Investigation of Pre- and Postcracking Shear Behavior of Prestressed Concrete Beams Using Innovative Measuring Techniques

Until now, no unified theory exists that is capable of fully describing the complex behavior of reinforced concrete elements subjected to shear. On the contrary, one may find recent research results contradict each other. Using innovative measuring techniques, the pre- and postcracking shear behavior of concrete beams is studied giving insight to the shear resistance mechanism of reinforced concrete beams. For studying the precracking behavior, the method of laser-interferometry is applied. It is shown that nonlinear stress distributions take place before the formation of visible cracks, thereby influencing the cracking angle. The photogrammetry is applied to study the postcracking behavior. The measured displacement components of the crack edges are used to estimate the shear transferred across the cracks by shear friction. It will be shown that for beams with low or high shear reinforcement ratios, the amount of shear force transferred across cracks by shear friction is negligible.