trusses

A truss is a structural framework composed of straight members connected at their ends to form a system of triangles. The triangular geometry distributes loads so that members carry mainly axial forces—tension or compression—while minimizing bending. This allows efficient transfer of loads to supports and enables long spans with relatively light members.

Trusses are commonly categorized as plane (two-dimensional) or space (three-dimensional). Plane trusses are built from members arranged in a single plane and include configurations such as King post, Queen post, Pratt, Howe, and Warren. Space trusses and space frames use three-dimensional networks of members, often connected to form rigid, lightweight lattices suitable for roofs, towers, and sports arenas.

Key components of a truss are its members and joints (nodes). In many analyses, joints are assumed pin-connected and members are two-force elements, carrying only axial tension or compression. This simplifies calculation using the method of joints or the method of sections, though modern practice may employ numerical methods for complex or redundant systems.

Design and analysis considerations include material choice (steel, timber, aluminum), member cross-sections, connection details, and resistance to buckling, fatigue, and corrosion. Trusses excel at distributing concentrated loads to supports and can span long distances with economic material use. They are less suited to carrying distributed loads directly and require precise fabrication and stiff joints to maintain performance under service conditions.

Historically, trusses became prominent in bridge and roof construction during the 19th century and remain fundamental to modern structural engineering, from large bridges to stadium roofs and aircraft or aerospace lattice structures.