Truss

A truss is an assembly of straight structural members, typically five or more, arranged in triangular units and connected at joints called nodes to form a rigid structure. Architectural and engineering trusses are built from two force members, meaning each member carries load applied only at its two end joints, so the members work purely in tension or compression rather than bending. In a typical truss the top members, called top chords, are usually in compression, the bottom members, the bottom chords, are usually in tension, and the interior members connecting them are called webs. A truss confined to one plane is a planar truss, while one whose members extend into three dimensions is a space frame. The word truss comes from the Old French trousse, meaning a collection of things bound together, current from around 1200 AD. The Pratt truss, patented in 1844 by the Boston railway engineers Caleb Pratt and his son Thomas Willis Pratt, arranges vertical members in compression and diagonal members in tension and remained a popular bridge design as builders shifted from timber to iron and steel. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/