Which type of truss has a curved upper member and a straight lower member?

The bowstring truss is characterized by its distinctive curved upper member and a straight lower member. This design allows the truss to efficiently distribute loads while also providing clear space underneath, making it popular for structures that require large open areas, such as gyms or auditoriums. The curved upper chord provides strength and rigidity, allowing for spans that can cover significant distances without the need for additional support columns.

In contrast, engineered trusses are typically custom-designed and can take various shapes but do not inherently feature a specific curved upper member. Lightweight trusses often refer to a design method utilizing materials intended to be lighter, though they may not have the bowstring shape. Open web trusses generally consist of straight members arranged in a web configuration, primarily focusing on providing structural support with minimal material but do not have the curved feature characteristic of bowstring designs. Therefore, the bowstring truss is uniquely identifiable by its combination of a curved top and straight bottom members.