Non-linear analysis of CFRP-wrapped steel box sections under biaxial load

The effect of biaxial compressive loading on hollow steel box column (HSBC) and concrete-filled steel box column (CFSBC) sections wrapped with low-modulus carbon-fibre-reinforced polymer (CFRP) was studied. The CFSBC and HSBC sections were simulated using Abaqus finite-element software and validated using available experimental data. Biaxial compressive loading was considered for different eccentricities (i.e. eccentricity to depth ratio (e/D) ratio of zero to 0.32). The results indicated that, for CFRP-wrapped HSBCs at low eccentricity (e/D = 0.08), compact and non-compact sections were effective at carrying higher load, while a slender section was effective for concentric loads. For the CFRP-wrapped CFSBCs, compact and non-compact sections were effective for all the eccentric loads (e/D = 0–0.32). It was also found that the low-modulus CFRP layer wrapping the CFSBC sections had no significant effect on strength. An empirical relationship was developed based on trend analysis, which gives the load-carrying capacity of any section. For the CFSBC sections, axial compression–uniaxial moment (P–M) interaction curves are presented to validate the simulation results under biaxial loading.