Cross-bracing (X-bracing) is one of the most popular methods of seismic retrofitting. Research results indicate that X-bracing significantly increases structural stiffness and enhances the strength of the structures. However, researchers have also noted that conventional steel X-bracing methods can involve brittle failure at the connection between the brace and the building, as well as buckling failure of the braces. The current research thus investigated the structural properties of a new type of non-compression carbon fibre (CF) X-bracing system with the goal of overcoming the brittle and buckling failures that can occur with conventional steel X-bracing methods. The proposed non-compression X-bracing system uses CF bracing and anchors to replace the conventional steel bracing and bolt connection. This paper reports on the seismic resistance of a reinforced concrete frame strengthened using CF X-bracing. Cyclic loading tests were carried out, and the structural stiffness and ductility were investigated along with the hysteresis of the lateral load-drift relations. CF is less rigid than the conventional materials used for seismic retrofitting, resulting in some significant advantages: the strength of the structure increased markedly with the use of CF X-bracing and no buckling failure of the bracing was observed. NotationD depth of column f c concrete compressive strength h o clear height of column K secant stiffness between yield and zero points (V y /ä y ) M u ultimate flexural strength N axial force R strength ratio, defined as V max /V y V max maximum shear strength V mu shear force at point of ultimate flexural failure V su ultimate shear strength V u ultimate lateral load-carrying capacity V y yield shear strength ä max displacement at the maximum point ä y displacement at the yield point ì ductility ratio, defined as the maximum displacement divided by yield displacement (ä max /ä y ) r f tensile reinforcement ratio (%) r s shear reinforcement ratio (%)

Cross-bracing (X-bracing) is one of the most popular methods of seismic retrofitting, and has been shown to significantly increase the structural stiffness and strength of buildings. Conventional steel X-bracing methods typically exhibit brittle failure at the connection between the brace and the building, or buckling failure of the braces. This study investigated the structural properties of a new type of non-compression X-bracing system using carbon fiber composite cable (CFCC). This non-compression X-bracing system uses CFCC bracing and bolt connections between structural members and the terminal fixer of the CFCC, instead of conventional steel bracing. The aim is to overcome the brittle and buckling failures that can occur at the connection and bracings with conventional steel X-bracing methods. We carried out cyclic loading tests, and the maximum load carrying capacity and deformation were investigated, as well as hysteresis in the lateral load-drift relations. The test results revealed that the CFCC X-bracing system installed in reinforced concrete frames enhanced the strength markedly, and buckling failure of the bracing was not observed.