Development of strengthening methods using angles as shear-keys

In seismic retrofitting of existing R/C buildings, indirect connection by post-installed anchors is used for the load transfer mechanism between existing building frames and steel braces or extension R/C walls. A new seismic strengthening method was developed using angles as shearkeys. In the indirect connection between the structural frame of existing buildings and earthquake resistance elements, shear force is carried by angles as shear-keys. Seismic performance of the frame strengthened by angles as shear-keys in the indirect connection was investigated experimentally. Based on the experimental results, the developed method was verified to be efficient for strengthening existing building frames.