A three dimensional (3D) truss is a type of framework used to give extra strength and support to structures such as bridges and buildings. Sometimes called a space truss, it is made up of triangles that are arranged into three dimensional triangular shapes such as tetrahedrons. These trusses are extremely strong and are able to withstand a great deal of force without changing shape or breaking.
Like other trusses, the 3D truss is made up of a series of triangular shapes. By using triangular pieces, trusses are able to withstand a great deal more force than structures made of other shapes. Triangular shapes are used in trusses because they will not lose their shape when subjected to stress. Given enough force, a truss can break apart, but the triangular sections are not subject to angular changes the way that other shapes, such as quadrilaterals, are.
The most commonly used shape in a 3D truss is a tetrahedron. This three dimensional shape is made up of four triangles, arranged so that one triangle forms the shape's base and the other three attach to each edge of the base, meeting in a point at the top. A similar structure, a pyramid, which has a square base and four triangular sides that meet at a point, can also be used.
Trusses can be made out of a variety of materials. Wooden trusses are common in the construction of houses or other small structures. Large buildings or structures that undergo a great deal of stress, such as bridges will often make use of metal 3D trusses.
The 3D truss is commonly used to support a number of different structures. Floors, platforms, and roofs make use of these trusses because they remain strong and stable in the middle as well as on the edges of the structure. For very large platform-like structures, additional support beams may be placed under the center of the 3D truss to make the structure even stronger. Towers, especially electrical towers, can be made up of a 3D truss, reaching to great heights without collapsing.
Many structures used in space projects are built as a series of 3D trusses. This shape is easier to construct than honey-comb shaped supports and can maintain its rigid shape in a variety of different conditions. Arranging a series of tetrahedrons together in different ways can create structures in any 3 dimensional shape, with flat or contoured edges.