Numerical Study of the Effect of the Wall Thickness of a Steel I-Beam on the Form of Loss of Local Stability

Abstract

A large number of elements of steel building structures made of I-beam section profiles. It is economically advantageous to use I-beams with thin web thickness (vertical member of I-beam section). The safe use of thin web thickness of I-beams prevents possible deformation of the section profile member of the steel I-beam under load, before the loss strength (resistance) of the element. Research on the loss of stability. i.e. buckling of web plate (vertical member of I-beam) shows that thin web plate thickness does not reduce safety of the building and structures during its operation and maintenance. The results of calculation on stability of test models of I-section steel beams with a span of 12 m with various web thicknesses: 4, 5, 6, 7, 8, 9 and 10 mm. The load is collected for beams with steps of 6 m. The calculations are performed in a program “the SCAD Office computer complex”, which is based on the finite element method. The design testing model which is a simple supported beam is prepared in a finite element form; left support is a pin joint while the right support is a roller joint. The load was applied evenly distributed with constant intensity. The web wall of the I-beams is divided into seven compartments by transverse stiffening ribs. Thicknesses of the web plate of each beam were taken to be the same for all compartments. The forms of loss of local stability for various web thicknesses are shown. The change in the influence of force factors on local stability, with changing thickness of the web of the I-beam (section profile). So, for web thicknesses of 8, 9 and 10 mm in the studied steel beams, the loss of local stability occurs in the middle section, where the maximum value reaches bending moment My. While for I-beam with web thicknesses of 4, 5, 6, 7 mm in the beams under study loss of local stability occurs in the extreme compartment where the maximum values reach the transverse (shear) force Qz. The revealed change in the shape of the loss of I-beam’s web plate (vertical member of the I-section) stability may indicate a more significant effect of the shear force Qz for webs of smaller thickness. The analysis of the results is given numerical calculations.