Deterioration Mechanism of Shear-Resisting System in RC Beam Subjected to Reversed Cyclic Loading after Flexural Yielding

Based on cyclic tests of RC beams that failed in flexural-shear without yielding of the transverse reinforcement, a mechanism controlling flexural shear failure is proposed. This mechanism, which is associated with ‘Error Catastrophe’ known as a theory of aging, was observed in the hinge region of the beams. The results of experimental testing indicate that a shear-resisting system forms in the flexural hinge region of a RC beam subjected to monotonic loading. Under reversed cyclic loading, the shear-resisting system temporarily disappears as cracks open and then is rebuilt as cracks close. A flexural shear failure occurs when the shear resisting mechanism is not rebuilt upon load reversal. What inhibits the rebuilding process and, ultimately, results in a failure to rebuild, is “errors” in the rebuilding process. These errors accumulate each time the shear-resisting system is rebuilt, and when the errors exceeded a certain tolerance, failure due to the malfunction of the rebuilding occurs.