The article examines the question of the effectiveness of rational steel combined trusses compared to: typical, optimized, with adaptive regulators and rational ones with regulation of the stress-strain state. A comparative analysis of their technical and economic indicators by material intensity was carried out. The mass efficiency of a rational combined steel truss compared to a typical truss reaches 16%, an optimized truss, also compared to a typical truss, is 14%, and a truss with adaptive regulators is 17%. It is shown that the rational design of the truss, without the use of complex analytical or numerical optimization processes, allows to achieve the same parameters. The results of numerical studies have shown that rational design is the most effective method of increasing the efficiency of trusses. Adjusting the stress-strain state of the truss by arranging support eccentricities equal to half the height of the truss makes it possible to reduce the maximum moment in the stiffening girder above the second support by 18%, which will further increase its efficiency.