Prediction of the effective moment of inertia for concrete beams reinforced with FRP bars using an evolutionary algorithm

Abstract

The previous studies on the bending behavior of Fiber Reinforced Polymers (FRP) Reinforced Concrete (RC) beams proved that there is a distinct difference between the cracking and deflection behavior of these structural members and conventional RC beams with steel reinforcing rebar. Accordingly, the existing relations for the prediction of deflection and crack width of RC members cannot be used for serviceability controls of FRP-RC beams. The present study proposes new and more accurate predictive relations for the effective moment of inertia and the crack width of GFRP-RC beams using a collection of experimental test results from literature an Evolutionary Algorithm (EA) called Multi-Expression Programming (MEP). An EA is a subset of generic population-based metaheuristic optimization, which performs mechanisms inspired by biological operations to find the best solutions for different types of approximating problems. Numerical evaluations proved that the proposed relation for the effective moment of inertia has higher accuracy than the other existing relations with an R2 value of 0.49 and RMSE, MAE, and IAE error indices of 0.31, 0.72, and 0.51. The proposed relation for the crack width also outperforms the other existing counterparts. Since the proposed relations are developed based on the results of the four-point bending test on simple beams, the accuracy of the proposed relation for the effective moment of inertia was also compared with the experimental and numerical results for continuous beams, which again verified the high accuracy of the proposed model. In addition to the experimental database, a numerical model is also developed to verify the accuracy of the suggested models. The attained results demonstrate considerably higher accuracy of the proposed relations in comparison with the other existing counterparts.