Experimental and numerical investigations of post-fire behaviour of circular steel tube confined steel-reinforced concrete columns under eccentric loading

Experimental and numerical analysis were conducted to investigate the post-fire behaviour of circular steel tube confined steel reinforced concrete (STCSRC) columns. A total of fifteen circular STCSRC columns, including five stub specimens and ten slender specimens, were tested under eccentric loading after heating following the ISO-834 standard fire curve. The test findings, such as cross-sectional temperature, failure modes, column deformation, residual load-bearing capacity, strains of steel tubes, etc., were all discussed in detail. A sequential thermal-stress coupling finite element (FE) model, including a heat transfer FE model and a mechanical FE model, was then developed using ABAQUS software and verified using the test results. To obtain further numerical data over a wide range of parameters, a parametric analysis was carried out using the established FE models. A simplified calculation method was presented to estimate the residual load-bearing capability of circular STCSRC columns subjected to eccentrical compression after ISO-834 fire exposure.