Effects of debonding on circular CFST stub columns

Core concrete subjected to confinement effect from steel tube is the main advantage of concrete filled steel tubular (CFST) column under compression. However, this beneficial composite action could be weakened even destroyed by debonding, which is almost unavoidable as a common phenomenon in CFST structures and has not been considered satisfactorily by current design codes. In this paper, the influence of debonding on circular CFST stub columns was investigated experimentally and numerically. The main experimental parameters were the debonding arc-length ratio, the confinement factor and the load mode. Meanwhile, the finite element models were implemented using the ABAQUS finite element software, of which the validity and accuracy were verified by test results. Utilising the finite element model, the parametric analysis was carried out to study the influence of the following parameters on the ultimate load capacity of debonding specimens: debonding arc-length ratio, debonding thickness and confinement factor. Based on the results of parametric analysis, a simplified calculation formula was proposed to calculate the ultimate load capacity of circular CFST stub columns with debonding. © 2011 Elsevier Ltd. All rights reserved.