Design Formulas of Concrete Filled Circular Steel Tubes Reinforced by Carbon Fiber Reinforced Plastic Sheets

Abstract

Concrete-filled steel tube structure has advantages such as excellent deformation capacity, energy absorption and fire-resistance. However, CFT column has the drawback of local buckling at steel tube due to the deterioration of confinement effect after steel tube yield. To solve the problem, CFT column system reinforced by CFRP(Carbon Fiber Sheets) will be introduced and the structural behaviors of CFRP reinforced columns will be compared with those of the current CFT columns. The main experimental parameters are diameter-thickness (D/t) and number of carbon FRP sheet layers. 10 specimens were prepared with the main experimental parameters. Axial compression test were conducted and axial behavior maximum strength capacity, and ductility capacity were analyzed between CFRP reinforced columns and the current CFT columns. To propose of design formula for FRP reinforced CFT columns, confinement effectiveness coefficient of confined concrete were proposed based on the experimental results. Finally, base on the coefficient, the axial design formula for FRP reinforced CFT columns were proposed and compared the design strength values with the experimental strength values. (C) 2011 Published by Elsevier Ltd.