Analysis of reinforced and thin-walled structures by multi-line refined 1D/beam models

• The multi-line approach to the analysis of slender bodies is introduced.
• Structures are modeled via multiple beam-lines containing refined 1D elements.
• Compatibility at beam-line interfaces is imposed through Lagrange multipliers.
• Reinforced and thin-walled structures are considered.
• The multi-line models are highly efficient for the analysis of reinforced structures.

This paper focuses the attention on the use of appropriate combinations of refined one-dimensional (1D) beam theories to analyze thin-walled, reinforced structures. The cross-section of a slender body is seen as the sum of different sub-domains. Each sub-domain is subsequently used as the cross-section of a beam discretization. Displacement variables are then expanded around the beam axis of each sub-domain by using refined 1D models which are based on the Carrera Unified Formulation. The order of the beam elements can vary in different sub-domains. This subdivision has been called “multi-line” as opposed to the “one-line” approach of classical beam theories. 1D compatibility conditions of the displacements at selected points of the sub-domain interface boundaries are imposed by using Lagrange multipliers. Various problems have been analyzed to highlight the advantages and disadvantages of the present multi-line approach. It is concluded that the multi-line approach appears very effective in the case of thin-walled sections made by locally connected walls as well as in the case of reinforced structures.