Page 83 - Design of Reinforced Masonry Structures

2.36 CHAPTER TWO

Techniques of obtaining bond in brick and masonry are essentially similar. However,
differences exist because of the differences in the manner in which walls are constructed
with clay masonry units (bricks) and concrete masonry units. Brick walls may be single
wythe or multiwythe, whereas a wall built using concrete masonry units would usually be
single wythe.

2.7.2 Bonds in Clay Masonry (Brick) Walls

All types of masonry units are placed together—one above the other, or side-by-side—with
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mortar joints between them, which is usually ⁄ 8 in. wide. Brick units can be laid in various
positions: on the face or on the edge; the long dimension may be kept vertical or horizontal
(parallel or perpendicular to wall face). These various positions are known as stretcher,
header, soldier, shiner, rowlock or sailor (Fig. 2.4). Each layer of masonry units is called a
course. The units can be arranged in courses in several ways. They may be laid in (a) regular
courses of the same height, (b) in courses of two or more different heights, or (c) several
sizes of units may be laid in a prearranged pattern. Within the same course in a two-wythe
brick wall, the units can be laid (positioned) as headers or stretchers (Fig. 2.4).
A course consisting of units overlapping more than one wythe of masonry is called a
bond course. Over the height of wall, the units can be placed so that the vertical joints are
either continuous or discontinuous, resulting in many different kinds of appearances called
pattern bonds. A comprehensive discussion on various types for brick masonry walls is
presented in Ref. [2.48], which is summarized here.
Structural bonding of brick masonry walls is obtained in three ways:
1. By the overlapping (interlocking) of the
masonry units,
2. By the use of metal ties embedded in
connecting joints, and
3. By the adhesion of grout to adjacent
wythes of masonry.
Traditionally, brick walls have been built
with two types of overlapped bonds: English
bond and Flemish bond (Fig. 2.34); other
overlapped bonds are based on their varia-
tions. The English bond consists of alternat-
ing courses of headers and stretchers. The
headers are centered on the stretchers and
joints between stretchers in all courses are
aligned vertically. By contrast, the Flemish
bond consists of alternating courses of
headers and stretchers in every course, so
arranged that the headers and stretchers in
every other course align vertically. In both
cases, the stretchers, laid with the length
of the wall develop longitudinal bonding,
whereas the headers, laid across the width
of the wall, bond the wall transversely.
Building codes require that masonry bonded
FIGURE 2.34 English and Flemish bonds. brick walls be bonded so that not less than
(Courtesy: BIA.) 4 percent of the wall surface is composed