Finite element analysis for buckling of two-layer composite beams using Reddy’s higher order beam theory

• A new finite element for higher order shear deformable composite beams is proposed.
• All the interpolations of basic unknowns are free of penalty coefficient.
• Buckling analyses have been conducted with the presented and classic beam theory.
• Parametric study explores the shear effects on the mechanical behavior.

In this paper, a two-layer partial composite columns model is built based on Reddy׳s higher order beam theory, and two novel displacement based finite elements for this and Timoshenko composite beams are respectively formulated by means of the principle of minimum potential energy. Subsequently, the buckling analyses of pinned–pinned and clamped–guided composite columns are performed using the proposed finite elements, and the results are compared with those obtained by plane stress model, Timoshenko and Newmark composite beams model respectively. The superior quality of Reddy composite columns model over Timoshenko composite columns model and the correctness of the proposed Timoshenko composite columns model are demonstrated by the numerical comparison. Finally, the parametric study explores effects of parameters including stiffness of shear connectors, span-to-depth ratios, Young׳s modulus ratios and sub-layer׳s depth on the buckling load. The discrepancies between the performance of higher order and Timoshenko composite columns have also been numerically investigated.