truss

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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.

Truss

A composite structural system composed of straight members transmitting only axial tension or compression stresses along each member, joined to form a triangular arrangement.

arched truss

A truss with an arched upper chord and a straight bottom chord, with vertical hangers between the two chords.

bollman truss

A bridge truss with tension rods that radiate from the top of the two end posts to the bottom of the evenly spaced vertical chords; the roadbed is supported between the bottoms of two such trusses.

bowstring truss

A truss with one curved member in the shape of a bow and a straight or cambered member, which ties together the two ends of the bow.

curved truss

A truss, with either a flat howe or pratt configuration, but in a curved profile.

howe truss

A truss having upper and lower horizontal members, between which are vertical and diagonal members; the vertical web members take tension, and the diagonal web members are under compression.

king truss

A triangular truss with a single vertical king post that connects the apex of the triangle with the middle of the horizontal tie beam.

lattice truss

A truss consisting of upper and lower horizontal chords, connected by web members which cross each other, usually stiffened by joining at the intersection of the braces.

panel truss

A structural truss having rectangular divisions with diagonal braces between opposite corners.

pratt truss

A statically determinate truss, consisting of straight top and bottom chords, regularly spaced vertical compression members, and diagonal tension members; used for medium to long spans in buildings and for small bridges.

scissors truss

A type of truss used to support a pitched roof; the ties cross each other and are connected to the opposite rafters at an intermediate point along their length.

suspended arch truss

A truss with a straight upper chord and an arched lower chord, with vertical members between the two chords.

vierendeel truss

A steel open web truss composed of rectangular panels without diagonals, and with rigid joints between all the members.

warren truss

A truss having parallel upper and lower chords, with connecting members which are inclined, forming a series of approximately equilateral triangles.

Truss

 

a load-bearing structural system consisting of straight bars, the assembly joints of which are considered to be hinged for purposes of structural analysis of the design. Trusses are used primarily in construction—for the roofs of buildings, bridge spans, masts, supports for power transmission lines and gates in hydraulic engineering structures—and as load-bearing structural members in machines and mechanisms. They may be constructed from metal, reinforced concrete, wood, or combinations of materials, such as metal and wood. The material chosen and the design of the truss depend on the purpose of the building or structure, the type of roof, and method used to support the truss, and other factors.

Although they are considered to be hinged, the joints of trusses in practice have some degree of rigidity. In the design of trusses, provision is usually made for the application of external loads to the joints; for example, the stringers of a roof rest on a truss at the joints of the upper chord, and the beams of overhead cranes are secured to the joints of the lower chord of a truss. The assumptions of hinged connection of joints and the application of loads at the joints make it possible during the computation of stress to consider only the axial longitudinal forces in the bars; in this case, equally distributed stresses occur in the transverse sections of the bars, which makes it possible to make the most efficient use of the material. The forces in the bars of statically determinate, single-plane trusses are determined from the equations of statics; for three-dimensional trusses they are usually determined by converting the structure into a system of single-plane trusses. Statically indeterminate trusses are analyzed by means of the equations of the force method (seeSTRUCTURAL MECHANICS), in which the coefficients for the unknown quantities (displacements) are determined by considering only the effect of normal forces in elements of the truss. Live loads are computed from the tributary areas for loads.

L. V. KASAB’IAN

truss

[trəs]
(civil engineering)
A frame, generally of steel, timber, concrete, or a light alloy, built from members in tension and compression.

truss

truss
A structure composed of a combination of members (such as chords, 1, diagonals, and web members), usually in some triangular arrangement so as to constitute a rigid framework. See king-post truss, plated truss, queen-post truss, Vierendeel truss; also see bowstring beam.

truss

1. Med a device for holding a hernia in place, typically consisting of a pad held in position by a belt
2. Horticulture a cluster of flowers or fruit growing at the end of a single stalk
3. Nautical a metal fitting fixed to a yard at its centre for holding it to a mast while allowing movement
4. Architect another name for corbel
5. Chiefly Brit a bundle of hay or straw, esp one having a fixed weight of 36, 56, or 60 pounds