In this article on increasing the efficiency of steel combined structures, the tasks of rational design, regulation and control of structural parameters of elements, the use of steels with increased mechanical properties are considered. It is shown that for a six-span stiffening girder of a combined truss with elastic supports, which operates under a distributed load, the moment is 72 times smaller than the moment of a single-span beam. It is suggested to use high-strength steel for truss braces. Rationality criteria are proposed.
In this article, the rational constructive form of the combined steel truss with a span of 30 meters is received, with 59% fewer elements than the typical. Calculated regulation methods are offered stress-deformation state (SDS) combined steel trusses, which make it possible to increase their efficiency. Methods of estimated SDS regulation in combined steel trusses are given: change in the stiffness of the rodsand the creation of eccentricities in the nodes connecting the lattice to the upper belt and supporting eccentricities.