Research on Cracking of Reinforced Concrete Beam and Its Influence on Natural Frequency by Expanded Distinct Element Method

Abstract

A distinct element model was proposed to simulate cracking in a reinforced concrete beam, and the influence of cracking on natural frequency was analyzed. Hexagonal block and tensile-shear failure criteria were implanted into the framework of the expanded distinct element method to determine two-dimensional cracking and to analyze the crack growth of the reinforced-concrete beam. Experimental tests were also carried out to verify the numerical simulation results. Numerical and experimental results show that at the cracking initiation stage, cracks appear below the loading points because of concentrated tensile stresses and grow upward. When these cracks penetrate three-quarters of the beam, cracks open in the bottom and gradually curve toward the loading points. Cracks caused by shear failure occur in the top of the beam. The beam fails because of a yielding of the longitudinal tensile reinforcement bar. Cracking and yielding of longitudinal tensile reinforcement can be identified based on a continuously descending natural frequency.