A study of parameters in the diagonal tension cracking of concrete beams

This is a study seeking to gain additional information concerning the diagonal tension cracking of reinforced concrete beams without web reinforcement. The parameters which affect diagonal tension cracking have been defined by previous studies; however, much work needs be done in order to predict accurately the magnitude and influence on behavior of these parameters. The study was conducted in two phases; an analytical investigation of the amount of shear transferred across the face of a diagonal tension crack by the longitudinal steel and of the influence which the crack starting point has on tensile cracking, and an experimental investigation of the ratio of shearing stress to flexural stress at the root of a diagonal tension crack. The results of the analytical investigation confirm the importance of including the "dowel force" in any analysis of the behavior of reinforced concrete beams without web reinforcement when subjected to combined shear and bending moment. New insight was also gained as to the effect of crack starting point on crack development, and hence on beam behavior. This study included both beams of normal weight and lightweight structural concrete, and the results of the computations made in this study show about the same amount of accuracy for beams of both types of concrete. The experimental investigation showed that the ratio of shearing to flexural stress at the root of a crack was greater than previously assumed and that this ratio seems to be inversely proportional to a function of the uncracked depth of the beam