Page 35 - Design of Reinforced Masonry Structures

1.4 CHAPTER ONE

present-day engineered-masonry construction, which uses methods completely different
from the empirical methods of the past. What once evolved as merely masons’ creations
came to be designed and built as engineered structures.
Reinforced masonry construction as we know it today is rather recent. The principles
of reinforced masonry construction are said to have been discovered by Marc Isambard
Brunel, once a chief engineer for New York City, a great innovator, and one of the greatest
engineers of his time. In 1813, he first proposed the use of reinforced brick masonry as a
means of strengthening a chimney then under construction. However, his first major appli-
cation of reinforced masonry was in connection with the building of the Thames Tunnel in
1825. As a part of this construction project, two brick shafts were built, each 30 in. thick,
50 ft in diameter, and 70 ft deep. These shafts were reinforced vertically with 1-in.-diameter
wrought iron rods, built into the brickwork. Iron hoops, 9 in. wide and ½ in. thick, were laid
in the brickwork as the construction progressed [1.15]. Continuing his work with reinforced
brick masonry, Brunel, in 1836, constructed test structures in an effort to determine the
additional strength contributed to the masonry by the reinforcement.
The credit for the modern development of reinforced brick masonry is generally given
to A. Brebner, once an Under Secretary in the Public Works Department, Government of
India, who conducted pioneering research on reinforced brick. In his report of extensive
tests on reinforced brick masonry conducted over a two-year period and published in 1923
2
[1.16], Brebner stated that “nearly 3,000,000 ft have been laid in the last three years.” Thus
began the era of reinforced brick construction. Reinforced brickwork was quickly followed
in Japan. Skigeyuki Kanamori, Civil Engineer, Department of Home Affairs, Imperial
Japanese Government, is reported to have stated [1.17]:

There is no question that reinforced brickwork should be used instead of (unreinforced) brick-
work when any tensile stress would be incurred in the structure. We can make them safer and
stronger, saving much cost. Further I have found that reinforced brickwork is more convenient
and economical in building than reinforced concrete and, what is still more important, there is
always a very appreciable saving in time.

Structures designed by Kanamori
include sea walls, culverts, and railways
retaining walls, as well as buildings [1.18].
Research on brick construction in
the United States is credited to the work
undertaken by the Brick Manufacturers
Association of America and continued
by the Structural Clay Products Institute
and the Structural Clay Products Research
Foundation (SCR). This research effort
generated much valuable information
on various aspects of reinforced brick
masonry. Since 1924, numerous field and
laboratory tests have been made on rein-
forced brick beams, slabs, columns, and
on full-size structures. Figure 1.1 shows
an example of a 1936 test to demonstrate
the structural capabilities of reinforced
brick elements [1.18].
Concrete block masonry units (often
FIGURE 1.1 Early test of reinforced concrete referred to as CMU) were developed by
brick masonry element [1.10]. the construction industry in the 1930s. Use