NONLINEAR FINITE-ELEMENT ANALYSIS OF CONCRETE DEEP BEAMS

The salient features and concepts of a model developed recently are reviewed. The parameters of the model arc the peak compressive stress of concrete, initial elastic modulus, and tangential Poisson's ratio. The peak stress is assumed equal to the compressive strength of standard cylindrical concrete specimens, the Poisson's ratio is calculated by a proposed empirical equation. Predictions of the model compare favorably with experimental data on small specimens reported by various investigators. The model was implemented with the finite element method and several deep beams were analyzed and compared with experimental data. The strain softening characteristics of the model allowed satisfactory predictions of the response up to failure. The areas where cracks developed and the propagation of the crack zones up to the final collapse of the beam were predicted and compared with experimental data. Finally the model was used to predict the behavior of square panels subjected to in-plane axial and shear forces as well as pure shear. The predictions are satisfactory.