 2500} ) ^{0 . 5} ; however , the parameter ( _{ƒ ́c / 2500}

) may be raised to another power . Reference Section 4.1.4 of the mechanical anchor ESR for specific information about this factor . PROFIS Engineering multiplies “ N _{p , 2500}

” by ( _{ƒ ́c} / 2500 ) ⁿ when calculating nominal pullout strength for a mechanical anchor . The calculated value for ( _{ƒ ́c / 2500}

) ⁿ is shown in the Calculations section of the mechanical anchor report . If pullout is not a possible controlling failure mode for a particular anchor diameter and embedment depth , the 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 ESR . PROFIS Engineering applies a lightweight concrete modification factor ( λ _a

) to the N _p -value if lightweight concrete is being modeled .

N _{p , f ́c}

= N _{p , cr ƒ ́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 ƒ ́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 ESR-1917 showing values for N _{p , cr} and N _{p , uncr} derived from testing in 2500 psi concrete per AC193 / ACI 355.2 .

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 .

• _{ƒ ́c} — concrete compressive strength .

Reference the Calculations section of the report for more information on the parameter ( _{ƒ ́c} / 2500 ) ⁿ .

Reference the Results section of the report for more information on the parameter

N _{pn , ƒ ́c}

.

When modeling cast-in anchors , PROFIS Engineering calculates nominal the pullout strength in tension ( N _pn

) per ACI 318-19 Eq . ( 17.6.3.1 ), and the parameter

N _p per ACI 318-19 Eq . ( 17.6.3.2.2a ). Reference the cast-in anchor report sections relevant to pullout strength in tension for more information .

ICC-ES ECR-1917 Table 3

DESIGN INFORMATION

Effective min . embedment

Pullout strength cracked concrete

Pullout strength uncracked concrete

83 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions