Finite element shakedown analysis of reinforced concrete 3D frames

In the present paper, the method proposed in [Casciaro R, Garcea G. An iterative method for shakedown analysis, Comput Methods Appl Mech Eng 2002;191:5761–92] for the shakedown analysis is used for the evaluation of the shakedown safety factor of reinforced concrete 3D frames subjected to a combination of varying loads. The FEM discretization for 3D frames is obtained subdividing the frame into rods and using a 3D beam finite element. Beam end-sections are used for checking plastic admissibility and for this reason the formulation models the interaction between the axial force and biaxial bending by a piecewise linearization of the elastic domain, for generic shape reinforced concrete sections. Concrete and steel are assumed to be elasto-plastic, and, for concrete, tensile resistance is ignored. The algorithm is described in detail and some numerical results, that show the efficacy and effectiveness of the proposed method, are reported and discussed.