What structural system consists of vertical and horizontal members that function as a single unit due to rigid connections?

The structural system that consists of vertical and horizontal members functioning as a single unit due to rigid connections is known as a rigid frame. In this type of frame, the connections between beams and columns are designed to be rigid, allowing them to resist bending moments and shear forces. This rigidity contributes significantly to the overall lateral stability of the structure, making it well-suited for both gravity and lateral loads, such as wind or seismic forces.

Rigid frames are commonly used in buildings and various structures because they can support large spans and are efficient in terms of material usage. The interconnected nature of the vertical and horizontal elements allows for a continuous load path, improving the structure's response to dynamic loads.

In contrast, other frame systems like composite, flexible, or dynamic frames do not possess the same rigid joint connections, resulting in different structural behavior under load. For instance, flexible frames allow for rotational movement at the joints, while composite frames utilize various materials but do not necessarily indicate rigid connections. Dynamic frames might refer to systems designed to respond to dynamic loads but lack the consistent rigidity found in rigid frames.