Abstract: In composite construction the initial construction loads including the self-weight of the structure are supported by the bare steel sections. Later concrete is casted around or filled inside the steel section. The steel and concrete are combined in such a way that advantages of both the materials are effectively utilized. Higher strength and lighter weight enables the use of steel in smaller and lighter foundations. The subsequent concrete addition enables the building frame to limit the sway and lateral deflections. The objective of this study is to optimize the reinforcement in circular columns based on buckling. In this study the buckling behaviour of a circular column under axial load is examined. A loading platform is created and a concentrated axial load is applied to a conventional circular column so as to measure the buckling. Later same procedure follows with another sample of column in which reinforcement bars are replaced by a hollow GI pipe. Buckling is measured under the same axial load and these values are compared with the conventional method. Experiment is repeated by adding steel fibres for better results.

Keywords: Composite columns, Buckling, Conventional column, New material model, Hollow GI pipe, Stel fibres.