PART 4 SHEAR LOAD
Pryout Failure Mode ( Pryout Bond )
Variables e c2 , N
Variables 318-14 Chapter 17 Provision Comments for PROFIS Engineering
e c2 , N
17.4.5.3 The modification factor for adhesive anchor groups loaded eccentrically in tension , ψ ec , Na shall be calculated as : ψ ec , Na
= but ψ ec , Na shall not be taken greater than 1.0 .
1
1 + e ́N c Na
( 17.4.5.3 )
If the loading on an adhesive anchor group is such that only some adhesive anchors are in tension , only those adhesive anchors that are in tension shall be considered when determining the eccentricity e ́N for use in Eq . ( 17.4.5.3 ) and for the calculation of N ag according to Eq . ( 17.4.5.1b ). In the case where eccentric loading exists about two orthogonal axes , the modification factor ,
ψ ec , Na
, shall be calculated for each axis individually and the product of these factors used as ψ ec , Na in Eq . ( 17.4.5.1b ). e c2 , N is a PROFIS Engineering parameter to define pryout eccentricity with respect to the y direction . The value for e c2 , N corresponds the distance in the y direction of a resultant shear load from the centroid of anchors that are loaded in shear . When considering concrete pryout strength in shear , PROFIS Engineering uses e c2 , N to calculate the ACI 318 modification factor for eccentricity ( ψ ec , N ), and designates this modification factor ψ ec2 , N to indicate eccentricity is being considered in the y direction . PROFIS Engineering pryout calculations for shear eccentricity with respect to the y direction are as follows :
• Calculate a resultant shear load acting on the anchors .
• Calculate the distance in the y direction ( e c2 , N
) between this load and the centroid of the anchors loaded in shear .
• Calculate a modification factor for eccentricity ( ψ ec2 , N ) with respect to the y direction .
If the resultant shear load acting on the anchorage is eccentric with respect to both the x and y directions ; PROFIS Engineering calculates the eccentricity for each direction ( e c1 , N with respect to the x direction and e c2 , N with respect to the y direction ), and the ψ ec , N modification factor for each direction ( ψ ec1 , N for eccentricity with respect to the x direction and ψ ec2 , N for eccentricity with respect to the y direction ). ψ ec1 , N and ψ ec2 , N are multiplied together to give a total modification factor for pryout eccentricity .
The illustration below shows how PROFIS Engineering considers shear eccentricity when calculating V cpg
. The resultant shear load ( V res
) is eccentric in both the x direction and y direction with respect to the centroid of the anchors that are in shear . PROFIS Engineering defines the eccentricity of the shear load in the x-direction as the parameter “ e c1 , N
” and eccentricity in the y-direction as the parameter “ e c2 , N
”.
Reference the Variables section of the PROFIS Engineering report for more information on :
e c1 , N
: Parameter for pryout eccentricity with respect to the x direction
227 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions