Experimental study on the ultimate bearing capacity of long basalt fiber-reinforced concrete (BFRC)-filled steel tube columns under axial compression

Abstract

The strength and ductility of core concrete are important factors influencing the bearing capacity of concrete-filled steel tube (CFST) structures, and an appropriate mixing amount of basalt fiber can change the toughness index of concrete. To examine the reinforcing effect of basalt fiber on the bearing capacity of long CFST columns, axial compression bearing capacity experiments were conducted on 15 long basalt fiber-reinforced concrete (BFRC)-filled steel tube columns and 9 long CFST columns to determine the ultimate bearing capacity, load-displacement curve, and load-strain curve of the experimental columns. A comparative analysis was then performed on the experimental results and experimental characteristics of the bearing capacity to differentiate long fiber CFST columns from long CFST columns. Results revealed that compared with CFST columns, BFRC-filled steel tube columns displayed improved ultimate bearing capacities under experimental level. Specifically, for core concrete added with 12 mm basalt fiber, the ultimate bearing capacities of BFRC-filled steel tube columns with wall thicknesses of 4, 5, and 6 mm were improved by 9.7%, 8.6%, and 7.3%, respectively. For core concrete filled with 24 mm basalt fiber, the ultimate bearing capacities of long BFRC-filled steel tube columns with wall thicknesses of 4, 5, and 6 mm were improved by 7.8%, 5.7%, and 3.1%, respectively. Thus, basalt fiber improves the ductility of CFST columns. The findings of this paper is of important engineering indicate the promising application value of basalt fiber in long CFST columns.