Flexural performance of concrete-encased concrete-filled steel tubes

摘要

The flexural performance of concrete-encased concrete-filled steel tubes (CFSTs) was investigated. A finite-element analysis (FEA) model is developed to analyse the flexural behaviour of the composite member and a set of test data used to verify the FEA modelling. Full-range analysis of the moment-curvature relation, the stress distributions across the composite section and the interactions between steel and concrete was carried out. It was found that thin-walled steel tubes can be used in concrete-encased CFSTs and develop full plastic strength without local buckling before reaching the ultimate state. A strut-and-tie model is proposed for the load transfer mechanism of a concrete-encased CFST member under bending. Finally, the paper presents a parametric study to derive simplified formulas for predicting the flexural capacity of concrete-encased CFST sections.