Confinement model for circular concrete columns transversely reinforced with GFRP spirals and hoops

In many applications, bars made of Glass-Fiber-Reinforced-Polymer (GFRP) have successfully replaced steel rebars and become a practical substitute for shear and flexural reinforcement in reinforced concrete (RC) members. Nevertheless, the behavior of GFRP-RC columns may differ considerably from steel-RC columns because of the variations in the mechanical properties of the two types of reinforcement. In this study, a database of 95 experimentally tested circular columns is collected and utilized to assess the confined strength of GFRP-RC columns. The database has been filtered based on the slenderness ratio to avoid the slenderness effect in the analysis. The filtered database has been used to assess the prediction accuracy of several widely adopted confinement models in terms of and to develop a new proposed model. The influence of all factors affecting the peak stress in confined concrete is considered in this study. The analysis shows a linear relationship between lateral confinement and the increase in axial stress. The proposed confined compressive stress model provides the highest statistical correlation to the experimental data. In addition, the trend line obtained through regression analysis of the concrete strain is in good agreement with the experimental results.

Automated summary

Glass-Fiber-Reinforced-Polymer (GFRP) bars have successfully replaced steel rebars in many applications and become a practical substitute for shear and flexural reinforcement in reinforced concrete (RC) members. However, the behavior of GFRP-RC columns may differ from steel-RC columns due to variations in the mechanical properties of the two types of reinforcement. This study collects a database of 95 experimentally tested circular columns to assess the confined strength of GFRP-RC columns and evaluates the prediction accuracy of confinement models.