PART 3 TENSION LOAD
Pullout Failure Mode
Results ϕN pn , f ́c
Results ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering mechanical anchors
ϕN pn , f ́c
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 ).
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 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
Excerpt from ICC-ESR-1917 showing values for N p , cr , N p , uncr and ϕ-factors .
ICC-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 .
( mm )
|
1-1 / 2
38
|
2
51
|
2-3 / 4
70
|
2
51
|
3-1 / 4
83
|
3-1 / 8
79
|
4
102
|
3-1 / 4
83
|
3-3 / 4
95
|
4-3 / 4
121
|
Pullout strength cracked concrete |
N p , uncr
|
lb
( kn )
|
2160
( 9.6 )
|
2515
( 11.2 )
|
4110
( 18.3 )
|
NA |
5515
( 24.5 )
|
NA |
9145
( 40.7 )
|
NA |
8280 10680
( 36.8 )
( 47.5 )
|
Pullout strength uncracked concrete |
N p , cr
|
lb
( kn )
|
NA |
2270
( 10.4 )
|
3160
( 14.1 )
|
NA |
4915
( 21.9 )
|
NA |
NA |
NA |
NA |
NA |
Strength reduction 0 factor for tension , concrete failure modes , or pullout , Condition B |
0.55 |
0.65 |
ACI 318-14 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- 14 . 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 for the mechanical anchor . The PROFIS Engineering report designates the ESR pullout values “ N p , 2500
”, and the calculated nominal pullout strength “ N pn , f ́c
”,
The ICC-ESR for the mechanical anchors in the PROFIS Engineering portfolio also include ϕ-factors that are derived from testing per AC193 / ACI 355.2 . When modeling static load conditions for a mechanical anchor , PROFIS Engineering uses the ϕ-factors given in the ICC-ESR to calculate the design pullout strength . These ϕ-factors correspond to “ Condition B ” as defined in ACI 318-14 Section 17.3.3 , and are designated “ ϕ concrete
” in the PROFIS Engineering report . Design pullout strength for static load conditions is designated “ ϕN pn , f ́c
” in the PROFIS Engineering report , and is calculated as “ ϕ concrete
N pn , f ́c
” using the values from the mechanical anchor ICC-ESR . If seismic load conditions are being modeled ; PROFIS Engineering applies the additional 0.75 reduction factor to “ ϕ concrete
N pn , f ’ c
” per Section
17.2.3.4.4 , and designates this factor “ ϕ seismic ”. The report parameter “ ϕN pn , f ’ c
” corresponds to “ ϕ seismic ϕ concrete
N pn , f ́c
”.
Reference the Equations and Results section of the report for more information on the parameter N pn , f ́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 318-14 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 .
17.3.3 Strength reduction factor ϕ for anchors in concrete shall be as follows when the load combinations of 5.3 are used :
Condition A applies where supplementary reinforcement is present except for pullout and pryout strengths .
Condition B applies where supplementary reinforcement is not present and for pullout and pryout strengths .
17.2.3.4.4 The anchor design tensile strength for resisting earthquake forces shall be determined from consideration of ( a ) through ( e ) for the failure modes given in Table 17.3.1.1 assuming the concrete is cracked unless it can be demonstrated that the concrete remains uncracked :
( c ) 0.75ϕN pn for a single anchor or for the most highly stressed individual anchor in a group of anchors
100 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions