A bent is a framework composed of several structural members that defines the cross-section of a timber frame

Timber framing

Timber framing , or half-timbering, also called in North America "post-and-beam" construction, is the method of creating structures using heavy squared off and carefully fitted and joined timbers with joints secured by large wooden pegs . It is commonplace in large barns...

 building or supports a trestle

Trestle

A trestle is a rigid frame used as a support, especially referring to a bridge composed of a number of short spans supported by such frames. In the context of trestle bridges, each supporting frame is generally referred to as a bent...

. The term bent is probably an archaic past tense of the verb to bind, referring to the way the timbers of a bent are joined together. Compare this with the term bend for a class of knots.

Bents are the building blocks which define the overall shape and character of a structure. They do not have any sort of pre-defined configuration in the way that a Pratt truss does. Rather, bents are simply cross-sectional templates of structural members (i.e. rafters, joists, posts, pilings, etc.) which repeat on parallel planes along the length of the structure. The term bent is not restricted to any particular material. Bents may be formed of wooden piles, timber framing, steel framing, or even concrete.

Construction

Bents are generally pre-assembled, either at the timber framing company's shop or at the construction site. After the basic post and beam structure of the frame has been set in place, the bents are then lifted and simply dropped into place one by one by the crane. Next, the workers bring in additional members, purlin

Purlin

In architecture or structural engineering or building, a purlin is a horizontal structural member in a roof. Purlins support the loads from the roof deck or sheathing and are supported by the principal rafters and/or the building walls, steel beams etc...

s, which tie them together and give the frame a more rigid structure. This process is very safe and efficient as it allows a crew to assemble a large portion of the frame without ever stepping off the ground. This in turn, minimizes the amount of time that the crew must spend several stories in the air clambering along beams not much wider than their own feet.

External links

• Glossary Useful terms in the timber framing trade.
• Blog Entry Some good pictures and a short narrative about raising bents.