Masonry Magazine April 1992 Page. 28
ceed 24 in. (610 mm), and the maximum horizontal dis-
tance should not exceed 36 in. (914 mm). Z-ties may
not be used with hollow masonry units. Additional
metal ties should be provided at all openings, spaced
not more than 3 ft (0.91 m) apart around the perimeter
and within 12 in. (300 mm) of the opening. These pro-
visions are similar to those for cavity wall construction.
When bonding multi-wythe walls with horizontal
joint reinforcement, there should be one crosswire met-
al tie for each 2% ft² (0.25 m²) of wall area. The verti-
cal spacing should not exceed 16 in. (400 mm). Cross-
wires should not be smaller than No. 9 gage wire (W
1.7) and be corrosion resistant.
Pattern Bond. Masonry walls can be laid in either
running or stack bond. Running bond is defined by
each wythe of masonry head joints in successive cours-
es being offset by at least one-quarter the unit length
(see Fig. 4). It is considered stack bond if the longitu-
dinal bond is offset less than one-quarter the unit
length, and horizontal joint reinforcement or bond
beams with a maximum spacing of 4 ft (1.2 m) vertical-
ly with a minimum area of steel equal to 0.0003 times
the vertical cross-sectional area of the wall must be pro-
vided.
Anchorage (9.8)
Masonry elements must be anchored to various com-
ponents of the building which provide lateral support
when using empirical design. Anchorage must occur at
intersecting walls, at floors and roofs which adjoin ma-
sonry walls and where masonry walls abut structural
framing. Anchorage requirements for masonry walls
contained in ACI 530/ASCE 5 are as follows:
9.8.2 Intersecting walls Masonry walls depend-
ing upon one another for lateral support shall be an-
chored or bonded at locations where they meet or in-
tersect by one of the following methods:
9.8.2.1 Fifty percent of the units at the intersec-
tion shall be laid in an overlapping masonry
bonding pattern, with alternate units having a
bearing of not less than 3 in. (75 mm) on the unit
below.
9.8.2.2 Walls should be anchored by steel connec
tors having a minimum section of % in. (6.4 mm) by
1% in. (38.1 mm) with ends bent up at least 2 in. (50
mm) or with cross pins to form anchorage. Such
anchors shall be at least 24 in. (600 mm) long and
the maximum spacing shall be 4 ft (1.22 m).
TYPICAL RUNNING BOND MASONRY
(HALF BOND)
UNIT OVERLAP,
MINIMUM
Running Bond Masonry
FIG. 4
6