Experimental Study on Direct Tensile Behavior of Concrete under Various Loading Regimes

An experimental study of the stress-strain behavior of concrete under monotonic and cyclic uniaxial tensile loading is carried out. Complete monotonic and cyclic stress-strain curves are obtained by six various loading regimes. The uniqueness of envelope curve is validated for the concrete subjected to monotonic and cyclic tensile loading. Residual strain accumulation and the change of initial elastic modulus were used to evaluate damage accumulation and stiffness change with the increasing of cyclic loads. The stress drop versus number of cycles to specified maximum strain is investigated and the result shows that the rate of stress drop decreases as the cycling continues and finally tends to stable. The proposed semi-empirical mathematical expression model to simulate the stress-strain curve for unloading and reloading has been developed by fitting the experimental stress-strain curves. The analytical results show a good agreement with the experimental results for all loading regimes.