Election of rational height of steel beam structures taking into account the dynamics coefficient during episodic loading

The article develops a generalized approach to finding the rational height of a steel beam structure: a truss or a roof beam under the action of an episodic short-term pulse load. The research was carried out based on creating a generalized physical and mathematical model for finding the rational height of a steel truss of increased reliability, taking into account the action of a pulsed concentrated load acting in the middle of the span of the structure. The choice of the rational height of a steeltruss was made according to the generalized optimal design method, taking into account the constraints on strength and stability. Therefore, it can be assumed that the applied methodological approach gives a limited-optimal result given the complexity of the problem, but it is sufficient for variant design. The analytical expression of steel consumption was taken as the objective function, taking into account the dynamic coefficient for bending moment. The analytical objective function of steel consumption for a truss structure was written taking into account the unification of steel elements, and the influence of design coefficients was also taken into account. The physical and mathematical model ofthe steel truss is the design of an ideal I-beam taking into account the shear deformation of the section when determining the dynamic coefficient. Analytical expressions (rationality criteria) are obtained for determining the rational (bounded-optimal) height of the truss taking into account the influence of the dynamic coefficient. Numerical studies of the bounded-optimal height of the steel roof truss structure are carried out. It is confirmed that depending on the static and impulse load and the geometric parameters of the steel roof structure, the dynamic coefficient affects the determination of the rational height of the steel structure. The obtained criterion of the rationality of the structure also takes into account the influence of the ratio of the selfweight of the steel truss structure and the structure taking into account the enclosing load-bearing structures of the roof slabs. The analytical criterion of the rational height of the steel truss with the influence of the impulse loadalso includes the criterion of the rationality of the optimal height of the truss under static load. According to the research results, a practical method for determining the rational design of a steel roof truss has been obtained during variant design taking into account the action of impulse loads.