PART 4 SHEAR LOAD
Steel Failure Mode
Variables α V , seis
Variables 318-14 Chapter 17 Provision Comments for PROFIS Engineering
α V , seis
17.5.1.1 The nominal strength of an anchor in shear as governed by steel , V sa
, shall be evaluated by calculations based on the properties of the anchor material and the physical dimensions of the anchor . Where concrete breakout is a potential failure mode , the required steel shear strength shall be consistent with the assumed breakout surface .
17.5.1.2 The nominal strength of an anchor in shear , V sa , shall not exceed ( a ) through ( c ):
( a ) For cast-in headed stud anchor
V sa
= A se , V f uta
( 17.5.1.2a ) where A se , V is the effective cross-sectional area of an anchor in shear , in . 2 , and f uta shall not be taken greater than the smaller of 1.9fy a and 125,000 psi .
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
= 0.6 A se , V f uta
( 17.5.1.2b ) where A se , V is the effective cross-sectional area of an anchor in shear , in . 2 , and f uta shall not be taken greater than the smaller of 1.9fy a and 125,000 psi . ( c ) For post-installed anchors where sleeves extend through the shear plane , V sa shall be based on the results of tests performed and evaluated according to ACI 355.2 . Alternatively , Eq . ( 17.5.1.2b ) shall be permitted to be used
Excerpts from an adhesive anchor ICC-ESR referencing the parameter α V , seis .
ICC-ESR-3814 4.1.11 Design Strength in Seismic Design Categories C , D , E and F :
……………………………………. The nominal steel shear strength , V sa
, must be adjusted by α V , seis ……………..
ICC-ESR-3814 Table 6A
DESIGN INFORMATION Symbol Units
ASTM F1554
Gr . 36
Nominal strength as governed by steel strength
Reduction factor , seismic shear
Nominal rod diameter ( in ). 3 / 8 1 / 2 5 / 8 3 / 4 7 / 8 1 1-1 / 4
V sa lb - 4940 7865 11,640 16,070 21,080 33,725 α V , seis
- 0.60
Post-installed adhesive anchor systems can be shown compliance 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 ICC-ESR . Pre-calculated values for nominal steel strength in shear are given in the ICC-ESR steel design tables . PROFIS Engineering uses these values to define the nominal steel strength in shear .
Adhesive anchor ICC-ESR include pre-calculated V sa values for the nominal static shear steel strength of an anchor element . An additional reduction factor designated “ α V , seis
” is applied to the V sa
-value when calculating the shear nominal steel strength for seismic load conditions . α V , seis is only used as a shear steel strength design parameter with adhesive anchor elements . α V , seis
-values are derived from AC308 / ACI 355.4 testing , and will be given in the ICC-ESR steel design tables .
Generally speaking , when modeling static load conditions for an adhesive anchor system , the PROFIS Engineering report shows the V sa
-value from the ICC-ESR in the Calculations and Results section . If seismic load conditions are being modeled , PROFIS Engineering applies the α V , seis
-value given in the ICC-ESR to the V sa -value and shows the product of these two parameters as “ V sa , eq
” in the
Calculations and Results section of the report .
When modeling the HIT-HY 200 adhesive anchor system for static load conditions in PROFIS Engineering , the V sa
-value given in the ICC-ESR is shown in the Variables section of the report as “ 0.6 A se , V f uta
”. However , this parameter is still shown as “ V sa
” in the Calculations and Results section of the report . When modeling HIT-HY 200 for seismic load conditions , the α V , seis
-value is also shown in the Variables section of the report , and PROFIS Engineering shows the product “( α V , seis
)( 0.6 A se , V f uta
)” as “ V sa , eq
” in the Calculations and Results section of the report .
Reference the Calculations and Results section of the PROFIS Engineering report for more information on :
V sa
: Nominal ( static ) steel strength in shear
V sa , eq
: Nominal ( seismic ) steel strength in shear
Reference the Variables section of the PROFIS Engineering report for more information on :
A se , V
: Tensile stress area of an anchor element
0.6 A se , V f uta
: Pre-calculated V sa
-value from ICC-ESR
302 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions