Improved design-oriented confinement models for FRP-wrapped concrete cylinders based on statistical analyses

• A large experimental database of concrete cylinders wrapped with unidirectional FRPs was compiled from the literature.
• Performance of existing strength and strain confinement models is evaluated.
• A general regression analysis procedure is applied to evaluate various forms of improved models.
• Based on statistical indices, the best strength and strain confinement models are proposed.
• A parametric study is performed using the proposed models.

This paper introduces improved design-oriented confinement models for cylindrical concrete members wrapped with fiber reinforced polymer (FRP) composites based on a rigorous statistical evaluation of a large database. As most of the existing design-oriented models for ultimate condition of FRP-confined concrete were developed based on limited experimental data points, a large experimental database of 518 cylindrical concrete specimens wrapped with unidirectional fabrics in the hoop direction with reported actual rupture strain of the wrap was compiled from the literature. The database is used to evaluate the performance of major existing strength and strain models. Then, using a general regression analysis, different forms of models are examined to obtain the best fit, and the performance of the models is compared to the existing models using the database. Based on two different statistical indices, the coefficient of determination (R2) and the Root Mean Square Error (RMSE), the best performing strength and strain models are proposed for use in design applications. A parametric study is also performed on fiber type, cylinder diameter, concrete strength, and FRP wrap thickness, elastic modulus, and strength using the proposed models.