The theory of designing rational load-bearing structures from the standpoint of strength, durability, manufacturability, and material consumption has too much of an energy basis. New variational principles operate at all levels of designing the configuration of load-bearing structures: topology, geometry, parameters of elements with parallel selection of materials. They can also be used for rational distribution of load on the structure. The study examined the foundations of new variational principles of synthesis of supporting structures with the content of an objective criterion of optimality of their practical application. Based on this, a rational energy principle was selected in the design of supporting structures, as well as algorithms for the development of rational systems focused on software design. The obtained dependencies as a result of the study allow to obtain a rational solution in strength, durability, manufacturability, and material consumption, which in turn helps to reduce the cost of construction of buildings and structures, as well as the costs of their reconstruction. Also, the proposed algorithms for the development of rational systems are aimed at software design.