Masonry Magazine August 1987 Page. 27
Masonry Capacity
Thus, the area Ap, in Eq. 1 will be the lesser of:
Ap = π 1b2 (Eq. 3)
or
Ap = π 1be2 (Eq. 4)
where:
Ap= Projected area of the masonry tension cone, in.2,
1b = Effective embedded anchor length, in.,
1be = Distance to a free edge, in.
The effective anchor embedded length (1b) is the length of embedment measured perpendicular from the surface of the masonry to the plate or head for plate anchors or headed bolts. The effective embedded length of bent bar bolts (1) is the length of embedment measured perpendicular from the surface of the masonry to the bearing surface of the bent end minus one bolt diameter. Where the projected areas of adjacent anchors overlap, Ap of each bolt is reduced by one-half of the overlap area. Also, any portion of the projected cone falling across an opening in the masonry (i.e., holes for pipes or conduits) should be deducted from the value of Ap calculated in Eqs. 3 or 4.
Shear
The allowable shear load is based on the same logic as the allowable tension load. That is, the anchor capacity is governed by either the masonry strength or the anchor material strength. The distance between an anchor and a free masonry edge has an effect on the masonry shear capacity. Calculations have shown that for edge distances less than twelve times the anchor diameter, the masonry shear strength controls the anchor capacity. Therefore, where the edge distance equals or exceeds 12 anchor diameters, the allowable shear load is the lesser of:
VA = 350 √f'm AB (Eq. 5)
or
VA = 0.12 Apfy (Eq. 6)
where:
VA = Allowable shear load, lb.
Calculations based on masonry with f'm = 1000 psi and anchor steel yield strength with fy = 60 ksi.