Experimental investigation on reinforced concrete interior beam-column joints rehabilitated by ferrocement jackets

In this study, a method for rehabilitating reinforced concrete interior beam-column joints using ferrocement jackets with embedded diagonal reinforcements is proposed. It improves seismic performance of substandard beam-column joints and repairs deteriorated concrete cover without increasing the dimensions of the joints. Ferrocement, comprising mortar and wire mesh, was applied to replace concrete cover to enhance shear strength of the joints. Diagonal reinforcements were installed to reduce the forces transferred to the joint core. Four 2/3 scale interior beam-column joints, including one control specimen and three strengthened specimens, were prepared and tested under quasi-static cyclic loading. Three types of mortars were considered for each strengthened specimen. Test results have indicated that the proposed rehabilitation method can improve seismic performance of interior beam-column joints using ferrocement with high strength mortar. Strength of mortar is the vital factor affecting the performance of strengthened specimens. Anchor bolts installed at the interface between ferrocement and concrete substrate improve bonding and overall performance. Finally, a method for predicting the shear strength of joints rehabilitated by ferrocement jackets with embedded diagonal reinforcements is proposed.