KING POST:
King post truss is suitable for the span from 5m to 9m.this truss consist of two rafters, one tie beam, two struts, and a king post. The center king post is connected to the tie beam and ridge. The king post is the center vertical member. The inclined member connecting the base of the king post with the principal rafter at their center point is called struts. The strut prevents the principal king post extends vertically from a crossbeam (the tie beam) to the apex of a triangular truss.
The king post, itself in tension, connects the apex of the truss with its base, holding up the tie beam (also in tension) at the base of the truss. The post can be replaced with an iron rod called a king rod (or kingbolt) and thus a king rod truss. The king post truss is also called a "Latin truss." In traditional timber framing, a crown post looks similar to a king post,
but it is very different structurally: whereas the king post is in tension, usually supporting the tie beam as a truss, the crown post is supported by the tie beam and is in compression. The crown post rises to a crown plate immediately below and supporting collar beams; it does not rise to the apex like a king post. Historically a crown post was called a king post in England, but this usage is obsolete. Al rafter forms the bending.
QUEEN POST:
This truss type is used for spans greater than 9m to 14m. this truss differs from the king post truss in having two vertical members known as queen posts. this truss consists of two principal rafters, two queen posts. , the upper end of the queen post is kept in potion using a horizontal member known as a straining beam. one straining beam, two inclined struts, and a straining sill. A straining sill is introduced on the tie beam between the queen post to counteract the thrust of struts. The queen post has a single splay shoulder at the thrust of struts.
The trust from the two struts tends to force the feet of the queen post inwards, which is combinedly resisted by the tension joints between the tie beam and the queen post feet and the straining sill fixed between feet of the queen post. A queen post is a tension member in a truss that can span longer openings than a king post truss. A king post uses one central supporting post, whereas the queen post truss uses two. Even though it is a tension member rather than a compression member, they are commonly called a post. A queen post is often confused with a queen strut, one of two.
Compression members in roof framing do not form a truss in the engineering sense. Suitable joints should be made among various members of the queen post truss. A queen-post bridge has two uprights, placed about one-third of the way from each end of the truss. They are connected across the top by a beam and use a diagonal brace between the outer edges. The central square between the two verticals is either unbraced (on shorter spans),
or has one or two diagonal braces for rigidity. A single diagonal reaches between opposite corners; two diagonal braces may either reach from the bottom of each upright post to the center of the upper beam or form a corner-to-corner "X" inside the square.
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