A novel finite element formulation for beams with composite cross-section

The development of an exact one-dimensional beam finite element with composite cross-section is proposed. The element formulation is developed starting from the analytical solution provided in the recent literature, without the need to introduce any shape function for the interpolation of the element displacements and rotation fields. Moreover the formulated finite element allows to solve cases involving beams characterized by different axial displacements of the two cross-section parts, i.e. it offers the possibility of taking into account the lack of continuity of the axial displacement of one or both elements constituting the cross-section. The developed finite element can be simply used by defining its geometrical characteristics and the inertial properties of the two cross-section’s elements, together with the interface shear stiffness of the connection system. The proposed finite element is applied for the simulation of some representative cases and the obtained solutions are compared with that provided by theoretical ones; finally – by exploiting the possibility of accounting for the axial discontinuity of the element – simulation of composite beams allowing the failure of the upper part of the cross-section (typically constituted by a concrete slab) is performed.