Comparison and Enhancement of Design Procedures for Guideline Expressions to Predict the Compressive Capacity of FRP-Wrapped Concrete Members

The FRP wrapping of reinforced concrete columns is a simple way to increase the axial load capacity of such members with substandard concrete quality. A total of 2197 specimens were collected as a database to discuss the efficiency of predicting axial compressive strength of FRP-wrapped concrete columns according to several national and international guidelines. Various aspects of the database, including fiber type, unconfined strength and specimen geometry used to investigate the guidelines, and results are presented in terms of averages, standard deviations, and ratio of overestimated specimens. The performance of these expressions was compared with one another based on these statistical results and graphs, and those that captured the behavior best were identified for specific subsets. Recognizing the expressions’ inadequacy in capturing efficiency improvements related to radius to area and confinement ratios, some improvements in the form of coefficients for lateral confinement stress in the Turkish Building Earthquake Code were introduced, specifically for certain subsets.