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.

在本研究中，评估了轴向预载对具有对称层合复合材料叠层的横向无支撑双锥形工字型梁柱单元在横向载荷下的横向屈曲能力的影响。为此，考虑经典层合板理论和Vlasov非均匀扭转模型，推导弹性行为框架内轴向和弯曲荷载作用下具有不同工字截面的层合组合梁柱的变分公式。然后，采用Ritz法估算耐屈曲载荷。验证了所采用的分析技术的准确性，并与有限元模拟进行了比较。最后，进行参数研究，以仔细研究腹板和翼缘锥度比、载荷高度参数、层合板叠层顺序、纤维复合材料及轴力对工字型悬臂双锥梁柱抗侧屈曲性能的影响 此外，在存在已知轴向力的情况下，检查和讨论了梁横向稳定性强度和柱弯曲屈曲之间的相互作用。