TRUSS. a truss is a structure comprising one or more triangular units which are constructed with straight slender members whose ends are connected at joints.

A plane truss is one where all the members and joints lie within a 2-dimensional plane, while a space truss has members and joints extending into 3 dimensions.

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.

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