An efficient plasticity-based model for reinforced concrete flat shells by a 4-nodes mixed finite element

Abstract. A 4-nodes flat shell Finite Element (FE) is formulated on the basis of an assumed interpolation of the stress and displacement fields in order to perform the elastoplastic analysis of reinforced concrete structures. The nonlinear material behaviour of the concrete is described through a confinement-sensitive plasticity constitutive model not requiring the often difficult calibration of several parameters but it is expressed in terms of only the uniaxial compressive strength of the concrete. The presence of steel reinforcement bars is accounted by defining additional material layers with a uniaxial von Mises elastoplastic behaviour. These different material responses are assembled through the shell thickness by numerical integration. Computational efficiency and accuracy are assessed by comparing the proposed shell strategy and other shell FE models by performing the step-by-step nonlinear analyses on a numerical test.