1.0 TENSION
1.3 Pullout Failure Mode
Results ϕN pn , f ́c
Results ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering mechanical anchors
ϕN pn , f ́c
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 ) ………………………………………….
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
) per ACI 318-14 Eq . ( 17.4.3.1 ). 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 , 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
Excerpt from ESR-1917 showing values for N p , cr , N p , uncr and ϕ-factors .
ICC-ES ESR-1917 Table 3
DESIGN INFORMATION
Symbol Units
Nominal anchor diameter ( in .) 3 / 8 1 / 2 5 / 8 3 / 4
Effective min . embedment |
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 |
Pullout strength uncracked concrete |
N p , uncr
|
lb |
2160 |
2515 |
4110 |
NA |
5515 |
NA |
9145 |
NA |
8280 10680 |
Pullout strength cracked concrete |
N p , cr
|
lb |
NA |
2270 |
3160 |
NA |
4915 |
|
NA |
|
NA |
Strength reduction factor for tension , concrete failure modes or pullout . Condition B |
0.55 |
0.65 |
ACI 318-19 strength design provisions for tension define the parameter “ design strength ” as the product of a “ nominal strength ” ( N N
) and one or more strength reduction factors ( ϕ-factors ). Nominal pullout strength in tension ( N pn
) is always calculated for a single anchor when designing with the provisions of ACI 318-19 . Per Section 17.6.3.2.1 , PROFIS Engineering calculates the nominal pullout strength ( N pn
) for the mechanical anchors in its portfolio using pullout values derived from testing per the ICC-ES acceptance criteria AC193 in conjunction with the ACI test standard ACI 355.2 . These pullout values are given in the ICC-ES evaluation report ( ESR ) for the mechanical anchor . The PROFIS Engineering report designates the ESR pullout values “ N p , 2500
”, and the calculated nominal pullout strength “ N pn , ƒ ́c ”,
When modeling static load conditions for a mechanical anchor , PROFIS Engineering uses the strength reduction factor ( ϕ-factor ) given in the anchor ESR , which typically corresponds to one of the ϕ-factors given in ACI 318-19 Table 17.5.3 ( c ), to calculate the design pullout strength . This ϕ-factor is designated “ ϕ concrete
” in the PROFIS Engineering report . Design pullout strength for static load conditions is designated “ ϕN pn , ƒ ́c
” in the PROFIS Engineering report , and is calculated as “ ϕ concrete
N pn , ƒ ́c
” using the values from the mechanical anchor ESR . If seismic load conditions are being modeled ; PROFIS Engineering applies the additional 0.75 reduction factor to “ ϕ concrete
N pn , ƒ ́c
” per Section 17.10.5.4 , and designates this factor “ ϕ seismic ”. The report parameter “ ϕN pn , ƒ ́c
” corresponds to
“ ϕ seismic ϕ concrete
N pn , ƒ ́c
”.
Reference the Equations and Results section of the report for more information on the parameter N pn , ƒ ́c
.
Reference the Results section of the report for more information on the parameters ϕ concrete and ϕ seismic
.
When modeling HIT-Z and HIT-Z-R threaded rods with HIT-HY 200 adhesive in PROFIS Engineering , Reference the Equations and Results section of the report for information on the pullout parameter ϕN pn
.
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 .
17.5.3 Strength reduction factor ϕ for anchors in concrete shall be in accordance with Tables …… ……….. 17.5.3 ( c )…………………
Table 17.5.3 ( c ) — Anchor strength governed by concrete pullout , or pryout strength
Type of anchor installation
Anchor Category [ 1 ] from ACI 355.2 or ACI 355.4
Strength reduction factor ϕ
Tension ( concrete pullout )
Cast-in anchors |
Not applicable |
0.70 |
|
1 |
0.65 |
Post-installed anchors |
2 |
0.55 |
|
3 |
0.45 |
Shear ( concrete pryout )
17.10.5.4 The anchor design tensile strength shall be calculated from ( a ) through ( e ) ……………………………………………………………………………………………………
( c ) 0.75ϕN pn for a single anchor or for the most highly stressed individual anchor in an anchor group
102 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions
0.70