What is a framed structure consisting of a triangle or group of triangles arranged in a single plane called?

A framed structure that consists of a triangle or a group of triangles arranged in a single plane is referred to as trusses. Trusses are designed to support loads over a span using their triangular configuration, which efficiently distributes weight. The triangular shapes create a stable structure, allowing for greater strength while using less material than solid beams. This makes trusses an ideal choice in many construction applications, including roofs and bridges.

In contrast, piers are vertical structures that provide support beneath beams or bridges but do not have the triangular configuration characteristic of trusses. A girder is a large beam that supports smaller beams or trusses, while a grillage refers to a framework of beams that distributes loads more broadly, also differing from the triangular arrangement of trusses. The unique design of trusses allows them to handle tension and compression efficiently, which is a key reason for their widespread use in construction.