Evaluation of the Influence of Axial Loading on the Lateral Buckling Resistance of Tapered Laminated Composite I-Section Beam-Columns

In this research, the assessment of axial preloading influence on the lateral buckling capacity of laterally unbraced double-tapered I-section beam-column elements with symmetric laminated composite lay-ups under transverse load is presented. To this purpose, the classical laminated plate theory and Vlasov's model for nonuniform torsion are considered to derive the variational formulation for laminated composite beam-columns with varying I-section under axial and bending loads within the framework of elastic behavior. Then, the Ritz method is used for estimating the endurable buckling load. The accuracy of the adopted analytical technique is validated and compared with finite element simulations. Finally, a parametric investigation is conducted to peruse the influence of web and flanges tapering ratios, load height parameter, laminate stacking sequences, fiber composite materials, and axial force on the lateral buckling resistance of cantilever double-tapered beam-column with I-section. Additionally, in the presence of a known axial force, the interaction between beam lateral stability strength and column flexural buckling is examined and discussed.