What is the structure characterized by parallel top and bottom chords?

A structure characterized by parallel top and bottom chords is known as a flat truss. This type of truss comprises two horizontal members (chords) that run parallel to one another, which provides stability and allows for even load distribution across the truss. Flat trusses are commonly used in applications where a level surface is needed, such as in roof supports for flat roofs or in bridges.

In contrast, a scissor truss features a design in which the top chords meet at a central point while the bottom chords remain parallel, creating a shape that resembles scissors. A pitched roof typically involves sloped surfaces, where rafters or trusses are angled to create a peak, which is distinct from the parallel chord design of the flat truss. A gabled structure refers to a building that has a triangular section at one or both ends of the roof, which also does not align with the configuration of a flat truss.