2.0 SHEAR
2.1 Concrete Breakout Failure Mode
Variables e c , V
Variables ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
e c , V
17.7.2.3.1 Modification factor for anchor groups loaded eccentrically in shear , ψ ec , V , shall be calculated by Eq . ( 17.7.2.3.1 ).
ψ ec , V
=
1 e ́V 1 +
1.5c a1
≤ 1.0 ( 17.7.2.3.1 )
17.7.2.3 . 2 If the loading on an anchor group is such that only some of the anchors in the group are in shear , only those anchors that are in shear in the same direction shall be considered for determining the eccentricity e ́V in Eq . ( 17.7.2.3.1 ) and for the calculation of V cbg according to Eq .
( 17.7.2.1b ).
e ́V is an ACI 318 parameter to define shear eccentricity . PROFIS Engineering designates this parameter “ e c , V
”. The value for e ́V corresponds the distance of a resultant shear load from the centroid of anchors that are loaded in shear . Shear eccentricity is used to calculate the ACI 318 modification factor for shear eccentricity ( ψ ec , V
). PROFIS Engineering calculations for shear eccentricity are as follows :
• calculate a resultant shear load acting on the anchors .
• calculate the distance ( e ́V ) between this load and the centroid of the anchors loaded in shear .
• calculate the modification factor for shear eccentricity ( ψ e , V
).
If a torsion moment acts on the anchorage , the direction of the shear load acting on individual anchors will vary . Below is an illustration showing how PROFIS Engineering accounts for shear eccentricity when a torsion moment acts on the anchorage .
V s
= V 2 , x + V 4 , x
V y
= V 3 , y + V 4 , y
➞ V ua , g = ( V x
) 2 + ( V y
) 2 tan -1 θ =
( sin θ )
Reference the Variables section of the PROFIS Engineering report for more information on the parameter c a1
.
Reference the Calculations section of the PROFIS Engineering report for more information on the parameter ψ ec , V
.
180 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions