AbstractControl of structures against environmental loads, such as earthquakes and wind, is generally conceived as the protection of a system with no interaction with the surrounding buildings.When a large facility is considered, subsystems within it are identified and, in case, controlled. Attention is focused throughout this paper on the interaction of these subsytems in extreme conditions. The new concept of controlling the failure mode arises.The paper discusses the motivations leading one to adopt such an approach and the guidelines for its design.