Figure 1-46.—Completed 40' x 100' x 14' preengineered metal building.
Figure 1-47.—Structural members of a preengineered metal building.
Again, a lateral bracing system is used between the
trusses. The pony truss span is the same as that
discussed in the preceding paragragh. Because of the
small depth of the trusses, no top lateral bracing is used.
Towers
Towers are framework structures designed to
provide vertical support. They may be used to support
another structure, such as a bridge, or they may be used
to support a piece of equipment, such as a communi-
cation antenna. Since the prime purpose of a tower is to
provide vertical support for a load applied at the top, the
compression members providing this support are the
only ones that require high-structural strength. The rest
of the structure is designed to stiffen the vertical
members and to prevent bending under load. Primarily,
the bracing members are designed to take loads in
tension and are based on a series of diagonals. A typical
trestle tower used in bridge construction is shown in
figure 1-45.
Preengineered Metal Structures
Preengineered metal structures are commonly used
in military construction. These structures are usually
designed and fabricated by civilian industry to conform
with specifications set forth by the military. Rigid frame
buildings, steel towers, communications antennas, and
steel tanks are some of the most commonly used
structures, particularly at overseas advanced bases.
Prerengineered structures offer an advantage in that they
are factory built and designed to be erected in the
shortest amount of time possible. Each structure is
shipped as a complete kit, including all the materials and
instructions needed to erect it.
Of the preengineered metal structures available, the
one that is perhaps most familiar to the Seabees is the
preengineered metal building (PEB) shown in figures
1-46 and 1-47. Figure 1-47 shows the nomenclature of
the various parts of the PEB. For definition of this
nomenclature, erection details, and other important
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