Experimental Evaluation of Axial Behavior of Strengthened Circular Reinforced-Concrete Columns

Abstract

Insufficient or deteriorating reinforced-concrete piers in many existing bridges are required to be strengthened using economical, fast, and efficient methods. Currently, only a few methods can be used to strengthen circular columns. Steel jackets and fiber-reinforced polymer (FRP) composites are the two commonly used methods. In this study, along with these two strengthening methods, concrete jackets reinforced with spiral rebar, welded wire fabric (WWF), and a new steel reinforcement called PCS are investigated under different axial-load applications. Fifteen identical specimens were constructed, strengthened, and tested: one column with no strengthening; three columns strengthened with FRP; two with steel jacketing; and nine with concrete jacketing (two with WWF, three with spiral rebar, and four with the new reinforcement). The bare or unretrofitted specimens had a 152 mm (6 in.) diameter, while the outside diameter of concrete-jacketed specimens was 254 mm (10 in.). Effectiveness of each strengthening method in increasing the stiffness, axial capacity, and displacement ductility was investigated using the experimental data.