PROFIS Design Guide: US-EN Summer 2021 | Page 88

Pullout Failure Mode

Variables N _{p , 2500}

Variables ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering

N _{p , 2500}

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 .

PROFIS Engineering uses this equation to calculate a nominal pullout strength for mechanical anchors :

N _{pn , f ́c}

= N _{p , 2500} λ _a

( _{f ́c} / 2500 ) ⁿ

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

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 :

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} ”. Nominal pullout strength is calculated with the parameter “ N _p

” which is defined in ACI 318-14 Chapter 2 as the pullout strength in tension of a single anchor in cracked concrete .

Mechanical anchor N _p

-values are derived from testing per the ICC-ES acceptance criteria AC193 in conjunction with the ACI standard ACI 355.2 . These N _p

-values are specific to the concrete condition ( cracked or uncracked ), and to the anchor diameter ( d _a

) and effective embedment depth ( h _ef ). PROFIS Engineering uses the

ICC-ESR N _p -values to calculate the nominal pullout strength for a mechanical anchor .

N _p

-values in the ICC-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 ICC-ESR as “ N _{p , 2500}

”. 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 , 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 .

• 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 Results 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 .

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

88 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions