A beam element suitable for layered structures is such that its nodes can be connected flexibly to those of another element by applying proper spring elements between the appropriate nodes. The three degrees of freedom at the end nodes of the ordinary element are therefore separated into three nodes, each having now only one degree of freedom, axial or transverse displacement (Figure 1.). The top and bottom nodes, ’ti’ and ’bi’ allow for displacements in the direction of the
element axis and the middle node, situated on the centroidal axis, deflects transversely. Different configurations can be produced for the axial nodes, depending on the structural system for which the element is intended. The coefficients of the stiffness matrix are always derived according to the location of these nodes.