1.0 TENSION
1.6 Sustained Load Failure Mode
Results 0.55 ϕN ba
Results ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering 0.55 ϕN ba
17.5.2.2 Design of adhesive anchors to resist sustained tension shall satisfy Eq . ( 17.5.2.2 ) 0.55 ϕN ba
≥ N ua , s ( 17.5.2.2 ) where N ba is the basic bond strength in tension of a single adhesive anchor and is N ua , s the factored sustained tensile load . 17.6.5 . 2.1 Basic bond strength of a single adhesive anchor in tension in cracked concrete , N ba
, shall be calculated by Eq .
( 17.6.5.2.1 )
N ba
= λ a т cr π da h ef
( 17.6.5.2.1 )
PROFIS Engineering parameters for calculating N ba :
N ba
= λ a т kxxx α N , seis πd a h ef
PROFIS Engineering calculations for N ba when used to calculate the sustained load parameter 0.55 ϕNba :
N ba
=
( λ a т xxxx α N , seis πd a h ef
)
17.2.4.1 Modification factor λ a for lightweight concrete shall be in accordance with Table 17.2.4.1 . It shall be permitted to use an alternate value of λ a if tests are performed and evaluated in accordance with ACI 355.2 or ACI 355.4 . Table 17.2.4.1 — Modification factor λ a for lightweight concrete
Cast-in and undercut anchor concrete failure
Case λ a
[ 1 ]
Expansion , screw , and adhesive anchor concrete failure
Adhesive anchor bond failure per Eq . ( 17.6.5.2.1 ) [ 1 ] λ shall be in accordance with 19.2.4
Example of a table in an ICC-ES evaluation report ( ESR ) showing the following parameters for calculating N ba :
• т kcr and т k , uncr
— characteristic bond stress values
• α N , seis — seismic reduction value
• d a — anchor element diameter
• h ef
— anchor effective embedment depth ICC-ES ESR-3187 Table 14
DESIGN INFORMATION Symbol Units
1.0 λ 0.8 λ 0.6 λ α N , seis
Nominal Rod Diameter ( in ). 3 / 8 1 / 2 5 / 8 3 / 4 7 / 8 1 1-1 / 4
Minimum Embedment |
h ef , min
|
in
( mm )
|
2-3 / 8
( 60 )
|
2-3 / 4
( 70 )
|
3-1 / 8
( 79 )
|
3-1 / 2
( 89 )
|
3-1 / 2
( 89 )
|
4
( 102 )
|
5
( 127 )
|
Maximum Embedment |
h ef , max
|
in
( mm )
|
7-1 / 2
( 191 )
|
10
( 254 )
|
12-1 / 2
( 318 )
|
15
( 381 )
|
17-1 / 5
( 445 )
|
20
( 508 )
|
25
( 635 )
|
Characteristic bond strength in cracked concrete |
т k , cr
|
psi
( Mpa )
|
1045
( 7.2 )
|
1135
( 7.8 )
|
1170
( 8.1 )
|
1260
( 8.7 )
|
1290
( 8.9 )
|
1325
( 9.1 )
|
1380
( 9.5 )
|
Characteristic bond strength in uncracked concrete |
т k , uncr
|
psi
( Mpa )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
Characteristic bond strength in cracked concrete |
т k , cr
|
psi
( Mpa )
|
1045
( 7.20 )
|
1135
( 7.80 )
|
1170
( 8.00 )
|
1260
( 8.67 )
|
1290
( 9.00 )
|
1325
( 9.00 )
|
1380
( 9.50 )
|
Characteristic bond strength in uncracked concrete |
т k , uncr
|
psi
( Mpa )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
2220
( 15.3 )
|
Characteristic bond strength in cracked concrete |
т k , cr
|
psi
( Mpa )
|
855
( 5.9 )
|
930
( 6.4 )
|
960
( 6.6 )
|
1035
( 7.1 )
|
1055
( 7.3 )
|
1085
( 7.5 )
|
1130
( 7.8 )
|
Characteristic bond strength in uncracked concrete |
т k , uncr
|
psi
( Mpa )
|
1820
( 12.6 )
|
1820
( 12.6 )
|
1820
( 12.6 )
|
1820
( 12.6 )
|
1820
( 12.6 )
|
1820
( 12.6 )
|
1820
( 12.6 )
|
Temperature Range A
Temperature Range B
Temperature Range C
Permissible installation conditions
Dry and water saturated concrete
Anchor Category
- ϕ d , ϕ ws
- 0.65
Reduction for Seismic Tension α N , seis
- 0.88 0.99 0.99 1.0 1.0 0.95 0.99
1
The provisions given in ACI 318-19 Section 17.5.2.2 are used to perform a check for adhesive anchors subjected to sustained tension loads . The check consists of calculating a capacity ( 0.55ϕN ba
), and comparing it to the highest ( factored ) sustained tension load ( N ua , s
) acting on a single anchor within the anchor group . The strength reduction factor ( ϕ-factor ) in Eq . ( 17.5.2.2 ) corresponds to the parameter “ ϕ bond
” in the PROFIS Engineering report . The parameter “ N ba
” corresponds to the “ basic bond strength ” for a single adhesive anchor without any fixed edge influences . N ba is calculated per Eq . ( 17.6.5.2.1 ); but an additional seismic modification factor that is derived from testing per the ICC-ES acceptance criteria AC308 is not given in Eq . ( 17.6.5.2.1 ), and must also be considered in the
N ba
-calculation . This seismic modification factor is designated “ α N , seis
”, and is included in PROFIS
Engineering N ba
-calculations when seismic conditions are being modeled . However , since seismic load is not considered a sustained load , PROFIS Engineering divides out any α N , seis
-value when calculating N ba per
Eq . ( 17.5.2.2 ).
Reference the Equations , Calculations and Results section of the report for more information on :
N ba
: basic bond strength parameters and calculations for the sustained tension load check
Reference the Results section of the report for more information on :
ϕ bond
: strength reduction factor for bond
N ua , s
: sustained factored tension load
161 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions