A two-field mixed variational principle for partially connected composite beams

This paper presents a new beam-column element for the nonlinear analysis of partially connected composite beams. The element is based on a two-field mixed variational principle, where both variables, forces and deformations, are simultaneously approximated within the element. The model neglects uplift and frictional effects. Shear connectors are modeled using a distributed interface element. Two algorithms for the proposed model are presented. Stability of both algorithms is discussed. Numerical examples that clarify the advantages of the proposed model over standard models based on the principle of minimum potential energy, and discuss the different alternatives of the order of interpolation functions are presented. The studies prove the superiority of the mixed model. (C) 2001 Elsevier Science B.V. All rights reserved.