Finite Element Analysis of Reinforced Concrete beams subjected to combined actions

Abstract

An enhanced multi-fiber beam element suitable for the analysis of reinforced concrete members subjected to combined loadings is presented. The model is developed using displacement-based formulation with small displacement assumption. The section kinematics is based on the kinematic assumptions of a two-node Timoshenko beam and enhanced by introducing additional degrees of freedom at each section in order to take into account the warping phenomenon. A system of fixed points is created and interpolated by Lagrange functions and polynomials. In order to take into account the contribution of stirrups, a discretization of control sections into different regions following its material response is applied. As a result, the basic assumptions of the Modified Compression Field Theory with a secant-stiffness formulation is used to represent the constitutive material model for reinforced concrete. The model is validated by comparing to the theoretical formulations and several experimental tests. The simulations include a variety of monotonic load conditions under bending, shear and torsion for specimens with rectangular section.