Space frames are typically designed using a rigidity matrix. The special characteristic of the stiffness matrix in an architectural space frame is the independence of the angular factors. If the joints are sufficiently rigid, the angular deflections can be neglected, simplifying the calculations. The simplest form of the space frame is a horizontal slab of interlocking square pyramids and tetrahedra built from aluminum or tubular steel struts. In many ways, this looks like the horizontal jib of a tower crane repeated many times to make it wider. A stronger form is composed of interlocking tetrahedra in which all the struts have unit length. More technically this is referred to as an isotropic vector matrix or in a single unit width an octet truss. More complex variations change the lengths of the struts to curve the overall structure or may incorporate other geometrical shapes. Space frames are a common feature in modern building construction; they are often found in large roof spans in modernist commercial and industrial buildings.
Advantages of Spaceframe Structures
- One of the most important advantages of a space frame structure is its lightweight. It is mainly because material is distributed spatially in such a way that the load transfer mechanism is primarily axial-tension or compression. Consequently, all material in any given element is utilized to its full extent.The units of space frames are usually mass-produced in the factory so that they can take full advantage of an industrialized system of construction. Space frames can be built from simple prefabricated units, which are often of standard size and shape. Such units can be easily transported and rapidly assembled on-site by semi-skilled labor. Consequently, space frames can be built at a lower cost.
- A space frame is usually sufficiently stiff in spite of its lightness. This is due to its three-dimensional character and to the full participation of its constituent elements. Engineers appreciate the inherent rigidity and great stiffness of space frames and their exceptional ability to resist the unsymmetrical or heavy concentrated load. Possessing greater rigidity, the space frames also allow greater flexibility in the layout and positioning of columns.
- Space frames possess a versatility of shape and form and can utilize a standard module to generate various flat space grids, latticed shell, or even free-form shapes. Architects appreciate the visual beauty and the impressive simplicity of lines in space frames. A trend is very noticeable in which the structural members are left exposed as a part of the architectural expression. The desire for openness for both visual impact as well as the ability to accommodate variable space requirements always calls for space frames as the most favorable solution.