Nonlinear analysis of reinforced concrete slabs using a quasi-3D mixed finite element formulation

This study presents an efficient quasi-3D mixed finite element (MFE) formulation for the materially nonlinear analysis of reinforced concrete (RC) slabs based on a refined layered global-local plate theory. The cross-section of the RC slab is divided into a series of concrete and steel layers. Each layer is treated as a plate structure and mechanical properties of the steel and concrete materials are individually applied to each layer. In addition to unknown variables of the displacement field, out-of-plane stress components are also assumed as independent field variables in the presented MFE formulation. It makes it possible to obtain the out-of-plane shear stresses at each node directly from constitutive equations with the enough accuracy. A four-node rectangular element ensuring the C1-continuity is used for discretizing the domain of the RC slab. The governing equations are derived based on a partially mixed-field variational principle. The accuracy and efficiency of the presented MFE have been investigated through some benchmark examples. Numerical tests show that the presented MFE yields results with sufficient accuracy at a low computational cost.