1.0 TENSION
1.1 Bond Failure Mode
Calculations ψ ec1 , Na
( continued )
Calculations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
ψ ec1 , Na
Reference the Variables section of the PROFIS Engineering report for more information on :
e c1 , N
: parameter for tension eccentricity with respect to the x direction .
Reference the Variables section of the PROFIS Engineering report for more information on :
e c2 , N
: parameter for tension eccentricity with respect to the y direction .
Reference the Equations section of the PROFIS Engineering report for more information on :
ψ ec1 , Na
: modification factor for tension eccentricity with respect to the x direction .
Reference the Equations section of the PROFIS Engineering report for more information on :
ψ ec2 , Na
: modification factor for tension eccentricity with respect to the y direction .
Calculations ψ ec2 , Na
Calculations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
ψ ec2 , Na
17.6.5.3.1 Modification factor for adhesive anchor groups loaded eccentrically in tension , ψec , Na shall be calculated by Eq . ( 17.6.5.3.1 ).
ψ ec , Na
=
1
1 + e ́N c Na
( 17.6.5.3.1 )
17.6.5.3.2 If the loading on an adhesive anchor group is such that only some of the adhesive anchors are in tension , only those adhesive anchors that are in tension shall be considered for determining the eccentricity e ́N in Eq . ( 17.6.5.3.1 ) and for the calculation of N ag according to Eq .
( 17.6.5.1b ). 17.6.5.3.3 If a load is eccentric about two orthogonal axes , ψ ec , N a shall be calculated for each axis individually , and the product of these factors shall be used as ψ ec , Na in Eq . ( 17.6.5.1b ).
When calculating nominal bond strength for a group of adhesive anchors in tension ( N ag
), ACI 318 anchoring-to-concrete provisions designate the modification factor for tension eccentricity “ ψ ec , Na
”. Per Section 17.6.5.3.3 , tension eccentricity can be considered with respect to the x and y directions . PROFIS Engineering designates the modification factor for tension eccentricity in the y direction “ ψ ec2 , Na
”. The parameter e c2 , N is a PROFIS Engineering parameter to define tension eccentricity with respect to the y direction using Eq . ( 17.6.5.3.1 ). PROFIS Engineering calculations for tension eccentricity with respect to the y direction are as follows :
• calculate a resultant tension 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 tension .
• calculate a modification factor for tension eccentricity ( ψ ec2 , Na ) with respect to the y direction .
If the resultant tension 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 , Na for eccentricity with respect to the x direction and ψ ec2 , Na for eccentricity with respect to the y direction ). ψ ec1 , Na and ψ ec2 , Na are multiplied together to give a total modification factor for eccentricity per ACI 318-19 Section 17.6.5.3.3 .
35 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions