1.0 TENSION
1.1 Bond Failure Mode
Variables α N , seis
Variables ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
α N , seis
ACI 318-19 equation for calculating N ba
: 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 πd a h ef
( 17.6.5.2.1 )
PROFIS Engineering equation for calculating N ba :
N ba
= λ a т k , c α N , seis πd a h ef
Example of a table in an ICC-ES evaluation report ( ESR ) showing the seismic modification factor
α N , seis
.
ICC-ES 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 , min in 2-3 / 8 2-3 / 4 3-1 / 8 3-1 / 2 3-1 / 2 4 5 ( mm ) ( 60 ) ( 70 ) ( 79 ) ( 89 ) ( 89 ) ( 102 ) ( 127 )
Maximum Embedment h ef , max in 7-1 / 2 10 12-1 / 2 15 17-1 / 5 20 25 ( mm ) ( 191 ) ( 254 ) ( 318 ) ( 381 ) ( 445 ) ( 508 ) ( 635 )
Temperature Range A
Temperature Range B
Temperature Range C
Permissible installation conditions
Characteristic bond strength psi 1045 1135 1170 1260 1290 1325 1380 in cracked concrete т k , cr ( Mpa ) ( 7.2 ) ( 7.8 ) ( 8.1 ) ( 8.7 ) ( 8.9 ) ( 9.1 ) ( 9.5 )
Characteristic bond strength psi 2220 2220 2220 2220 2220 2220 2220 in uncracked concrete т k , uncr ( Mpa ) ( 15.3 ) ( 15.3 ) ( 15.3 ) ( 15.3 ) ( 15.3 ) ( 15.3 ) ( 15.3 )
Characteristic bond strength psi 1045 1135 1170 1260 1290 1325 1380 in cracked concrete т k , cr ( Mpa ) ( 7.20 ) ( 7.80 ) ( 8.00 ) ( 8.67 ) ( 9.00 ) ( 9.00 ) ( 9.50 )
Characteristic bond strength psi 2220 2220 2220 2220 2220 2220 2220 in uncracked concrete т k , uncr ( Mpa ) ( 15.3 ) ( 15.3 ) ( 15.3 ) ( 15.3 ) ( 15.3 ) ( 15.3 ) ( 15.3 )
Characteristic bond strength psi 855 930 960 1035 1055 1085 1130 in cracked concrete т k , cr ( Mpa ) ( 5.9 ) ( 6.4 ) ( 6.6 ) ( 7.1 ) ( 7.3 ) ( 7.5 ) ( 7.8 )
Characteristic bond strength psi 1820 1820 1820 1820 1820 1820 1820 in uncracked concrete т k , uncr ( Mpa ) ( 12.6 ) ( 12.6 ) ( 12.6 ) ( 12.6 ) ( 12.6 ) ( 12.6 ) ( 12.6 )
Dry and water saturated concrete
Anchor Category
- ϕ d , ϕ ws
-
1
0.65 α N , seis is a seismic modification factor that is used to calculate the basic bond strength of an adhesive anchor ( Nba ). Values for α N , seis are derived from testing per the ICC-ES acceptance criteria AC308 . α N , seis
-values are specific to the adhesive product , the anchor element being used with that product , and the anchor element diameter . Values for α N , seis are given in the ICC-ES evaluation report ( ESR ) for an adhesive anchor system . The parameter N ba corresponds to a calculated bond strength for a single adhesive anchor element without any fixed edge or spacing influences . Calculation of N ba is predicated on the characteristic bond stress of the adhesive product ( т cr or т uncr
), and the anchor element geometry ( πd a and h ef
), where d a corresponds to the nominal diameter of the anchor element and h ef corresponds to the effective embedment depth that has been input into PROFIS Engineering for the selected anchor element . Calculation of N ba also includes a modification factor for lightweight concrete ( λ a
).
Adhesive anchor systems can be qualified for recognition under the International Building Code ( IBC ) via testing per AC308 . AC308 references the ACI test standard for qualifying adhesive anchor systems ( ACI 355.4 ), but ACI 355.4 does not include any provisions for determining α N , seis
. Since ACI 355.4 does not reference α N , seis , ACI 318 anchoring-to-concrete provisions do not reference α N , seis
.
However , since AC308 does include provisions for determining α N , seis
, adhesive anchor systems qualified per AC308 to receive recognition under the IBC include
α N , seis as a parameter for calculating N ba .
PROFIS Engineering uses the α N , seis
-values given in the ICC-ES evaluation report ( ESR ) for an adhesive anchor system to calculate N ba
. The PROFIS Engineering report therefore shows α N , seis in the Variables section , and as a parameter for calculating N ba in the Equations section .
Reference the Variables section of the PROFIS Engineering report for more information on the following parameters :
λ a
: lightweight concrete modification factor .
т k , xxxx
: characteristic bond stress for cracked or uncracked concrete .
d a
: anchor element diameter .
h ef
: effective embedment depth that has been selected for the anchor being modeled .
Reference the Calculations section of the PROFIS Engineering report for more information on the parameter N ba
.
Reduction for Seismic Tension α N , seis
- 0.88 0.99 0.99 1.0 1.0 0.95 0.99
29 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions