Experimental Study of the Behavior of Composite Columns

F. Nateghi-A., T. Moradi Shaghaghi

 

Abstract
Composite columns have been used in constructions for many years due to their advantages over ordinary columns. Concrete filled steel tubes, CFST are one such column. Some of the advantages of these types of columns are known as; not needing molding, high ductility, relative high resistance with low volume properties, low deformation capability relative to ordinary steel columns and most commonly economical potential. In these columns, development of full load bearing capacity depends on bond strength between steel and concrete, local buckling of steel encasing, ratio of side dimension of the columns to steel thickness (D/t) , length to dimension ratio (L/D) and finally the shape section column. Due to these enormous potentials, a general research program was launched to investigate CFST’s in experimental manner. This program was planned and done at IIEES structural lab in Tehran, Iran. In order to achieve the goals of the project, seventeen specimens were constructed using a 1:3 scale and were tested as cantilever columns. Five specimens loaded axially and twelve Specimens were loaded under a constant axial load while laterally loading under an enhancing Lateral cyclic load based on a displacement controlled condition. Three distinct geometrical shapes namely, square; circle and octagonal sections were considered and tested. Specimens were also tested using stiffeners in comparison to specimens without stiffeners. This paper presents the results obtained and ways and methods of achieving the goals of the project. Using of stiffeners inside steel tube in critical zone, significantly improves column behavior and its ductility.

 

Keywords:

Concrete filled steel tube columns, Steel tube, Lateral cyclic Load, Steel stiffener, Ductility, Hysteric Behavior