Study on concrete-filled fluted steel tube columns

Abstract

Concrete-Filled Steel Tube (CFST) columns combine the advantages of ductility, generally associated with steel structures, with the stiffness of a concrete structural system. Compared with the hollow steel tube columns, local buckling in the CFST columns is delayed due to the presence of concrete infill. Adding flutes to the columns can increase their moment of inertia and thus increasing the load resistance of the column. This paper presents the analytical and theoretical results of the study on behaviour of CFST columns with rectangular flutes. Normal grade concrete without reinforcement is used as in-fill. Number, position, and size of flutes are varied to understand the performance of flutes in structural strength enhancement of Concrete-Filled Rectangular Fluted Steel Tube Columns (CFRFST). Providing flutes is found to be beneficial and outward fluted columns are better than inward fluted columns. Four numbers of rectangular flutes provided outwardly of width D/3 and depth D/10 where D is the diameter of the CFRFST Column is found to be the most optimum cross-section of CFRFST columns considering the load carrying capacity and practical applications. Eurocode-4 is followed to generate non-dimensional P-M interaction curves for CFRFST columns with different steel contribution factors.