Axially Loaded Reinforced Concrete Columns with a Square Section Partially Confined by Light GFRP Straps

Abstract

The study presents the experimental behavior of reinforced concrete columns strengthened externally by transverse glass fiber-reinforced polymer (GFRP) sheets. The columns had a square section and very low concrete strength. The internal steel reinforcement comprised sparse stirrups and longitudinal bars with two different qualities, S220 or B500C. The specimens were lightly confined by full wraps or partial GFRP straps. The straps were placed in between the existing steel stirrups. Three different widths of GFRP straps were examined. A series of plain concrete columns with identical GFRP strengthening was designed in order to assess the partial wrapping effects and compare them with reinforced concrete columns. The columns were subjected to axial compressive monotonic load up to failure. The achieved strength and ductility levels of the strengthened columns suggest that partial wrapping can efficiently upgrade the mechanical behavior of columns with a square section. Fully or partially GFRP wrapped columns with S220 slender bars require relatively higher GFRP strengthening than their counterparts with B500C columns to achieve similar ultimate strains.