Experimental investigation of fire-exposed steel tubular stub columns wrapped with CFRP sheets

Abstract

This paper investigates the effect of high temperature (600 °C, 800 °C, 1000 °C and 1100 °C) and the layers of carbon fibre reinforced plastics (CFRP) sheets (one, two, three, four) on the behaviour of fire-exposed steel tubular stub columns. Forty specimens were tested to investigate the failure modes, ultimate bearing capacity under axial compression, load-strain relationship, load-displacement relationship and initial stiffness of the specimens. Ultimate bearing capacity and initial stiffness decrease with the increase of temperature. The ultimate bearing capacity and ductility of fire-exposed specimens wrapped with CFRP sheets increase with the increase of CFRP sheets layers. After being strengthened by CFRP sheets with the same number of winding layers, circular steel tubular (CST) stub columns obtained a greater load-bearing capacity increase than square steel tubular (SST) stub columns. The largest enhancement of the ultimate bearing capacity of fire-exposed specimens is 59.47%. A recommended formula for the calculation of ultimate bearing capacity of fire-exposed specimens wrapped with CFRP sheets is proposed.