Fundamental study on CFRP strengthening method for bolted connections with U-shaped carbon tow

Although bearing connections are used in spatial structures and transmission towers, improving loadcarrying capacity and/or strengthening it against earthquakes and external service loads are often difficult. While bolt strength can be enhanced using high-tension bolts, there is currently no effective method to address issues such as end failure and bearing stress fracture in bearing bolt connections. In addition, strengthening by adding steel plates increases the weight of the building, among other problems. To solve this problem, we propose a carbon tow application that prevents rupture before the bolts fail in shear. Large tow and epoxy resin were used to manufacture the specimens. The experiments showed that the shear strength of the specimens with strengthening was higher than those without strengthening. Moreover, the bolt holes expanded by approximately 35% in the experiment without strengthening, but the deformation significantly decreased with the strengthening of the carbon tow, confirming the strengthening effect.