2.0 SHEAR
2.4 Stand-off Failure Mode
Calculations post-Installed anchor V sa
Calculations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering post-Installed anchor
V sa
17.7.1.1 Nominal steel strength of anchors in shear as governed by the steel , V sa
, shall be evaluated based on the properties of the anchor material and the physical dimensions of the anchors . If concrete breakout is a potential failure mode , the required steel shear strength shall be consistent with the assumed breakout surface .
17.7.1.2 Nominal strength of an anchor in shear , V sa
, shall not exceed ( a ) through ( c ): …………………………………………………..
( b ) For cast-in headed bolt and hooked bolt anchors and for post-installed anchors where sleeves do not extend through the shear plane
V sa
= 0.6A se , V ƒ uta
( 17.7.1.2b ) where A se , V is the effective cross-sectional area of an anchor in shear , in . 2 , and the value of ƒ uta shall not exceed either 1.9ƒ ya or 125,000 psi . ( c ) For post-installed anchors where sleeves extend through the shear plane , V sa shall be based on the 5 percent fractile of results of tests performed and evaluated in accordance with ACI 355.2 . Alternatively , Eq . ( 17.7.1.2b ) shall be permitted to be used .
Excerpt from a mechanical anchor ESR showing V sa and V sa , eq values .
ICC-ES ESR 1917 Table 3
Design information
Effective min . embedment
Steel strength in shear
Steel strength in shear , seismic
Symbol Units
Nominal anchor diameter ( in .) 3 / 8 1 / 2 5 / 8 3 / 4 h ef in . 1-1 / 2 2 2-3 / 4 2 3-1 / 4 3-1 / 8 4 3-1 / 4 3-3 / 4 4-3 / 4
V sa lb 2180 3595 5495 8090 13,675
V sa , eq lb 2180 2255 5495 7600 11,745
Excerpt from an adhesive anchor ESR showing parameters for V sa
.
ICC-ES ESR-3187 Table 6A
DESIGN INFORMATION Symbol Units
Nominal rod diameter ( in ). 3 / 8 1 / 2 5 / 8 3 / 4 7 / 8 1 1-1 / 4
ACI 318-19 Chapter 2 defines the parameter V sa as : “ nominal shear strength of a single anchor or individual anchor in a group of anchors as governed by the steel strength ”.
V sa is always calculated for a single anchor when designing with ACI 318-19 provisions .
Post-installed mechanical anchors can be qualified for recognition under the International Building Code ( IBC ) via testing per the ICC-ES acceptance criteria AC193 and the ACI test standard ACI 355.2 . Data derived from this testing is given in an ICC-ES evaluation report ( ESR ). Pre-calculated V sa
-values derived from AC193 / ACI 355.2 testing are given in mechanical anchor ESR design tables . Although parameters such as A se , V and ƒ uta may be given in the ESR ,
PROFIS Engineering uses the pre-calculated V sa
-values to define the nominal steel strength in shear . Mechanical anchor ESR-values are specific to static ( V sa
) or seismic ( V sa , eq
) load conditions . The Calculations section of the PROFIS Engineering report for a mechanical anchor references “ V sa
” for static load conditions and “ V sa , eq
” for seismic load conditions ”.
Post-installed adhesive anchor systems can be qualified for recognition under the IBC via testing per the ICC-ES acceptance criteria AC308 and the ACI test standard ACI 355.4 . Data derived from this testing is given in an ESR . Precalculated values for V sa are given in the ESR steel design tables . Although parameters such as A se , V and ƒ uta may be given in the ESR , PROFIS Engineering uses the pre-calculated V sa -values to define the nominal steel strength in shear .
Adhesive anchor ESR V sa
-values are specific to static load conditions . An additional reduction factor designated “ α V , seis
” is applied to the V sa
-value when calculating nominal steel strength in shear for seismic load conditions .
α V , seis
-values are derived from AC308 / ACI 355.4 testing , and will be given in the ESR steel design tables . The Calculations section of the PROFIS Engineering report for an adhesive anchor system references “ V sa
” when modeling static load conditions and “ V sa , eq ” when modeling seismic load conditions , where
V sa , eq
= αV , seis V sa
. One exception to this nomenclature is with respect to the HIT-HY 200 adhesive system . The Equations section of the PROFIS Engineering report for HIT-HY 200 steel strength parameters references “ V sa
= ( 0.6 A se , V ƒ uta
)” when modeling static load conditions and
“ V sa = α V , seis
( 0.6 A se , V ƒ uta
)” when modeling seismic load conditions , but the Calculations section of the report simply references “ V sa
” when modeling static load conditions and “ V sa , eq ” when modeling seismic load conditions
ASTM F1554
Gr . 36
Nominal strength as governed by steel strength
Reduction factor , seismic shear
V sa lb - 4940 7865 11,640 16,070 21,080 33,725 α V , seis
- 0.60
Reference the Equations and Results section of the report for more information on V sa and V sa , eq
.
Reference the Variables section of the report for more information on the parameters A se , V
, ƒ uta , α V , seis and ( 0.6 A se , V ƒ uta
).
296 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions