Hello,
I am trying to perform some punching shear checks using RAM Concept, however, I am noticing that the program does not reduce the punch perimeter when there is an opening <10h away from column CL. According to ACI 318-14 Section 22.6.4.3, there should be some reduction in the punching perimeter which is a function of the distance to the opening and the opening dimensions. Auditing the punch section, there is no reduction in the punch perimeter. I have selected the "Edge Condition" as "Sector Voids", so I am not sure why RAM is not accounting for openings in its punch check.
Please let me know what you think.
Make sure the punching check perimeter is large enough to capture the entire failure plane. It could be that the smaller section just controls. You can plot all the evaluated failure planes on the stress plan.
Seth, yes the punching check has been drawn to be big enough to capture all the openings. Even if the smaller section controls, there should be a reduction in the smaller perimeter. Please see below for images showing the punch perimeter drawn in the program and then an image from code section 22.6.4.3.2 showing the reduction I'm talking about graphically.
The opening was considered, you can see the failure plane in the figure on the left. It has a tiny bit missing at the corner of the opening.
Seth, it is graphically in the punching checks plan but when you look at the punching stresses plan and audit the section, it does not graphically nor numerically show this reduction. i can see your confusion from the image i provided, so please see below for screenshots of the stress perimeter and screenshots from the audit section window.
For reference, the column is 24x24 (c = 24") and on an 11" slab with d = 9.375"
So, for a square column, the interior punch perimeter would be (c+d)*4 = 133.5" - I would expect RAM to report a perimeter < than 133.5", as you can see in my screenshot below, the perimeter RAM reports for its first iteration (and the smallest perimeter) in this report is exactly 133.5".
It sounds like you want the method of sector voids which would "take a bite out" of the perimeter even though the opening is beyond the failure plane. You'll need an extra large punching check radius to see the full opening (the circle should encompass the far corners ideally), and probably some extra section sections per zone. You'll also need to use the plot settings to show all four sections.