Experimental and Theoretical Study on Eccentric Compression of Hollow Section Concrete-Filled GFRP Tube

Existing research on hollow section concrete-filled GFRP tube (HS-CFGT) columns has largely focused on their behavior under axial compression. However, these members are often subjected to eccentric loading in practice, which remains insufficiently understood. In particular, the coupled effects of axial force and bending, as well as the influence of geometric variation, have not been adequately addressed in current studies. To address this gap, this study presents an experimental investigation of HS-CFGT columns, including both cylindrical and tapered configurations. A series of tests was carried out at different levels of eccentricity to examine load-carrying capacity, deformation behavior, and failure characteristics. The results indicate that increasing eccentricity leads to a clear reduction in load capacity and stiffness, with failure typically initiated by crushing of the inner concrete, followed by progressive rupture of the GFRP tube. In addition, lateral deformation becomes more pronounced as eccentricity increases. It is also observed that, in the present tests, tapered members exhibited slightly higher load-carrying capacity than cylindrical members at relatively low eccentricities. This observation may suggest a beneficial effect of non-uniform geometry. Based on these observations, a design-oriented prediction formulation is proposed by incorporating the interaction between axial force and bending moment. The proposed model provides a practical and reliable tool for evaluating HS-CFGT members and supports their safe application in structural systems where eccentric loading cannot be avoided.