Buckling Of Stepped Columns & Moment Amplification Factor Of Columns In Frame-Shear-flexural Bracing Systems

This paper is composed of two partsI Buckling of stepped columns considering the effect of shear deformationStepped columns are widely used in medium and heavy-duty crane industrial workshops.The effective length factor of a stepped column is decided by solid column at present. But when deciding the section inertia moment of the column below, coefficient 0.9 is used, and after effective length factor μ. is obtained, equivalent slenderness ratio is used to consider the effect of shear deformation. Thismethod may consider the effect of shear deformation twice.There are no documentations that present the difference between the method above and the exact method at present. Chapter2 of this paper discusses the buckling of stepped columns considering the effect of shear deformation by exact theory, and the results are compared with the results obtained from the method above.II Moment amplification factor of columns in frame-shear-flexural bracing systems In multi-story buildings, bracing systems are usually used to enhance the structure overall stiffness.Frame-bracing structure is a type of dual system. In practice, the bracing systems are mostly shear-flexural ones, where the shear and flexural deformation must be considered simultaneously.Under the lateral and vertical load, considering the P - A effect, the moment in columns will be amplified, and the amplification factor should be considered in design.Chapter3 of this paper analyzes the moment amplification factor of columns and the structural displacement amplification factor in frame — shear-flexural bracing systems based on some documentations and concerned studies, and an approximate formula is proposed. The factors are also calculated by FEM method and compared with the formula results. The models built in ANSYS include various types such as changes in cross section, changes in stiffness, changes in axial force, different loading method and so on.