Stress-strain relations for cracked tensile concrete from RC beam tests

A method for determining the stress-strain relations for concrete form short-term flexural tests of reinforced concrete members is proposed. The method is based on the smeared crack approach. Average stress-strain relations for concrete in tension (including the descending branch) and in compression are computed from experimental moment-average strain and/or moment-curvature curves. Computation of stress-strain relations is performed incrementally for the extreme surface fibers, and is based on a novel idea of using the previously computed portions of the stress-strain relations at each load increment to compute the current increments of the stress-strain relations. The proposed method has been applied to some experimental data reported in the literature. Average stress-strain curves for concrete in tension, where cracking, bond, and shrinkage effects were taken into account in an integrated manner, have been computed for beams with various depths, reinforcement ratios, and rebar diameters. These and other parameters affecting the shape of the stress-strain curves (or tension stiffening effect) have been discussed.