Micro Mechanical Measurement of Concrete Strain to Evaluate Principal Strain Distribution in RCC Moderate Deep Beams across its Width and Depth

This paper investigates the distribution of principal strain by micro mechanical measurement of concrete axial strain in Reinforced Cement Concrete (RCC) moderate deep beams across its width and depths for various span-to-depth ratios. A complete shear deformational behavior along with load-deflection response, crack patterns and modes of failure were studied experimentally. Twelve beams were tested and results of principal strain were plotted. Nature of principle tensile strain distribution was found similar to elliptical pattern of distribution along the line joining the load and the support point. The assumption of plane stress condition underestimates the significance of the small compressive or tensile stresses develop in the transverse direction from incompatible response of consecutive concrete elements subjected to different states of stress. Therefore, it was considered that the modes of shear failure are associated with multi-axial stress conditions which exist in the region of the paths along which the compressive forces are transmitted to the supports.