The object – Combined steel rod bearing structures of coatings and ceilings, which work on static load; the goal – to solve an important scientific and technical problem in the development of theoretical bases of calculation and design of rational (with reduced steel costs and labor intensity of manufacturing) of combined steel structures of coatings and overlays, as well as improvement of their constructive forms; methods - methods of structural mechanics and theory of reliability of steel structures; methods of selecting rational constructive forms; standard test methods for steel structures; Novelty - for the first time, a generalized calculation model of combined steel structures in the form of an indistinguishable beam (reflecting the beam of stiffness 3) on the intermediate elastic supports (which reflect the reinforcement of the beam) is proposed for the first time, and the interaction of the components of which can increase the efficiency of structures, including by reducing them height; formulated new theoretical foundations and created a general calculation method for regulating the SDS of combined steel structures on the basis of the energy-law principles (in particular, the Lagrange principle) and taking into account the deformed state of the beam of stiffness, which allows not only to determine the rational topology and rigid characteristics of the cross sections of structural elements, but also to regulate the distribution of effort in the beam of stiffness in such a way that their limit values are achieved simultaneously not in one, but in many cross-sections , that is, they received a rational design; New scientific theoretical bases of the unified algorithm of the calculation regulation of the SDS and rational design of the combined steel structures with the given parameters of bearing capacity and reliability are developed; The results of theoretical studies of combined structures in the process of regulating their SDS at arbitrary loads, influences, and boundary conditions have been obtained, which allowed not only to determine the principles and factors of their formation and rational values of geometric parameters, but also to formulate a new criterion for the rationality of combined steel structures; new laws of the SDS of combined steel structures were established at the choice of rational parameters, which makes it possible to form a new subclass of combined structures. New regularities of creation of a smooth-stressed state in calculated sections according to the results of experimental research of rational combined steel structures (small-element shpengel and metal-walled farms), which were calculated and designed by the developed method with the calculation of their SDS; New scientific provisions have been developed and improved: methods of designing combined steel structures (based on the results of theoretical and experimental research) and the principles of their use instead of typical designs, as well as the extended area of rational application; constructive solutions of combined steel structures on the basis of established new scientific principles and factors of their design, calculation, search of effective rational values of geometric parameters; Further development: analytical and experimental approach to the method of calculating combined steel structures as statically determined systems, which allowed to significantly simplify the calculation dependencies and reduce the calculation method to simple and easy to use solutions; a complex of new scientifically-based methods made it possible to create programs of calculation, regulation of SDS and rational design of combined steel structures of coatings and overlaps of buildings and structures, hanging and cable systems, etc., as structural elements of which beams, rods and cables were applied; results - developed theoretical bases of calculation and design of rational (with reduced steel costs and labor productivity of manufacturing) combined steel structures of coatings and overlays, as well as their constructive forms have been improved. New scientific and practical results are obtained and the theory of rational design of combined steel constructions is developed, which allows to systematically increase their efficiency and efficiency. The results of the research have revealed the wide possibilities of purposeful design of rational combined steel structures, give the opportunity to make comprehensive decisions that will provide better design, implementation of competitive solutions and expansion of their use, which will restore the massive use of such effective structures and provide a general economic effect. The disclosure of the potential for SDS regulation by the calculation method in the combined systems has created the basis for the development of scientific foundations for obtaining new generation designs. industry - construction.
