Abstract
CFT columns have many advantages such as increasing the compressive strength and ultimate strain of concrete, and aslo increasing the buckling load of steel tube. The purpose of this paper is evaluation of present design code formulas for high strength steel composite members and validity of width-to-thickness ratio limit especially in 800 MPa grade steel. Total 8 short column specimens which were made by high strength steel were tested. Main test variables were width-to-thickness ratio and concrete compressive strength. Test results were analyzed in the viewpoint of axial load capacity, load-shortening relationship, and failure mode. Test results indicated that axial load capacity in all specimens exceeded over 20% compared with the calculated value by KBC2009, and over 30% by the AISC 360-10 regardless of the width-to-thickness. And local buckling was not observed before the strain was reached the yield strain of steel in compact, non-compact and slender width-to-thickness ratio specimens by AISC 360-10 regulations. From these test results, we can concluded that the limit of width-to-thickness ratio in present design code can be modified in high strength steel composite members.
