The Influence of the Internal Forces of the Buckling Modes on the Load-Carrying Capacity of Composite Medium-Length Beams under Bending.

The distribution of the internal forces corresponding to the individual buckling modes of lip-channel (LC) beams is investigated using the Semi Analytical Method (SAM) and the Finite Element Method (FEM). Channel section beams made of 8-layered GFRP (Glass Fiber Reinforced Polymer) laminate with three different layer arrangements were considered. The effect of the internal forces on the non-linear first-order coefficients corresponding to the interactive buckling was also studied. Moreover, distributions of the internal forces corresponded to the loading, leading to structure failure for which the load-carrying capacity was determined. The results indicated a high influence of the Nx internal force component on the buckling loads and load-carrying capacity of the LC-beams.