Experimental Behavior of High-Strength Square Concrete-Filled Steel Tube Columns under Various Load Application

Abstract

An experimental result of high-strength square concrete-filled tube columns and high-strength concrete columns subjected to axial load are presented in this paper. The dimension of square columns have the cross section of 150x150 mm and the length of 300 mm. The variables used in this observation are the wall thickness of steel tubes, which are 3.0 mm, 4.5 mm and 6.0 mm. A total of 20 specimens are tested to investigate the effects of three conditions to apply load to the column. The load is applied concentrically to the entire section, to the concrete section and to the steel tube section. From the test, it is found that the ultimate compressive strength and ductility of the high-strength concrete-filled tube columns are increased significantly compared to the reference columns. The results of these tests showed that the response curves of the high-strength concrete-filled tube columns have a linear elastic behavior up to approximately 60-80% of their maximum compressive load. Then, the behavior of the columns is nonlinear. The nonlinear behavior of the column can be classified into 2 types: Elastic-Perfectly Plastic (EPP) and Strain-Softening (SS), depending mainly on the studied variables.