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This paper treats the distortional and shear deformation effects on the elastic lateral torsional buckling of thin-walled box beam elements, under combined bending and axial forces. For the purpose, a geometrically nonlinear kinematic model in conjunction with higher order theory is adopted. Thus, Ritz's method is applied in order to discretize the governing equilibrium equations, these ones are nonlinear and strongly coupled. This model provides the lateral buckling resistance by requiring the singularity condition of tangent stiffness matrix. Many illustrative applications are considered for thin-walled box beams under lateral load combined to axial force. The proposed method is simple and gives accurate results when compared to finite element simulations using Abaqus software. The ability of the classical stability solution to predict the maximum design moment is questioned in this study.

International Symposium on Light Alloys and Composite Materials
UHAKS

Abdelkader SAOULA Sid Ahmed MEFTAH Abdelrahmane B.BENYAMINA

The elastic lateral torsional buckling behaviour of doubly symmetric web tapered thin-walled beams is investigated in this work. For the purpose, a non-linear model is developed in large torsion context according to a new kinematics proposed model. Firstly, the elastic equilibrium governing equations are carried out from the stationary condition. Secondly, a numerical model based on Ritz's method is investigated for the lateral buckling stability of tapered thin-walled beams with doubly symetric cross-sections and simply supported boundary conditions. Total potential energy is derived for an elastic behavior from strain energy and work of the applied loads. The effects load eccentricities is considered in the study. The lateral-torsional equilibrium equations and the associated boundary conditions are obtained from the stationary condition. In presence of tapering, all stiffness coefficients are not constant. The Ritz's approximation is then used to solve the differential equations of tapered thin-walled beam with variable geometric parameters. The lateral buckling loads are determined by solving the eigenvalue problem of the obtained algebraic system. Several numerical examples of tapered thin-walled beams are presented to investigate the accuracy and the efficiency of the method. The obtained results are compared with finite element solutions using ABAQUS software and other available numerical approaches. It is observed that suggested method can be applied to stability of beams with constant cross-sections as well as tapered beams.

International Symposium on Light Alloys and Composite Materials
UHAKS

Abdelrahmane B.BENYAMINA Abdelkader SAOULA