Experimental study on seismic behavior of damaged unreinforced masonry walls retrofitted by vertical concrete ties and bed rebar with and without shotcrete

The present article describes experimental procedures to investigate the seismic retrofitting techniques used for damaged unreinforced masonry (URM) walls. In total, three tests were performed on a full-scale wall under constant vertical load, along with lateral loading according to the loading protocol. The unreinforced wall was tested as a reference sample. Then, the damaged sample was retrofitted with two vertical concrete ties and bed rebar on one side and retested. Finally, the damaged sample was strengthened with shotcrete on two sides and tested. The experimental results showed that strengthening the damaged unreinforced wall with the vertical concrete ties and bed rebar not only restored most of the original seismic characteristics of the wall but also significantly improved the seismic behavior of the wall. Moreover, improving seismic characteristics, the retrofitting by vertical concrete ties, bed rebar, and two-side shotcrete increased wall energy absorption capacity.