An efficient materially nonlinear finite element model for reinforced concrete beams based on layered global-local kinematics

In this study, a finite element model with low degrees of freedom is presented for the materially nonlinear analysis of reinforced concrete (RC) beams. The kinematics considered for the RC beam is based on a layered global-local (LGL) theory. Unlike the classical one-dimensional (1D) beam kinematics (e.g. Euler-Bernoulli's and Timoshenko's beam theory), the effects of shear deformation and normal flexibility of the RC beams are considered in the formulation of the present LGL theory. No shear correction factor is needed in the present LGL theory. The LGL theory has only one extra displacement variable more than Timoshenko's beam theory. Elastoplastic and fixed smeared crack models are considered for modeling the material nonlinearity of the reinforcing steels and cracked concrete, respectively. The results obtained from the present nonlinear finite element model are compared with experimental and numerical results. Comparisons show that the present model gives accurate results at a low computational cost.