ممان اینرسی مؤثر تیرهای مسلح شده با میلگردهای FRP

Abstract

Concrete beams reinforced with glass fiber reinforced polymer (GFRP) bars exhibit large deflections and crack widths as compared with steel reinforced concrete beams due to the low modulus of elasticity of GFRP bars. Different studies show that ACI 318 equation for the effective moment of inertia Ie does not predict deflection well for FRP reinforced concrete beams. The purpose of this paper is to propose new equations for estimating the effective moment of inertia of FRP reinforced concrete beams based on genetic algorithm and experimental results. Genetic algorithm is used for optimization of error function between experimental and analytical responses. In the experimental part of the study, nine beam specimens were manufactured and tested. The parameters of reinforcement ratio and concrete compressive strength were selected as the variables for the beam specimens. Also fifty five beam specimens tested by other researchers were used for experimental database. In this paper, the effect of elastic modulus of FRP bars, reinforcement ratio and the applied level of loading on the effective moment of inertia is taken into account. In addition, the proposed equations are compared with different code provisions and the existing models for predicting deflection of FRP reinforced concrete beams. Also, the calculated values by the proposed equations are compared with different test results. The experimental results correlated well with the values predicted by the proposed equations especially in high reinforcement ratios and high levels of loading.