machine structure
Structures which operate as machines or as integral parts of mechanized processes.
A machine structure is a fixed constructed object which functions as part of some mechanized process or which performs mechanized processes independently. The various types of machine structures may differ vastly from each other in appearance. These do not include structures built to shelter or enclose machinery; the machinery must be inextricably linked to the structure's form.
The physical form participates directly in the mechanical process. A surrounding building that only houses equipment has a separate sheltering role.
Appearance alone need not be shared across these structures. The relationship between the constructed object and its mechanical function is the common feature.