Masonry Magazine August 1987 Page. 26
Tension
The tensile capacity of an anchor is governed either by the strength of the masonry or by the strength of the anchor material. For example, if the embedded depth of an anchor is small relative to its diameter, a tension cone failure of the masonry is likely to occur. However, if the embedded depth of the anchor is large relative to its diameter, failure of the anchor material is likely. For these reasons, the allowable tensile load is based on the smaller of the two loads calculated for the masonry and anchor material. Thus, the allowable load in tension is the lesser of:
TA = ½ Ap √f'm (Eq. 1)
or
TA = 0.2 Anfy (Eq. 2)
where:
TA = Allowable tensile load, lb,
Ap = Projected area of the masonry tension cone, in.2,
f'm = Masonry prism compression strength', psi,
AB = Anchor gross cross-sectional area, in.2,
fy = Anchor steel yield strength, psi.
The value of Ap in Eq. 1 is the area of a circle formed by a failure surface (masonry cone) assumed to radiate at an angle of 45° (see Fig. 19) from the anchor base. When an anchor is embedded close to a free edge, as shown in Fig. 20, a full masonry cone cannot be developed and the area Ap must be reduced so as not to over-estimate the
In composite construction, when the masonry cone intersects different materials, f should be based on the weaker material.
A) GROUTED COLLAR JOINT CONSTRUCTION
B) MULTI-WYTHE BRICK CONSTRUCTION
C) GROUTED HOLLOW BRICK
Typical Proprietary Anchor Details
FIG. 18