Ductile Anchorage for Connecting FRP Strengthening of Under-Reinforced Masonry Buildings

Fiber-reinforced polymer (FRP) composites have been examined as a convenient and cost-effective means of strengthening unreinforced masonry structures. Seismic design in the United States is almost entirely based on the assumption that the structural system provides a ductile failure mode. FRP strengthened masonry walls inherently have brittle failure modes due to the nature of the strengthening system. The concept explored in this article is the introduction of ductility using a hybrid strengthening system. This involves the placement of structural steel or reinforcing steel at critical locations in the lateral force resisting system. This article presents the testing and analysis of a ductile structural steel connection that can be used to strengthen the connection of FRP strengthened shear walls to the foundation. The connection also increases energy dissipation. Results indicate that a ductile failure mode can be attained when the connection is designed to yield prior to the failure of the FRP strengthening.