1. Rigid structural framework of timbers bridging a space, each end resting on supports at regular intervals (often defining bays), to provide support for the longitudinal timbers (e.g. purlins) that carry the common rafters and the roof-covering. Its stability, dependent on e.g. triangulation, also prevents the roof from spreading. Types of truss or roof-structure include:aisle: in timber-framed work a complete aisled structure set over the tie-beams;Belfast or bowstring: of timber, for spans of up to 15 metres, with a segmental top member joined to a horizontal lower chord, string, or tie (sometimes slightly cambered) by inclined lattice-members;box-framed: complete cross-frame the entire height of the building in a box-framed structure;closed: with the spaces between its members filled in (e.g. between rooms or at gable-ends);common rafter: type of roof constructed of pairs of common rafters. If common rafters are held together with collars or tie-beams, the resulting structure is called a coupled rafter roof or a trussed rafter roof, to emphasize the presence of additional components;compass or compass-headed roof: one in which the braces, rafters, and collar-beams of each truss are arranged and shaped in the form of an arch, thus creating a half-cylindrical underside to the roof-structure; coupled rafter roof: a common rafter roof, but with the rafters connected by collars; cradle: where the tie from the foot of one rafter is attached to the opposite rafter at a considerable height from its foot, or the structure has collar-beams and braces as well, thus forming a shape like part of a polygon which, if upside-down, could resemble a cradle, the result is called a cradle-roof; cruck: pair of cruck blades with transverse members (e.g. tie-beam, collar, saddle, yoke, or spur);cut: truncated, with the part of a truss over the collar-beams flattened off;double arch-braced: with two pairs of arch-braces forming a continuous curve from where the braces are supported to where they join in the middle of the collar;double-framed roof: with principals or principal rafters supporting horizontal members (e.g. purlins) which carry the common rafters: the principal rafters divide the length of the roof into bays; double hammer-beam: as a hammer-beam truss, but with upper hammer-beams carrying upper hammer-posts (e.g. Church of Sts Peter & Paul, Knapton, Norfolk);false hammer-beam: with a transverse timber like a hammer-beam, but braced to a principal or collar without a hammer-post;hammer-beam: with transverse timbers, like a tie-beam from which the middle section has been removed, supported on braces and carrying hammer-posts and braces that carry the open structure of the roof;intermediate or secondary: truss of relatively light construction between the main trusses (defining the bays) and carried on horizontal plates spanning between the main trusses rather than on a main structure rising from the ground;kerb-principal: with two curved kerb-principals rising from a tie-beam to a collar on either side of a crown strut;king-post: with an upright post set on a tie-beam or collar rising to the apex to support a ridge-piece;open: with spaces between timbers unfilled (e.g. in a hall of two bays when one truss supports the structure half-way along its length, the trusses at the ends of the hall being closed);post-and-rafter: with principal rafters and wall-posts strengthened by knee- or sling-braces, but no tie-beams;principal rafter roof: type of structure in which common rafters are supported on plates and purlins, the latter carried on principal rafters forming part of a truss;queen-post: with paired vertical posts set on the tie-beam and supporting plates or purlins;scissor-truss: with braces crossing and fixed to each other, thus tying pairs of rafters together;single-framed roof: constructed with no main trusses, the rafters being fixed to a wall-plate and ridge, or with horizontal members entirely omitted, so the roof consists only of common rafters butting together at the apex of the roof;spere: set at the lower end of a hall dividing the cross-entry or screens passage from the hall itself.
2. Element projecting from the naked of a wall, e.g. a console, corbel, modillion, etc.
Alcock,, Barley,, Dixon,, & and Meeson (1996);
W. McKay (1957);
W. Papworth (1892);
Sturgis et al. (1901–2)
truss / trəs/ • n. 1. a framework, typically consisting of rafters, posts, and struts, supporting a roof, bridge, or other structure: roof trusses. ∎ a surgical appliance worn to support a hernia, typically a padded belt. ∎ a large projection of stone or timber, typically one supporting a cornice. 2. a compact cluster of flowers or fruit growing on one stalk. 3. Sailing a heavy metal ring securing a lower yard to its mast. • v. [tr.] 1. tie up the wings and legs of (a chicken or other bird) before cooking. ∎ tie up (someone) with their arms at their sides: I found him trussed up in his closet. 2. [usu. as adj.] (trussed) support (a roof, bridge, or other structure) with a truss or trusses. DERIVATIVES: truss·er n.
truss, in architecture and engineering, a supporting structure or framework composed of beams, girders, or rods commonly of steel or wood lying in a single plane. A truss usually takes the form of a triangle or combination of triangles, since this design ensures the greatest rigidity. Trusses are used for large spans and heavy loads, especially in bridges and roofs. Their open construction is lighter than, yet just as strong as, a beam with a solid web between upper and lower lines. The members are known as tie-beams, posts, rafters, and struts; the distance over which the truss extends is called the span. The upper and lower lines or beams are connected by web members.
a pack or package; a bundle of hay or straw; a cluster of flowers or fruit.
Examples : truss of minor associations, 1878; of the most barbarous authors, 1531; of grass, 1400; of hay, 1483; of straw, 1609; of trifles.