A forming tube for forming and reinforcing a concrete column includes a tubular lining and a fiber-reinforced composite shell. The tubular lining is made from a first material, and has inner and outer tubular surfaces. The inner tubular surface has a plurality of ridge units displaced from one another in a direction of an axis. Each ridge unit has a plurality of ridges displaced from one another in a circumferential direction. The fiber-reinforced composite shell is made from a second material different from the first material, and is configured to enclose the outer tubular surface. The fiber-reinforced composite shell is formed by winding a prepreg filament on the outer tubular surface, followed by curing the prepreg filament.