A truss is made up of a web of triangles joined together to enable the even distribution of weight and the handling of changing tension and compression without bending or shearing. The triangle is geometrically stable when compared to a four (or more) -sided shape which requires that the corner joints are fixed to prevent shearing. Trusses consist of triangular units constructed with straight members. The ends of these members are connected at joints, known as nodes. They are able to carry significant loads, transferring them to supporting structures such as load-bearing beams, walls or the ground. In general, trusses are used to:

• Achieve long spans.
• Minimise the weight of a structure.
• Reduced deflection.
• Support heavy loads.

Trusses are typically made up of three basic elements:

• A top chord which is usually in compression.
• A bottom chord is usually in tension.
• Bracing between the top and bottom chords.

The top and bottom chords of the truss provide resistance to compression and tension and so resistance to overall bending, whilst the bracing resists shear forces. The efficiency of trusses means that they require less material to support loads compared with solid beams. Generally, the overall efficiency of a truss is optimised by using less material in the chords and more in the bracing elements.