I am assessing an anchor solution for an electrical cabinet that is ~142" x 20". I have used 8 anchors, with four spaced evenly along each long side. This solution does not pass the ACI 318-19 assessment due to concrete breakout. If I double the number of anchors (eight along each long edge) then it is a similar failure. If I keep eight anchors, but reduce the lateral spacing between them, then the assessment passes. This seems unintuitive and I'd welcome some feedback (or learning opportunity!). Many thanks
Thanks for the enquiry, apologies over the delay in response as it’s not a code that is frequently used in this area of Europe. The differences between the two designs has to do with how PROFIS Engineering is determining the
neutral axis based on the loading, baseplate layout, and anchor layout. If you reference section 3.2 Concrete Breakout Failure for both reports, you will see the differences between ec1,N and ec2,N on both designs where ec1,N and ec2,N represent the distance from the centroid of the anchors loaded in tension to the resultant force in both x and y
directions, see snippet below from Figure R17.6.2.3.1 of ACI 318-19 for more information.
These variables are then used to calculate the modification factor for breakout eccentricity which is Eq. 17.6.2.3.1 of ACI 318-19. The smaller the modification factor, the more significant of an impact that is applied to the concrete breakout capacity.
As a separate note the anchors on your file I believe are not available within Europe
