Cost-optimal design of flexural concrete beam reinforced with FRP reinforcements

Abstract

Because of the non-ductile nature of FRP reinforcement, the convention of designing cross-sections with the flexure strength limited by reinforcement yield, as for steel, is not adequate. Although ACI 440.1R-15 gives easily fetched explanations on how to design FRP reinforced concrete (FRPRC) sections for flexure, an understanding of the different parameters economic influence is required for FRP to be a competitive alternative to steel. In this paper, an analytical tool for cost-optimally analyzing and designing FRPRC cross-sections according to ACI 440.1R-15 is presented. To this aim, by optimizing the functions for flexural strength and for the approximated price pr. meter of a cross-section with respect to both fiber cross-section area and effective depth of concrete cross-section a formula for the most economical ratio of these parameters in regard to flexural strength is presented. For a given FRP and concrete type, the optimal ratio proves to be the same for all desired flexural capacities, and can for rectangular cross-sections be presented as a function of the cross-section width.