The "wood engineering" forum is probably not a good place for this question. You should try "structural engineering other topics" or even "ACI Code". You will probably get more results. Since you're already here, reinforced masonry shear strength is based on sqrt(f'm) or some modification of that per ACI 530, if that's the code you are using. You just need the f'm or assume the minimum f'm applicable to find the shear strength of the masonry as a whole.
