Buckling strength of fixed end columns braced continuously with varying axial force: Flexural buckling of compressive flange of H-shaped steel in which beam web is considered as continuous bracing

The objective of this study is to clarify the influence of out-of-plane resistance of a beam web. H-shaped beams are connected to columns which have torsional stiffness such as square steel tubes and the out-of-deformation of the upper flange is restrained by floor slabs. The lower flange is modeled as a fixed end column subjected to varying axial force and restrained by the beam web continuously. The buckling strength and the effective length factor of the column are calculated by using the Rayleigh-Ritz method and analytical parameters are stiffness ratio and axial force ratio. The relation between the stiffness ratio and the effective length factor are presented and it is shown that the influence of the torsional stiffness of a lower beam flange to these relations is small. The ratio of the beam length to width of the flange which can expect the yield strength of the beam flange subjected to compressive force is presented.