What is the term used for the part of a building that is located below grade and serves as a platform that supports the weight of the building?

The term utilized to describe the section of a building that is situated below grade and functions as a platform to bear the weight of the entire structure is "substructure." This term encompasses the components of a building that are located underground, including the foundation, which is crucial for providing stability and support.

The substructure is essential because it transfers loads from the superstructure, which is the part of the building above ground, to the soil. Proper design and construction of the substructure ensure that the building can withstand various forces, such as those from wind, snow, and seismic activity.

In contrast, the main structure refers to the primary components that bear loads above ground; the framework specifically relates to the skeletal system that supports the overall structure but is not exclusive to below-grade elements; and the superstructure refers to everything above the foundation, including walls, roofs, and floors. Understanding these distinctions is important for those involved in structural engineering and real estate.