Comparative Study of Deflection Equations for FRP RC Beams

The mechanical and bond characteristics of Fibre Reinforced Polymers (FRP) used as internal reinforcement for Reinforced Concrete (RC) elements result in larger deflections and crack widths compared to the conventional steel RC elements. Consequently, serviceability requirements may govern the design of such members. In the last 20 years, several approaches and codes of practice have been published to predict the theoretical deflection of FRP RC elements.

This paper analyses and examines the experimental deflection results of 145 concrete beams reinforced with FRP bars tested by several researchers, and compares their values with the theoretical values of 10 different approaches and design codes. All of the beam specimens were tested under a four point bending configuration and presented different reinforcement ratios and mechanical and bond properties of the FRP bars.

The objective of the paper is to investigate the suitability of the different approaches at different states of loading under the serviceability range. A statistical analysis is performed to evaluate the goodness of fit of each approach. The influence of several parameters as the level of load, the reinforcement ratio, or the modular ratio is analyzed and compared.