Compressive behaviours of circular concrete-filled steel tubes exposed to low-temperature environment

Abstract

This paper mainly focused on the behaviours of circular concrete-filled steel tubular (CFST) stub columns (CCFST-SCs) subjected to axial compression at different cold-region low temperatures. A test-program consisting of 14 CCFST-SCs was firstly carried out at four low temperature levels, i.e., 20, −30, −60, and −80 °C. The investigated parameters included low temperature levels and wall thickness of tube in CCFST-SC. These test results reported that under compression the CCFST-SC at low temperatures failed in shear mode, concrete crushing, outward local buckling and tensile fracture in steel tube. The axial compressive load versus shortening behaviour was reported. This paper discussed and analysed influences of different parameters on compressive behaviour of CCFST-SCs. This paper also developed theoretical models to describe the axial shortening versus compressive load behaviour of CCFST-SCs at low temperatures. Moreover, different modified code equations were proposed for determinations of ultimate compressive resistances of CCFST-SCs at low temperatures. Finally, the accuracies of these theoretical models and modified code equations were confirmed by the validations of their predictions against 25 test results. Conclusions were also given at the end based on these tests and analysis results.