An Equation for the Effective Moment of Inertia for Frp-reinforced Concrete Beams

The deflection of concrete beams reinforced with GFRP bars is higher than those which are reinforced with steel bars. The purpose of this paper is to propose a new equation for estimating the effective moment of inertia in FRP-reinforced concrete beams. This will be accomplished by using experimental results and the genetic algorithm approach. Genetic algorithm is used for optimizing the error function between the experimental and analytical values obtained for the effective moment of inertia. Experimental data points were obtained from forty six FRP-reinforced concrete beams tested by different researchers and nine GFRPreinforced concrete beams tested by the authors. These data points were selected as discrete points on the load-displacement curves of fifty five test specimens. These were between cracking and service levels of loading. Studies show that the intensity of the load, the reinforcement ratio and the elastic modulus of the FRP bars are most important parameters in calculating the deflection. In this paper, the effects of all aforementioned variables on the effective moment of inertia are taken into account. The results show that deflections predicted by the proposed equation are in good agreement with experimental values.