Figure 3-2.Structural shapes.
the S-shape is in the design of the inner surfaces of the
flange. The W-shape has parallel inner and outer
flange surfaces with a constant thickness, while the
S-shape has a slope of approximately 17 on the inner
flange surfaces. The C-shape is similar to the S-shape
in that its inner flange surface is also sloped
The W-SHAPE is a structural member whose
cross section forms the letter H and is the most widely
used structural member. It is designed so that its
flanges provide strength in a horizontal plane, while
the web gives strength in a vertical plane. W-shapes
are used as beams, columns, truss members, and in
other load-bearing applications.
The BEARING PILE (HP-shape) is almost
identical to the W-shape. The only difference is that
the flange thickness and web thickness of the bearing
pile are equal, whereas the W-shape has different web
and flange thicknesses.
The S-SHAPE (American Standard I-beam) is
distinguished by its cross section being shaped like the
letter I. S-shapes are used less frequently than
W-shapes since the S-shapes possess less strength and
are less adaptable than W-shapes.
The C-SHAPE (American Standard channel) has
a cross section somewhat similar to the letter C. It is
especially useful in locations where a single flat face
without outstanding flanges on one side is required.
The C-shape is not very efficient for a beam or column
when used alone. However, efficient built-up
members may be constructed of channels assembled
together with other structural shapes and connected by
rivets or welds.
An ANGLE is a structural shape whose cross
section resembles the letter L. Two types, as illustrated
in figure 3-3, are commonly used: an equal-leg angle
and an unequal-leg angle. The angle is identified by
the dimension and thickness of its legs; for example,
angle 6 inches x 4 inches x 1/2 inch. The dimension
of the legs should be obtained by measuring along the
outside of the backs of the legs. When an angle has
unequal legs, the dimension of the wider leg is given
first, as in the example just cited. The third dimension
applies to the thickness of the legs, which al ways have
equal thickness. Angles may be used in combinations
of two or four to form main members. A single angle
may also be used to connect main parts together.
Steel PLATE is a structural shape whose cross
section is in the form of a flat rectangle. Generally, a
main point to remember about plate is that it has a
width of greater than 8 inches and a thickness of 1/4
inch or greater.
Plates are generally used as connections between
other structural members or as component parts of
built-up structural members. Plates cut to specific
sizes may be obtained in widths ranging from 8 inches
to 120 inches or more, and in various thicknesses. The
edges of these plates may be cut by shears (sheared
plates) or be rolled square (universal mill plates).
Plates frequently are referred to by their thickness
and width in inches, as plate 1/2 inch x 24 inches. The
length in all cases is given in inches. Note in figure 3-4
that 1 cubic foot of steel weighs 490 pounds. his
weight divided by 12 gives you 40.8, which is the
weight (in pounds) of a steel plate 1 foot square and 1
inch thick The fractional portion is normally dropped
and 1-inch plate is called a 40-pound plate. In practice,
you may hear plate referred to by its approximate
weight per square foot for a specified thickness. An
example is 20-pound plate, which indicates a 1/2-inch
plate. (See figure 3-4.)
The designations generally used for flat steel have
been established by the American Iron and Steel
Institute (AISI). Flat steel is designated as bar, strip,