Numerical Study on the bending behavior of Reinforced Concrete Beams with kinked rebar

During the past earthquakes, the formation of plastic hinges in columns has given rise to global structural damage in moment resisting frame structures. If the plastic hinges are formed in the beams, the most suitable energy dissipating mechanism in structure will happen. The kinked rebar has locally curved regions (usually near the inflection points in beams) which can be gradually straightened under tension. Due to lower initial yielding flexural capacity compared with that of a cross section reinforced with traditional straight bars, the beam section reinforced with kinked rebars will yield first when the RC frame is subjected to seismic loading, and thus, the strong column-weak beam hierarchy can be realized. In this study, first the load-deflection behavior of a reinforced concrete beam was numerically simulated by ABAQUS software, and the reliability of the finite element model was verified by comparing with the experimental results of other researchers. Then, the load-deflection response of the RC beams with kinked bars which has two-step behavior were investigated and described in steps by using finite element modeling results. Finally, the control beam was used for further analyses to investigate the effect of important parameters including: concrete compressive strength, reinforcement ratio, and the ratio of beam span to depth on load-deflection curve of beams. Results showed that the ultimate bearing capacity of RC beam increases as the reinforcement ratio increases, however, it doesn’t have an important effect on the first yielding point. The increase of concrete compressive strength also contributes to greater initial yielding. In addition, the increase of beam span can have negative effects on the flexural behavior of RC beams with kinked bars, and reduce initial strength and stiffness of beams.Finally, the behavior of an internal connection including a beam with kinked rebar to the column was evaluated.