Seismic performance of circular hollow concrete columns

Four circular hollow reinforced concrete columns were tested under quasi-static reversed lateral loading to investigate their seismic performance. The effects of the wall thickness ratio and confinement configuration on their seismic performance were studied, and the applicability of seismic ductility design requirements on circular hollow concrete columns was examined. The test results showed that circular hollow concrete columns with a single layer of transverse reinforcement presented limited ductility, and their displacement ductility improved as the wall thickness ratio increased. Two layers of transverse reinforcement with crossties allowed circular hollow concrete columns to present excellent seismic performance. However, the column designed with a smaller amount of inner transverse reinforcement presented a better response than the as-built column with equal amounts of inner and outer transverse reinforcement. In addition, the widely used seismic design requirements on the volumetric ratio of transverse reinforcement seem to be conservative for the ductile design of circular hollow concrete columns.