POST-FIRE PERFORMANCE OF ELLIPTICAL CONCRETE-FILLED STEEL TUBE STUB COLUMNS

In recent years, concrete-filled steel tube (CFST) structures have been widely used in modern high-rise buildings. Compared with traditional circular and square CFST columns, elliptical concrete-filled steel tube (ECFST) columns show better structural performance such as higher torsion stiffness and flexural stiffness. The structural performance of ECFST columns at ambient temperature and in fire condition have been investigated by previous researchers. However, very limited research on the post-fire performance of ECFST columns has been conducted. In this paper, finite element analysis (FEA) models of ECFST stub columns were established to investigate their post-fire performance. In order to study the influence of section type on the post-fire performance of CFST stub columns, FEA models of circular and square CFST stub columns were also built to compare with the ECFST model. The temperature development in fire exposure stage, axial load versus average axial strain curves, load distribution and steel tube-core concrete interaction during the post-fire loading process were obtained and discussed.