Non-compression X-bracing system using CF anchors for seismic strengthening of RC structures

Abstract

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.