Capacity of Simpson RP6, CMU Wall To Roof Anchor

[fprimec]

Hey Everyone,

Long time lurker, first time poster.

I am looking for some guidance on the capacity of the Simpson RP6. This is a retro fit plate to tie the CMU wall to the roof framing. This is off the shelf but I assume evry old building got retrofitted with a version of these plates back in the day.

Does anyone know the capacity of this anchor? I assume it is going to be CMU wall dependent. I have a 4x16x12 CMU wall built in the 1960's that I need to retrofit. This is in Los Angeles, trying to meet CH 96 LABC. The Simpson Wood Connector Catalog does not list a capacity. The code reference is PR, which says it meets prescriptive requirements.

https://www.strongtie.com/holdowns_holdownsandtensionties/rp_plate/p/rp6

C-C-2024_p048-049.pdf

ssttoolbox.widen.net

Did people just trust the anchors will hold?

Due to the LABC requirements I need to make symmetrically spaced to the framing member to avoid eccentric loading to members. So I am trying to understand the mechanics behind it to see if there are any reduction in strength that I should take.

The masonry design book says to take masonry shear breakout to Bvnb = 1.25* Apv *sqrt(f'm) (ASD) & Bvnb = 4* Apv *sqrt(f'm) (LRFD) with a phi = 0.5.

An embedded anchor would have a Apv = Pi() * Lb^2 where Lb is the anchor embedded length in the grouted CMU.

Any help or guidance would be appreciated from the wise minds on this forum.
-FprimeC

 

[phamENG]

Really, these are just conveniently fabricated plates to use - order them from Simpson and (hopefully) save a little over having a shop custom cut and drill each one. Capacity would be based on the lesser of yielding of the plate and bearing stress on the masonry.