PROFIS ENGINEERING REPORT TENSION LOAD
Bond Failure Mode
Variables e c1 , N
Variables ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering
e c1 , 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 c1 , N is a PROFIS Engineering parameter to define tension eccentricity with respect to the x direction . The value for e c1 , N corresponds to the distance in the x direction of a resultant tension load from the centroid of anchors that are loaded in tension . PROFIS Engineering uses e c1 , N to calculate the ACI 318 modification factor for tension eccentricity ( ψ ec , Na ), and designates this modification factor ψ ec1 , Na to indicate eccentricity is being considered in the x direction . PROFIS Engineering calculations for tension eccentricity with respect to the x direction are as follows :
• Calculate a resultant tension load acting on the anchors
• Calculate the distance in the x direction ( e c1 , N
) between this load and the centroid of the anchors loaded in tension
• Calculate a modification factor for tension eccentricity ( ψ ec1 , Na ) with respect to the x 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 318-14 Section 17.4.5.3
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
Below is an illustration showing how PROFIS Engineering accounts for eccentricity with respect to the x direction when calculating bond strength in tension .
ψ ec1 , Na
=
1
1 + 2 . 75 ” = 0.795 10.65 ”
25 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions