Methodology for Determining the Natural Circular Vibrations of Steel Roof Trusses by the Calculation Scheme of the Ideal I-Beam Ability of Steel Elements of Steel Trusses

A methodology has been developed for conducting generalized studies of natural circular vibrations of steel roof structures by beam analogy during impulsive loading. It is proposed that the natural circular frequency of vibrations of rod elastic structures of roof trusses be estimated through the coefficient of reducing the bending stiffness of the steel roof truss to the stiffness of an ideal I-beam. Numerical studies of the natural circular frequencies of vibrations of steel roof trusses with a span of 12.0 m and 15.0 m under the action of a uniformly distributed and concentrated load have been carried out. Accordingly, the coefficient of reducing the stiffness of the steel roof truss to the stiffness of an ideal I-beam has been determined. It is shown that at the same cross-sectional height, the bending stiffness of steel roof trusses is less than the bending stiffness of an ideal I-beam due to the influence of shear deformation of the cross-section of the core structure. Numerical studies have been carried out and the impact of the truss support conditions on the natural circular frequencies of oscillations has been established. It has been shown that the natural frequency of oscillations of beam structures with pin supports is greater than with traditional support when one support is pin support and the other is roller fixed. The results of the studies are used during variant design to select a rational constructive solution for metal lattice structures.