In structural engineering, a Warren truss or equilateral truss [1] is a type of truss employing a weight-saving design based upon equilateral triangles. It is named after the British engineer James Warren, who patented it in 1848.
It was patented in 1848 by its designers James Warren and Willoughby Theobald Monzani.[ citation needed ]
The Warren truss consists of longitudinal members joined only by angled cross-members, forming alternately inverted equilateral triangle-shaped spaces along its length. This gives a pure truss: each individual strut, beam, or tie is only subject to tension or compression forces, there are no bending or torsional forces on them.
Loads on the diagonals alternate between compression and tension (approaching the centre), with no vertical elements, while elements near the centre must support both tension and compression in response to live loads. This configuration combines strength with economy of materials and can therefore be relatively light. The girders being of equal length, it is ideal for use in prefabricated modular bridges.
It is an improvement over the Neville truss in which the elements form isosceles triangles. [2]
A variant of the Warren truss has additional vertical members within the triangles. [1] These are used when the lengths of the upper horizontal members would otherwise become so long as to present a risk of buckling [i] These verticals do not carry a large proportion of the truss loads; they act mostly to stabilise the horizontal members against breaking down.
The Warren truss is a prominent structural feature in hundreds of hastily constructed aircraft hangars in WW2. In the early parts of the war, the British and Canadian government formed an agreement known as the British Commonwealth Air Training Plan which used newly constructed airbases in Canada to train aircrew needed to sustain emerging air forces. Hundreds of airfields, aprons, taxiways and ground installations were constructed all across Canada. Two characteristic features were a triangle runway layout and hangars built from virgin British Columbia timbers with Warren truss configuration roofs. [5] [6] Many still remain in service.
Warren truss construction has also been used in airframe design and construction, for substantial numbers of aircraft designs.
An early use was for the interplane wing struts on some biplanes. The Italian World War I Ansaldo SVA series of fast reconnaissance biplanes were among the fastest aircraft of their era, while the Handley Page H.P.42 was a successful airliner of the late 1920s and the Fiat CR.42 Falco Falco fighter remained in service until World War II.
The Warren truss is also sometimes used for fuselage frames, such as in the Piper J-3 Cub and Hawker Hurricane.
Structural engineering is a sub-discipline of civil engineering in which structural engineers are trained to design the 'bones and joints' that create the form and shape of human-made structures. Structural engineers also must understand and calculate the stability, strength, rigidity and earthquake-susceptibility of built structures for buildings and nonbuilding structures. The structural designs are integrated with those of other designers such as architects and building services engineer and often supervise the construction of projects by contractors on site. They can also be involved in the design of machinery, medical equipment, and vehicles where structural integrity affects functioning and safety. See glossary of structural engineering.
A truss is an assembly of members such as beams, connected by nodes, that creates a rigid structure.
In architecture and structural engineering, a space frame or space structure is a rigid, lightweight, truss-like structure constructed from interlocking struts in a geometric pattern. Space frames can be used to span large areas with few interior supports. Like the truss, a space frame is strong because of the inherent rigidity of the triangle; flexing loads are transmitted as tension and compression loads along the length of each strut.
A beam is a structural element that primarily resists loads applied laterally across the beam's axis. Its mode of deflection is primarily by bending, as loads produce reaction forces at the beam's support points and internal bending moments, shear, stresses, strains, and deflections. Beams are characterized by their manner of support, profile, equilibrium conditions, length, and material.
A cantilever bridge is a bridge built using structures that project horizontally into space, supported on only one end. For small footbridges, the cantilevers may be simple beams; however, large cantilever bridges designed to handle road or rail traffic use trusses built from structural steel, or box girders built from prestressed concrete.
A truss bridge is a bridge whose load-bearing superstructure is composed of a truss, a structure of connected elements, usually forming triangular units. The connected elements, typically straight, may be stressed from tension, compression, or sometimes both in response to dynamic loads. There are several types of truss bridges, including some with simple designs that were among the first bridges designed in the 19th and early 20th centuries. A truss bridge is economical to construct primarily because it uses materials efficiently.
A self-anchored suspension bridge is a suspension bridge type in which the main cables attach to the ends of the deck, rather than directly to the ground or via large anchorages. The design is well-suited for construction atop elevated piers, or in areas of unstable soils where anchorages would be difficult to construct.
A girder is a beam used in construction. It is the main horizontal support of a structure which supports smaller beams. Girders often have an I-beam cross section composed of two load-bearing flanges separated by a stabilizing web, but may also have a box shape, Z shape, or other forms. Girders are commonly used to build bridges.
The term structural system or structural frame in structural engineering refers to the load-resisting sub-system of a building or object. The structural system transfers loads through interconnected elements or members.
A tied-arch bridge is an arch bridge in which the outward-directed horizontal forces of the arch(es) are borne as tension by a chord tying the arch ends rather than by the ground or the bridge foundations. This strengthened chord may be the deck structure itself or consist of separate, independent tie-rods.
In mechanical engineering, stressed skin is a rigid construction in which the skin or covering takes a portion of the structural load, intermediate between monocoque, in which the skin assumes all or most of the load, and a rigid frame, which has a non-loaded covering. Typically, the main frame has a rectangular structure and is triangulated by the covering; a stressed skin structure has localized compression-taking elements and distributed tension-taking elements (skin).
A steel building is a metal structure fabricated with steel for the internal support and for exterior cladding, as opposed to steel framed buildings which generally use other materials for floors, walls, and external envelope. Steel buildings are used for a variety of purposes including storage, work spaces and living accommodation. They are classified into specific types depending on how they are used.
A Howe truss is a truss bridge consisting of chords, verticals, and diagonals whose vertical members are in tension and whose diagonal members are in compression. The Howe truss was invented by William Howe in 1840, and was widely used as a bridge in the mid to late 1800s.
A Brown truss is a type of bridge truss, used in covered bridges. It is noted for its economical use of materials and is named after the inventor, Josiah Brown Jr., of Buffalo, New York, who patented it July 7, 1857, as US patent 17,722.
Compression members are structural elements that are pushed together or carry a load; more technically, they are subjected only to axial compressive forces. That is, the loads are applied on the longitudinal axis through the centroid of the member cross section, and the load over the cross-sectional area gives the stress on the compressed member.
A king post is a central vertical post used in architectural or bridge designs, working in tension to support a beam below from a truss apex above.
James Warren (1806–1908) was a British engineer who, around 1848 to 1907, patented the Warren-style truss bridge and girder design. This bridge design is mainly constructed by equilateral triangles which can carry both tension and compression. The first suspension bridge to utilise a Warren truss in its design was the Manhattan Bridge in New York City.
In structural engineering, a diaphragm is a structural element that transmits lateral loads to the vertical resisting elements of a structure. Diaphragms are typically horizontal but can be sloped in a gable roof on a wood structure or concrete ramp in a parking garage. The diaphragm forces tend to be transferred to the vertical resisting elements primarily through in-plane shear stress. The most common lateral loads to be resisted are those resulting from wind and earthquake actions, but other lateral loads such as lateral earth pressure or hydrostatic pressure can also be resisted by diaphragm action.
The Prince Alfred Bridge is a wrought iron truss and timber beam partially-disused road bridge over the Murrumbidgee River and its floodplain at Middleton Drive, Gundagai, Cootamundra-Gundagai Regional Council, New South Wales, Australia. The heritage-listed road bridge was designed by William Christopher Bennett and built from 1864 to 1867 by Francis Bell. It is also known as Prince Alfred Bridge – Iron Road Bridge and Iron Bridge over Murrumbidgee River at Gundagai. The iron bridge is owned by Transport for NSW and the timber viaduct is owned by Crown Lands. The bridge was added to the New South Wales State Heritage Register on 5 July 2019 and on the Register of the National Estate on 21 March 1978.
In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of struts, which act in compression or tension as the need arises, and/or wires, which act only in tension.