Quantifying the flexural rigidity of FRP RC beams for serviceability using mechanics

Abstract

The deflection of steel RC beams is a major design consideration and becomes of particular importance for FRP RC beams as the modulus of the reinforcement can be much lower than that for steel. Furthermore, the elastic modulus and the bond characteristics of the FRP reinforcement can vary widely in contrast to that of steel. Current procedures for quantifying the short term serviceability deflection of steel RC beams rely on an empirical approach for determining an effective flexural rigidity. Being empirically based these effective flexural rigidities can only be used for steel reinforcement, and if extended to FRP reinforcement a very large amount of testing to cover the wide range of moduli and bond associated with FRP reinforcement would be required. To reduce the amount of testing a mechanics based approach is described for deriving the equivalent of the effective flexural rigidity that is required for design. It is shown that this approach can cope with any type of FRP and, hence, should be useful in developing generic design procedures for determining the deflection of FRP RC beams and slabs.