PART 3 TENSION LOAD
Sustained Tension Load — Bond Strength
Variables h ef
Variables ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering
h ef
17.3.1.2 For the design of adhesive anchors to resist sustained tension loads , in addition to 17.3.1.1 , Eq . ( 17.3.1.2 ) shall be satisfied .
0.55 ϕN ba ≥ N ua , s
( 17.3.1.2 )
Where N ba is determined in accordance with 17.4.5 . 2 . 17.4.5 . 2 The basic bond strength of a single adhesive anchor in tension in cracked concrete , N ba
, shall not exceed
Example :
N ba
= λ a т cr π da h ef
( 17.4.5 . 2 )
Example of a table in an ICC-ESR showing effective embedment depth values ( h ef , min and h ef , max
) for threaded rod elements used with an adhesive anchor system . ICC-ESR-3187 Table 14
DESIGN INFORMATION Symbol Units
Nominal Rod Diameter ( in ). 3 / 8 1 / 2 5 / 8 3 / 4 7 / 8 1 1-1 / 4
Minimum Embedment |
h ef , max
|
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 , min
|
in
( mm )
|
7-1 / 2
( 191.00 )
|
10
( 254.00 )
|
12-1 / 2
( 318.00 )
|
15
( 381.00 )
|
17-1 / 5
( 445.00 )
|
20
( 508.00 )
|
25
( 635.00 )
|
Temperature Range A 2
Temperature Range B 2
Temperature
Range C 2
Characteristic bond strength in cracked concrete
Characteristic bond strength in uncracked concrete
Characteristic bond strength in cracked concrete
Characteristic bond strength in uncracked concrete
Characteristic bond strength in cracked concrete
Characteristic bond strength in uncracked concrete
т k , cr
|
psi
( Mpa )
|
1045
( 7.20 )
|
1135
( 7.80 )
|
1170
( 8.10 )
|
1260
( 8.70 )
|
1290
( 8.90 )
|
1325
( 9.10 )
|
1380
( 9.50 )
|
т k , uncr
|
psi
( Mpa )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
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 )
|
т k , uncr
|
psi
( Mpa )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
2220
( 15.30 )
|
т k , cr
|
psi
( Mpa )
|
855
( 5.90 )
|
930
( 6.40 )
|
960
( 6.60 )
|
1035
( 7.10 )
|
1055
( 7.30 )
|
1085
( 7.50 )
|
1130
( 7.80 )
|
t k , uncr
|
psi
( Mpa )
|
1820
( 12.60 )
|
1820
( 12.60 )
|
1820
( 12.60 )
|
1820
( 12.60 )
|
1820
( 12.60 )
|
1820
( 12.60 )
|
1820
( 12.60 )
|
1 Bond strength values correspond to concrete compressive strength = 2500 psi . For concrete compressive strength between 2500 psi and 800 psi , the tabulated
f ́c f ́c characteristic bond strength may be increased by a factor of ( / 2500 ) f ́c 0 ,. 1 .
2 Temperature Range A : Maximum short term temperature = 130 ° F , Maximum long term temperature = 110 ° F . Temperature Range B : Maximum short term temperature = 176 ° F , Maximum long term temperature = 110 ° F . Temperature Range C : Maximum short term temperature = 248 ° F , Maximum long term temperature = 162 ° F .
The parameter h ef is defined as the “ effective embedment depth of an anchor ”. This parameter corresponds to the embedded portion of the anchor that is “ effective ” in transferring tension load from the anchor into the concrete . When calculating the sustained load strength defined by Equation ( 17.3.1.2 ), h ef is used to calculate the parameter “ N ba
” that is defined in Equation ( 17.4.5.2 ),
The PROFIS Engineering adhesive anchor portfolio permits bond strength calculations with the following anchor elements :
• Threaded rods
• Reinforcing bars
• Internally threaded inserts
• Specialty anchor elements
Testing per the ICC-ES acceptance criteria AC308 and the ACI test standard ACI 355.4 is used to derive product-specific data that is used in ACI 318-14 bond strength calculations for an adhesive anchor system . Data derived from this testing , as well as some of the parameters used to develop this data , are provided in an ICC-ESR . The minimum effective embedment depth ( h ef , min
) derived from this testing is specific to the anchor element ( e . g . threaded rod , rebar , internally threaded insert ), and to the adhesive product . AC308 limits the maximum effective embedment depth ( h ef , max
) for adhesive anchor systems to a value of 20 times the anchor diameter ( 20d a
). For post-installed adhesive anchors , PROFIS Engineering permits users to input h ef values that are within the embedment depth range given in the ICC-ESR for a specific anchor element , diameter , and adhesive product .
post-installed adhesive anchor h ef , min
≤ h ef ≤ h ef , max where h ef , min and h ef , max
(= 20da ) are given in the anchor ICC-ESR
151 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions