OPTIMAL HEIGHT OF STEEL I-BEAMS WITH CHANGING THE WIDTH OF THE FLANGES

The article improves the methodological approach to finding the best constructive solution for a beam made of welded steel I-beams with a variable flange width. An idealized physicalmathematical model of the construction of a beam made of welded steel I-beams with a tapered flange depending on the consumption of steel and changes in the geometric characteristics of the cross-section is described. The bending strength conditions of the beam are taken as limitations. The purpose of the research was to develop an approach to establish the regularity of a rational constructive solution depending on the variability of the width of the flanges of the elastic steel I-beam along its length.It is shown that determining the pattern of changes in the stress-strain state of steel beams with variable shelf width at a constant cross-section height is an urgent task. As a result on the optimal consumption of steel for the structure is shown. A pattern hasbeen established between the variable parameter of the width of the flanges and the coordinate of the calculated section. The effect of displacement of the calculated section of the beams in the direction of a decrease in the geometric characteristics of thebeams, depending on the degree of variability of the width of the shelf along the length of the beam, has been confirmed. Thus, in beams with a variable shelf width at a constant wall height, the maximum stresses occur in the cross-section that does not havethe maximum geometric characteristics.Analytical dependences of determining the optimal height depending on the variability of the width of the flanges were obtained. The methodology of research in the search for a rationalconstructive solution is described. It is shown that in the case of the variability of the width of the flanges, the parameter of the optimal height of the beam depends on the load distribution unction along the length of the beam.A cantilever-clamped elastic beam of I-beam cross-section was studied. Through the relative parameter of the variability of geometric characteristics, it is shown that when the parameterof the variability of the shelf width is changed, the calculated cross-section moves toward the free end with smaller geometric characteristics.Corresponding numerical studies have been carried out, which are illustrated by graphs. The conducted research allows choosing theoptimal dimensions of a steel welded I-beam by changing the width of the flanges that perceive bending moments. According to the research results, the degree of variability of the cross-sectionis recommended for rational designs of steel Ibeams by changing the width of the flanges.