Repair of concrete-filled FRP tube columns with damaged tubes

Abstract

The effectiveness of repairing damaged Concrete-Filled Fiber Reinforced Polymer (FRP) Tube (CFFT) axial members is studied. The damage was introduced in the form of linear cuts through the full tube thickness. The effectiveness of adhesively-bonded FRP patches that may or may not include mechanical fasteners is investigated. The study varied the cut angle, the bond length of the patch, the fiber type being glass or carbon, the number and pattern of mechanical fasteners, the patch extension beyond cut tips, and compared wet layup glass-FRP (GFRP) patches to prefabricated GFRP shells cut from a similar tube. It was shown that the vertical cut reduced axial compressive strength significantly. As the bond length of the GFRP repair patch increased the axial strength recovery increased, but not fully. When the ends of the GFRP patch were overlapped, a full strength recovery was achieved. The prefabricated GFRP shell patch (cut from similar tube) provided the highest strength recovery, compared to FRP wet layup. Adding mechanical fasteners enhanced strength recovery further, to a certain point. A simple empirical design model is proposed and a design example is presented.