PART 3 TENSION LOAD
Sustained Tension Load — Bond Strength
Variables d a
Variables ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering
d a
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 bond strength table in an ICC-ESR showing parameters that are dependent on the anchor element diameter
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 )
|
10
( 254 )
|
12-1 / 2
( 318 )
|
15
( 381 )
|
17-1 / 5
( 445 )
|
20
( 508 )
|
25
( 635 )
|
Temperature Range A
Temperature Range B
Temperature
Range C
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
( 7.2 )
|
1135
( 7.8 )
|
1170
( 8.1 )
|
1260
( 8.7 )
|
1290
( 8.9 )
|
1325
( 9.1 )
|
1380
( 9.5 )
|
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 )
|
т k , cr
|
psi
( Mpa )
|
1045
( 7.2 )
|
1135
( 7.8 )
|
1170
( 8.0 )
|
1260
( 8.67 )
|
1290
( 9.0 )
|
1325
( 9.0 )
|
1380
( 9.5 )
|
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 )
|
т k , cr
|
psi
( Mpa )
|
855
( 5.0 )
|
930
( 6.4 )
|
960
( 6.6 )
|
1035
( 7.1 )
|
1055
( 7.3 )
|
1085
( 7.5 )
|
1130
( 7.8 )
|
t 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 )
|
Reduction for Seismic Tension α n , seis - 0.88 1.0 1.0 1.0 1.0 0.97 1.0
The parameter da is defined in ACI 318-14 Chapter 2 as the “ outside diameter ” of an anchor or the “ shaft diameter ” of a headed stud , headed bolt or hooked bolt . Therefore , d a corresponds to the external diameter of an anchor element .
When calculating the sustained load strength defined by Equation ( 17.3.1.2 ), d a is used to calculate the parameter “ N ba
” that is defined in Equation ( 17.4.5.2 ), Other parameters given in Eq . 17.4.5.2 such as effective embedment depth ( h ef
), characteristic bond stress ( т k ), and α N , seis are also dependent on the diameter of the anchor element being used .
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
Information about these anchor element types is given in the ICC-ESR for an adhesive anchor system . PROFIS Engineering uses the anchor diameter parameter referenced in the ICC-ESR bond strength tables for an adhesive anchor system to calculate N ba for a specific anchor element . When design with a threaded rod or reinforcing bar is selected , PROFIS Engineering uses the nominal diameter of the anchor element to calculate N ba
. When design with Hilti HIS-N and HIS-RN internally threaded inserts is selected , PROFIS Engineering uses the outside diameter of the insert to calculate N ba
. Below are illustrations showing how the parameter d a for calculating N ba can be defined for various anchor elements .
The parameter “ d hole
” noted in the illustrations corresponds to the diameter of the drilled hole into which the adhesive product and anchor element are inserted .
Reference the Variables section of the PROFIS Engineering report for more information on :
h ef
:
т k , c
:
Effective embedment depth Characteristic bond stress
Reference the Calculations section of the PROFIS Engineering report for more information on :
N ba
:
Basic bond strength for a single adhesive anchor
150 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions