SSRG International Journal of Civil Engineering (SSRG-IJCE) – volume 3 Issue 11 – November 2016 ISSN: 2348 – 8352 www.internationaljournalssrg.org Page 1 Behaviour of Steel Concrete Composite Columns under Lateral Load R.Thirumalai 1 , S.Gobinath 2 , K.S.Deva Prasanth 3 , P.Gowtham 4 , S.Gowtham Kumar 5 1 Assistant Professor, Department of Civil Engineering, Adhiyamaan College of Engineering and Technology, Hosur- 635109, Tamilnadu,India. 3,4,5 Department of Civil Engineering, Adhiyamaan College of Engineering and Technology, Hosur- 635109,Tamilnadu,India. 2 Research Scholar, Visvesvaraya Technological University, Belagaum, Karnataka, India. Abstract- Nowadays, Composite sections of the steel and concrete have been utilized and considered around the world, yet filled tubular columns require more consideration. Broad examination work has been done in Japan in the most recent 15 years on this. This present attempt shows a trial study on the performance of Concrete Filled steel Tubular columns (CFT).The present research work depicts about signifying the utilization of Concrete Filled steel Tubular columns (CFT) instead of Reinforced Columns & to determine the conduct of composite columns. For this purpose sixteen numbers of columns with various cross area and different thickness of steel tube (8 short columns and 8 long columns) is subjected to external axial prestress and lateral loads. The circular and square composite columns are casted with different L/D apportion and wall thickness. The concrete used is M20.It is observed that Circular composite columns has less deflection and high load bearing capacity with deferred buckling while compared to the square composite columns. Keywords:- Concrete Filled steel Tubular columns,Eurocode-4,Lateral buckling, External Prestress. I. Introduction A steel-concrete composite segment is a compression member, involving either a concrete encased hot-rolled steel segment or a concrete filled tubular segment of hot- rolled steel and is for the most part utilized as a load bearing member in a structural composite frames. Typical cross-sections of composite columns with completely and halfway concrete encased steel segments are delineated in Fig. 1 indicates three typical cross-segments of concrete filled tubular segments. Note that there is no necessity to give extra reinforcing steel for composite concrete filled tubular areas, with the exception of prerequisites of fire resistance where appropriate. In a composite column both the steel and concrete would oppose the outside stacking by communicating together by bond and friction. Supplementary support in the concrete encasement averts extreme spalling of concrete both under ordinary load and fire conditions. In composite development, the exposed steel sections bolster the underlying construction loads, including the heaviness of structure amid development. Concrete is later thrown around the steel segment, or filled inside the tubular areas. The concrete and steel are joined in such a fashion, to the point that the benefits of both the materials are used viably in composite column. The lighter weight and higher quality of steel allow the utilization of smaller and lighter foundations. The ensuing concrete expansion empowers the building casing as far as possible the sway and horizontal deflections. II. Theoretical Design by EUROCODE-4 EUROCODE-4 is the most recently completed international standard in composite construction. EUROCODE-4 covers concrete - encased and partially encased steel sections and concrete-filled sections with or without reinforcement. EUROCODE-4 considers confinement effects for circular sections when relative slenderness has value less than 0.5. EUROCODE-4 uses limit state concepts to achieve the aims of serviceability and safety by applying partial safety factors to load and material properties. It is the only code that treats the effects of long-term loading separately. The ultimate axial force of a circular column is, PP = Aa* η 2 ϸa + Ac * ϸCk * 1 + η 1* { t / d } * { fy / fck } Where, η 1 = η 10 [ 1 – {10e /d}. η 2 = η 20 + { 1 - η 20 } * {10e / d}. ϸa = { fy / ϒa }. ϸCk = { fck / ϒc }. PP – plastic resistance of columns. Aa & Ac - Area of the steel and concrete (mm 2 ).