Final answer:
Trusses are the structural elements made of a series of triangles created to act as a major support beam in buildings, particularly noted for their use in rooftops of buildings like Gothic cathedrals.
Step-by-step explanation:
A series of triangles used to form an open web structural element to act as a beam is known as a truss. In construction, a truss is a rigid structure comprised of slender pieces joined together, creating a support system that covers sizable empty spaces or includes nonstructural panels. This structural element is widely utilized in various aspects of building and engineering, serving as a major support unit. Trusses are often used to support the roofs of buildings, such as in the iconic design of Gothic cathedrals where they are an integral part of the structure’s stability amidst the artistic architectural elements.
Other structural elements such as joists, rafters, and studs play their own unique roles within a building’s framework. For instance, joists are typically horizontal structural elements used to support a floor or ceiling, rafters form part of the roof framework, and studs are the vertical supports in wall construction. However, when it comes to forming an open web to serve as a major support beam, the truss is the correct answer.