Experimental and numerical investigations of the compressive behavior of concrete filled steel tubes (CFSTs)

This paper presents an experimental study to investigate the compressive behavior of circular concrete filled steel tubes (CFSTs) when subjected to pure axial loading at a low rate of 0.6 kN/s. CFSTs of three different diameter-to-thickness (D/t) ratios of 54, 32, and 20 are considered in this study filled with two concrete's compressive strengths of 44 MPa and 60 MPa. The measured compressive axial capacities are compared to their corresponding theoretical values predicted by four different international codes and standards: the American Institute of Steel Construction (AISC), the American Concrete Institute (ACI 318), the Australian Standard (AS), and Eurocode 4. Result comparisons also included some suggested equations found in the literature. It was found that the effect of (D/t) ratio on the compressive behavior of the CFST specimens is greater than the effect of the other factors. The underestimation of the axial capacities calculated by most of these codes reduces as the pit ratio increases as verified by the experimental results. A nonlinear finite element (FE) numerical model using the commercial software package ABAQUS is also developed and verified using the presented experimental results. (C) 2012 Elsevier Ltd. All rights reserved.