RESEARCH ON BIAXIAL BENDING PERFORMANCE OF STEEL FIBER REINFORCED CONCRETE COLUMNS CONFINED BY CARBON FIBER POLYMER BARS

To investigate the effect of carbon fiber reinforced polymer (CFRP) reinforcement on the mechanical behavior of reinforced concrete columns, compression and bending performance tests were conducted on CFRP confined plain concrete columns and steel fiber reinforced concrete slender columns under biaxial bending loads. The effects of steel fiber content, number of CFRP layers, and load eccentricity on the bending characteristics of column specimens were investigated. The experimental results show that compared with the reference group (without CFRP), the hoop effect of CFRP significantly improves the strength, ductility, and deformation resistance of reinforced concrete columns. At the same time, a numerical calculation method suitable for CFRP constrained reinforced concrete slender columns under axial load and bidirectional bending was proposed. This method introduces a double-line constitutive model for constrained concrete and stress-strain models for steel bars and CFRP to predict the structural performance of CFRP constrained reinforced concrete columns. Both in terms of load deflection curve and ultimate bearing capacity, the calculated results are in good agreement with the measured values.