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Abstract To avoid a brittle failure of reinforced concrete (RC) frame, the ductility of beams has an important role during earthquake. The calculation of the accurate values of ductility of confined RC beams is complicated, and therefore, a direct and accurate approach is necessary. This study presents two approaches to predict the curvature ductility of RC beams using results of a new method. In the new method, a procedure was developed that curvature ductility of 250 confined and unconfined RC beams were calculated based on actual characteristics of a confined and unconfined compression concrete. In the first approach, an equation was proposed to predict curvature ductility of RC beam by using nonlinear regression based on result of 250 beams. In the second approach, an ANN model was trained to predict curvature ductility of RC beam based on result of 250 beams. An experimental database containing 51 RC beams as flexural test was used to validate the proposed equation and ANN model. A statistical analysis was then performed to evaluate and compare the proposed equation and ANN model for tested RC beams. The statistical analysis results show that ANN model can predict the curvature ductility of RC beam with slightly less scatter in comparison with the proposed equation. Overall, both approaches can predict curvature ductility of RC beam by a proper accuracy.
Keywords RC beam Confinement Curvature ductility Nonlinear regression Artificial neural network
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1 Introduction
In seismic regions, ductility is an important factor for design of concrete members under flexure and it leads to increase the capacity of plastic displacement. As a result, the inertial forces imposed to structures can be decreased (Penelis and Penelis 2014). In other words, energy dissipation capacities of reinforced concrete (RC) structural members depend on the level of ductility which is described in various ways. The ductility of reinforced concrete beams is very important, because, in the design of RC structures with "strong column-weak beam" approach, the beams should yield before the columns yield and the beams require to have a sufficient flexural ductility such that the potential plastic hinges in the beams are able to maintain their moment-resisting capacities until the columns fail.
Results of previous research show that parameters that affect the flexural...