Optimization of flexure environment of concrete beams reinforced with fibre-reinforced plastic rebars

Abstract

This study presents the optimum design and behavioural assessment of simply supported beams subjected to uniformly distributed loads and reinforced with fibre-reinforced plastic rebars. A formal optimization model is developed in which the cost per unit length of the beam represents the objective function to be minimized, and is expressed in terms of two design variables (the effective depth and the reinforcement ratio). The constraints on the optimization model are in accordance with the ACI code provisions. They include flexural demand due to the imposed loads and the serviceability requirements that specify an upper limit on the deflection of a beam under service loads. The optimization process is illustrated with the help of a beam example reinforced with glass fibre-reinforced plastic (GFRP) rebars. The results are compared with those of its counterpart reinforced with conventional steel bars. A parametric study to assess the influence of parameters such as the ultimate compressive strength of the concrete, span of the beam and cost of GFRP rebars is presented.