Annex D - Anchor subject to shear, parallel vs in a corner

[wrigleys]

Hi, I would like to know when an anchor or anchor group are considered parallel to an edge or in a corner. This is for equation D-30 and D-31 in ACI 318-11 for concrete breakout strenght of anchor in shear. Do I have to check both and take the lowest value ?

 

[sbouvia]

You ask two questions in this post, and here are what I am thinking for answers;

An anchor/anchor group would be influenced by an edge or a corner when the distance between the anchor and the corner/edge is less than 1.5*ca1 where ca1 is the distance from the loaded anchor with the shear force to the edge of the concrete. Reference Figure RD.6.2.1.

For anchors with the shear load parallel to the edge (think of a wall plate with a vertical load near the edge of a wall, or an embed plate on a column) you are allowed to use twice the value obtained from equations D-30 and D-31 with the force assumed to act perpendicular to the edge. I would read the commentary section RD.6.2.1(b) to determine which case you should analyze, as there are 3 possible cases, however if your connectors can be assumed to be rigidly attached to the plate only Case 2 applies.

Hope this helps,

Scott B.