A Numerical Study addressing the Stress Distribution in Circular Steel Tube Confined Concrete Columns considering Various Concrete Strengths

Abstract

The axially compressive behavior of Steel Tube Confined Concrete (STCC) columns has been experimentally investigated by many researchers throughout the world. However, it is extremely complicated to measure the stresses of steel tubes and concrete core in real tests. Therefore, to investigate the fundamental behavior of STCC columns under axial compression, this paper presents a numerical study that explores the stress distribution in steel tubes and concrete core. The circular STCC columns with the use of Normal Strength Concrete (NSC), High Strength Concrete (HSC), and Ultra-High Strength Concrete (UHSC) were simulated in a Finite Element Model (FEM) in ABAQUS. The material model for confined concrete incorporating a wide range of concrete strength values was developed in the simulation. The obtained from FEM curves of load versus strain of circular STCC columns were compared with those measured in real tests to verify the accurateness of the FEM. Deriving from the results of FEM, the stress states and their distribution in outer steel tubes and concrete core along the column height were described. Also, the longitudinal stresses on the cross-section of the concrete core were calculated corresponding with the load stage to quantify the strength enhancement of the concrete core due to the confinement effect from the steel tube. Furthermore, the confining pressure provided by the outer steel tube and impacting on the concrete core was plotted. Based on the findings in this paper, the effect of various concrete strengths on the stress distribution in circular STCC columns was investigated.