Behaviors of eccentrically loaded ECC-encased CFST columns after fire exposure

Abstract

This paper intends to investigate the mechanical behaviors of eccentrically loaded engineered cementitious composite (ECC)-encased concrete filled steel tube (CFST) columns after fire exposure. Totally seven ECC-encased CFST columns and one concrete-encased CFST column were designed and tested with the consideration of different parameters, i.e., heating-up time, eccentricity ratio, stirrup spacing and longitudinal reinforcement ratio. It was found that the severe concrete spalling was noticed for concrete-encased CFST column, while the integrity of ECC-encased CFST column was well maintained under identical fire-exposed circumstances. After fire exposure for 45 min, the eccentric load carrying capacity and flexural stiffness of ECC-encased CFST column are 57.8 % and 63.5% higher than that of concrete-encased CFST column, respectively. A theoretical model was proposed to predict the residual eccentric load strength of ECC-encased CFST columns after fire exposure, and the maximum error of the calculation result was within 12 %.