THE EFFECTS OF CONFINEMENT AND STRAIN HARDENING ON THE PERFORMANCE AND DESIGN OF SHORT CIRCULAR COLUMNS Sema NOYAN ALACALI 1 , Bilge DORAN 2 1 Ph.D. Assistant Professor of Civil Engineering, Faculty of Civil Engineering, Yıldız Technical Univ., Main Campus, 80750 Yıldız/ISTANBUL/TURKEY, Phone: (+90212) 259 70 70/2257. e.mail:[email protected]. 2 Ph.D. Lect.Dr. of Civil Engineering, Faculty of Civil Engineering, Yıldız Technical Univ.,Main Campus, 80750 Yıldız/ISTANBUL/TURKEY, Phone: (+90212) 259 70 70/2257. e.mail:[email protected]. 1