Hollow Concrete Columns (HCCs) are one of the preferred construction systems in civil infrastructures including
bridge piers, ground piles, and utility poles to minimize the overall weight and costs. HCCs are also considered a solution to
increase the strength to mass ratio of structures. However, HCCs are subjected to brittle failure behaviour by concrete crushing
means that the displacement capacity and the strength after steel yielding in HCCs are decreasing due to the unconfined
concrete core.