TYPES. A metal plate-connected wood truss is a
roof or floor truss whose wood members are connected with
metal connector plates. There are two basic types of trusses.
The pitched truss or common truss is characterized by its
triangular shape. It is most often used for roof construction.
Some common trusses are named according to their web configuration.
The chord size and web configuration are determined by span,
load and spacing. The parallel chord truss or flat truss
gets its name from its parallel top and bottom chords. It
is often used for floor construction. A combination of the
two is a truncated truss, used in hip roof construction.
Vierendeel truss. A
special truss is the Vierendeel truss, named after
the Belgian engineer Arthur Vierendeel, who developed the
design in 1896. The Vierendeel truss is a truss
where the members are not triangulated but form rectangular
openings, and is a frame with fixed joints that are capable
of transferring and resisting bending moments. In this statically
indeterminate structure the individual horizontal and vertical
members are designed as beams. Diagonal bracing is omitted
as the joints are designed to withstand the moments that
occur at the ends of the members. Trusses of this type are
used in some bridges (see Vierendeel bridge), and were also
used in the frame of the Twin Towers of the World Trade
Center. By eliminating diagonal members, the creation of
rectangular openings for windows and doors is simplified,
since this truss can reduce or eliminate the need for compensating
shear walls.
King
Post Truss. One of the simplest truss
styles to implement, the king post consists of two angled
supports leaning into a common vertical support. Force that
is applied to the structure from any angle is appreciably
distributed between the component supports.
Queen
Post Truss. The queen post truss, sometimes
queenpost or queenspost, is similar to a king
post truss in that the outer supports are angled towards
the center of the structure. The primary difference is the
horizontal keystone-like support that extends the
span of the king post. This truss style is only suitable
for short spans.