Effect of Geometric Discontinuities on Strains in FRP-Wrapped Columns

Extensive research on fiber-reinforced polymer (FRP) confinement strengthening for concrete columns has led to a good understanding of, and accurate models for, circular columns subjected to axial load. This research is being extended to noncircular and eccentrically loaded columns, steel tubular, and concrete-filled steel tubular columns. A significant gap in our understanding of all these columns, however, is that the apparent FRP strain at failure is significantly lower than the ultimate strain in a flat coupon test. There may be many factors contributing to this complex phenomenon. This paper shows that one of these factors is the geometrical discontinuities at the ends of the FRP wrap. The significance of the effect of discontinuities on the strain concentrations in the FRP wrap and the bonding adhesive is explored through an elastic finite-element analysis.