A Beam Finite Element for Shear-Critical RC Beams

The proposed beam finite element is capable of describing the response of reinforced concrete members under the interaction of axial force, shear, and bending moment. The element is based on a mixed formulation and does not exhibit the shear locking problems of displacement-based elements. The material model of the Modified Compression Field Theory by Vecchio and Collins (1986) was used to describe the biaxial response of the concrete at monitoring points across several monitoring sections along the element axis. With this model the proposed beam element is able to capture well the overall monotonic response of shear critical beams, while equally satisfactory agreement is obtained with local response measures, such as crack orientations. In spite of this promising agreement with experimental results the numerical performance of the material model was rather slow for the lack of a consistent tangent stiffness matrix. This fact coupled with the material model's inability to represent cyclic loading point out the need for a numerically consistent, robust and efficient constitutive model.