Prediction of effective moment of inertia for hybrid FRP-steel reinforced concrete beams using the genetic algorithm

The use of Concrete beams reinforced with a combination of fiber reinforced polymer (FRP) and steel bars has increased dramatically in recent years, due to improvement in strength and flexural ductility simultaneously. In this paper, we proposed a new equation for estimating the effective moment of inertia of hybrid FRP-steel reinforced concrete (RC) beams on the basis of the genetic algorithm and experimental results.The genetic algorithm is used to optimize the percent error between experimental and analytical responses. In the proposed equation, additional coefficients are considered in order to take into account the specific properties of FRP bars. The effects of the elastic modulus of FRP and steel bars, the hybrid reinforcement ratio, Af /As, and the different level of loading on the effective moment of inertia has been considered.These coefficients are used to modify Branson’s equation to compute the effective moment of inertia of concrete beams reinforced by FRP and steel bars. Comparison between the experimental and predicted results showed the adequacy of the model used in predicting the effective moment of inertia, and deflection of hybrid – RC beams.