Structural Form #4 – Trusses
A truss is an assembly of beams or other elements that creates a rigid structure. In engineering, a truss is a structure that “consists of two-force members only, where the members are organized so that the assemblage as a whole behaves as a single object”. A “two-force member” is a structural component where force is applied to only two points. Although this rigorous definition allows the members to have any shape connected in any stable configuration, trusses typically comprise five or more triangular units constructed with straight members whose ends are connected at joints referred to as nodes.
A truss can be thought of as a particular type of beam, where all the inner workings of the beam are exposed. Trusses divert a load, in the same way that beams do, thus creating an open space beneath them. The truss curves like a beam (with the top in compression and the bottom in tension for the example below).
The unique thing about a truss is that while the truss as a whole curves, each individual member carries its load by tension or compression. Therefore, individual members get shorter or longer (with no curving), but this causes the truss as a whole to curve.