Masonry Magazine August 1987 Page. 21
Proprietary Anchor Bolts
Proprietary anchors are available through a number of manufacturers under numerous brand names. Although the style and physical appearance of the anchors differ between manufacturers, the basic theories behind the anchors are very similar. For this reason, proprietary anchors can be divided into two generic categories: expansion-type anchors and adhesive or chemical-type anchors.
Expansion Anchors
Two different types of expansion anchors are generally recommended by their manufacturers for use in brick masonry: the wedge anchor and the sleeve anchor (see Fig. 7). These anchors develop their strength by means of expansion into the base material. Wedge anchors develop their hold by means of a wedge or wedges that are forced into the base material when the bolt is tightened. The wedges create large point bearing stresses within the hole; therefore, this anchor requires a solid base material to develop its full capacity. For this reason, voids formed by brick cores and partially filled mortar joints in some brick masonry may make the construction unsuitable for wedge anchor installation.
Proprietary Expansion Anchors
Sleeve anchors develop their strength by the expansion of a cylindrical metal sleeve or shield into the base material as the bolt is tightened. The expansion of the sleeve along the length of the anchor provides a larger bearing surface than the wedge anchor, and is less affected by irregularities and voids in the base material than is the wedge anchor. For this reason, sleeve anchors are recommended by their manufacturers for use in brick masonry more often than wedge anchors.
Drop-in and self-drilling anchors (see Fig. 8) are two other types of expansion anchors available, but are typically not recommended by their manufacturers for use in masonry. The reason for this is due to the embedment and setting characteristics of the two anchors. Both anchors are produced to allow shallow embedment depths and are expanded or set by an impact setting tool. The combination of shallow embedment and high stresses imparted by the expansion tend to cause cracking or splitting in masonry. Depending on the extent of cracking or splitting, the anchor could experience a reduction in load-carrying capacity or undergo complete failure during installation.
Through Bolt
FIG. 5
TABLE 1
AISC Fillet Weld Size Requirements
Minimum Size
Material Thickness of
Thicker Part Joined
Minimum Leg
Dimensions
In.
In.
To 1/4 Inclusive
1/8
Over 1/4 to 1/2
3/16
Over 1/2 to 3/4
1/4
Over 3/4
5/16
Maximum Size
1. Along edges of material less than 1/4 in. thick, not greater than the thickness of the material.
2. Along the edges of material 1/4 in. or more in thickness, not greater than the thickness of the material minus 1/16 in., unless the weld is especially designated on the drawing to be built out to obtain full throat thickness.
American Institute of Steel Construction
Decorative Through Bolt Bearing Plate
FIG. 6
A) WEDGE ANCHOR
B) SLEEVE ANCHOR
FIG. 7
3