LAUSR

Reversed cyclic loading tests of two circular hollow RC piers were conducted in this study to investigate the effect of different amounts of inner and outer circular hoops on their flexural behavior. The test results showed that the column with a smaller amount of inner circular hoops presented better flexural response than the as-built column with an equal amount of inner and outer circular hoops. Also, the demand developed on the inner circular hoops was smaller than the outer one within the plastic hinge regions, which verified that using a smaller amount of inner circular hoops was reasonable and effective. By examining the confining stress experienced by the concrete in the radial and circumferential directions based on a detailed theoretical analysis, a modeling approach was proposed to take the confinement effect in circular hollow RC piers into consideration. The proposed modeling approach was validated through comparisons with the experimental study and satisfactory agreement was found.