Review article

The article proposes an analytical-numerical method for calculating the rod elements of lightweight steel structures for general stability, in which the reduced section is replaced with the unreduced one with compensating loading with a fictitious longitudinal force. The dependence of this force with uniaxial or biaxial eccentricities on the acting longitudinal force is established when they are combined acting on fictitious stresses in the center of the weakening gravity of the rod most stressed section. Therewith, the effect of displacements corresponding to the stability tasks (bending, bending-torsional or spatial ones) is taken into consideration. The analytical part of the stability problems` solution is constructed for the known parameters of the real abatement of the cross section, which is determined numerically under the combined action of all efforts using the EN 1993-1-3-2004 in combination with the "Cross-section" algorithm. To reduce the volume of calculations, there is proposed a reverse course of solving the stability problem in dimensionless parameters. The section reduction and the actual forces are numerically determined according to the limiting state of the rod in the most loaded initial section at given force parameters (relative eccentricities of the longitudinal force, taking into account displacements). Then, depending on the flexibility of the rod, the corresponding loading of the rod on its supports is specified by the reverse analytical solution.