Finite Element Studies of Shear-Critical R/C Beams

Abstract

A finite element model is presented which enables the analyst to trace the history of strains, stresses, and crack propagation in reinforced concrete beams subject to a plane state of stress, for a monotonic increase of external load. Concrete nonlinear behavior is assigned analytically, as resulting from biaxial tests. Steel-concrete interaction is described through experimental nonlinear bond-slip curves. Concrete cracking is taken into account by considering the element unable to sustain stresses in a direction normal to the crack, but capable of transmitting friction forces parallel to the crack itself, through a value of the shear stiffness fixed on the basis of experimental information on aggregate interlock. An iterative solution procedure is used. The effects of updating the tangent stiffness matrix at each iteration are considered, and provisions are included to prevent the occurrence of numerical ill conditioning. The validity of the method is demonstrated against a well-controlled set of experiments on reinforced concrete beams.