In bridge construction, a pier is a vertical member that
provides intermediate support for the bridge
The chief vertical structural members in
light-frame construction are called studs (see figures
2-1 and 2-3). They are supported by horizontal
members called sills or soleplates, as shown in
figure 2-3. Corner posts are enlarged studs located at
the building corners.
Formerly, in full-frame
construction, a corner post was usually a solid piece
of larger timber.
In most modern construction,
though, built-up corner posts are used. These consist
of various members of ordinary studs nailed together
in various ways.
HORIZONTAL STRUCTURAL MEMBERS
Technically, any horizontal load-bearing
structural member that spans a space and is supported
at both ends is considered a beam. A member fixed at
one end only is called a cantilever. Steel members that
consist of solid pieces of regular structural steel are
referred to as structural shapes. A girder (shown in
figure 2-2) is a structural shape. Other prefabricated,
open-web, structural-steel shapes are called bar joists
(also shown in figure 2-2).
Horizontal structural members that support the
ends of floor beams or joists in wood-frame
construction are called sills or girders see figures 2-1
and 2-3). The name used depends on the type of
framing and the location of the member in the
structure. Horizontal members that support studs are
called soleplates, depending on the type of framing.
Horizontal members that support the wall ends of
rafters are called rafter plates. Horizontal members
that assume the weight of concrete or masonry walls
above door and window openings are called lintels
The horizontal or inclined members that provide
support to a roof are called rafters (figure 2-1). The
lengthwise (right angle to the rafters) member, which
supports the peak ends of the rafters in a roof, is called
the ridge. The ridge may be called a ridge board, the
ridge piece, or the ridge pole. Lengthwise members
other than ridges are called purlins. In wood-frame
construction, the wall ends of rafters are supported on
horizontal members called rafter plates, which are, in
turn, supported by the outside wall studs. In concrete
or masonry wall construction, the wall ends of rafters
may be anchored directly on the walls or on plates
bolted to the walls.
A beam of given strength, without intermediate
supports below, can support a given load over only a
specific maximum span. When the span is wider than
this maximum space, intermediate supports, such as
columns, must be provided for the beam. Sometimes
it is either not feasible or impossible to increase the
beam size or to install intermediate supports. In such
cases, a truss is used. A truss is a combination of
members, such as beams, bars, and ties, usually
arranged in triangular units to form a rigid framework
for supporting loads over a span.
The basic components of a roof truss are the top
and bottom chords and the web members. The top
chords serve as roof rafters. The bottom chords act as
ceiling joists. The web members run between the top
and bottom chords. The truss parts are usually made
of 2- by 4-inch or 2- by 6-inch material and are tied
together with metal or plywood gusset plates, as
shown in figure 2-4.
Roof trusses come in a variety of shapes and
sizes. The most commonly used roof trusses, shown
in figure 2-5, for light-frame construction are the
king-post, the W-type, and the scissors trusses. The
simplest type of truss used in frame construction is the
king-post truss. It is mainly used for spans up to 22
feet. The most widely used truss in light-frame
construction is the W-type truss. The W-type truss
can be placed over spans up to 50 feet. The scissors
truss is used for buildings with sloping ceilings.
Generally, the slope of the bottom chord equals
one-half the slope of the top chord. It can be placed
over spans up to 50 feet.
LEARNING OBJECTIVE: Upon completing
this section, you should be able to recognize
the different types of drawings and their uses.
The building of any structure is described by a set
of related drawings that give the Builder a complete,
sequential, graphic description of each phase of the
construction process. In most cases, a set of drawings
begins by showing the location, boundaries, contours,
and outstanding physical features of the construction
site and its adjoining areas. Succeeding drawings
give instructions for the excavation and disposition of
existing ground; construction of the foundations and
superstructure; installation of utilities, such as
plumbing, heating, lighting, air conditioning, interior
and exterior finishes; and whatever else is required to
complete the structure.