Displacement-based nonlinear finite element analysis of composite beam–columns with partial interaction

Several structures employ members with a deformable connection between two components, also known as partial interaction or interlayer slip. Classical examples include composite steel–concrete beams and glued or nailed timber beams. Most of the numerical research in this topic, however, has been focused on composite beams with material nonlinearity. In some situations these members may be subjected to compression and bending, for which 2nd order effects should be taken into account. The purpose of this work is to develop and test a displacement-based finite element model for the nonlinear material and geometrical analysis of composite beam–columns with interlayer slip. The finite element is based on a total Lagrangian description, in the context of large displacements, small strains and moderate rotations. The robustness and accuracy of the proposed scheme is verified against examples from the literature.