The statistical evaluation of design methods of the load-carrying capacity of flexural reinforced concrete elements strengthened with FRP

This article presents a statistical analysis of the design methods for calculating the load-carrying capacity of reinforced concrete elements in flexure strengthened with external FRP reinforcement. To perform calculations a database of experimental research has been created. Calculations of the load-carrying capacity were performed following the ACI440.2R-08, fib bulletin 14, TR55 recommendations. Distribution of experimental and theoretical results was determined on the basis of Wilk–Shapiro test. The evaluation of design methods was done by testing the statistical hypotheses on the difference of the means of the ratio between the experimental and theoretical results. Confidence intervals of the ratios of the experimental and calculated load carrying capacity were also calculated. In order to assess the accuracy of the design methods it is suggested to calculate the coefficient of confidence.