Experimental and Theoretical Study of Concrete-Filled Steel Tube Columns Strengthened by FRP/Steel Strips Under Axial Compression

Abstract Concrete-filled steel tube (CFST) columns are widely used in civil engineering because of their excellent bearing capacity; however, the reinforcement CFST lacks effective measures. To strengthen quickly and effectively, two methods, namely, winding FRP (fiber reinforced polymer) or strips, were explored this work. Two unconfined columns, eight FRP-strengthened four welded strip-strengthened manufactured tested. The failure modes axial load–strain curves all specimens under compression load concluded compared. effects primary parameters, such as layers (1, 2, 3 4 layers) strip thickness (3.0 6.0 mm), on capacity deformation also investigated. ultimate increased from 28.72 to 64.16% after being confined by with one layers. column 3.0 mm strips 28.46% 49.82%, respectively, compared column. Thus, increase can markedly improve compressive behavior FRP/welded columns. cost performance different methods showed that is nearly 40% when same strengthening effect was obtained, which indicated more cost-efficient than FRP. Finally, six existing models for presented evaluated. From evaluation results, Zhang et al.’s model, Lu model Hu shown provide best applicability accuracy. Based Mander a proposed accurately predict