Page 87 - Masonry and Concrete

Understanding Masonry
86 CHAPTER FOUR

multifamily housing or closely built single-family homes or town-
houses. It is durable enough against wear and abrasion to serve as a
paving material, and most types of masonry weather very well without
any kind of protective coating. Masonry can provide efficient thermal
and acoustical resistance, and when it is properly designed and con-
structed to meet current building codes, masonry is also resistant to
earthquakes. In both the Loma Prieta and Northridge earthquakes in
California, building officials documented the excellent performance of
properly designed masonry in resisting significant seismic loads. The
same is true for hurricane winds. When properly designed and con-
structed according to current building code requirements, even south
Florida’s Hurricane Andrew had little damaging effect on masonry
structures. Almost any masonry material or combination of materials
can be used to satisfy many different functional requirements, but spe-
cific masonry materials are usually selected on the basis of aesthetic
criteria such as color, texture, and scale.
Like all building materials, masonry expands and contracts with
changes in temperature, but masonry is relatively stable compared to
metals and plastics. Concrete, masonry, and wood also expand and
contract with changes in moisture content. Flexible anchorage, rein-
forcement, control joints, and expansion joints are used to accommo-
date the combined effects of thermal and moisture movements so that
the masonry will not crack. Expansion, contraction, and weather resis-
tance are discussed in more detail later in this chapter.

LOAD LOAD LOAD

COMPRESSION
WEAK
STRONG
WEAK
TENSION
CRACK
LOAD LOAD

COMPRESSION TENSION FLEXURE
FIGURE 4-2

Tension and compression in masonry.

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