King-post truss

A king post is a central vertical supporting post used in architectural, bridge or aircraft design applications. A king post extends vertically from a crossbeam to the apex of a triangular truss. The king post connects the apex of the truss with its base, holding up the tie beam at the base of the truss. Development of the king post structure terminates the central post before it reaches the apex of the roof truss. Instead, the king post is held in place by a collar beam, a secondary beam parallel to the tie beam. In this structure, the central post is termed the crown post.

The king post truss is used for simple roof trusses and short-span bridges. It is the simplest form of truss in that it is constructed of the fewest number of truss members. The truss consists of two rafters, one horizontal beam, serve as a ceiling joist.