Seismic testing of repaired unreinforced masonry building having flexible diaphragm

The in-plane rocking behavior of unreinforced masonry walls is generally perceived as a stable desirable behavior. However, there may be instances where the available lateral resistance of such walls would be inadequate. In that perspective, fiberglass strips were applied to damaged unreinforced masonry (URM) shear walls to increase their in-plane lateral load-resisting capacity. This paper reports on the dynamic response and behavior of a full-scale one-story unreinforced brick masonry building specimen having a flexible wood floor diaphragm. The shear walls were damaged in a previous test and repaired with fiberglass strips. The results demonstrate the effectiveness of fiberglass strips in enhancing the in-plane seismic response of URM walls failing in rocking and bed joint sliding mode. The response of the wood diaphragm and its interaction with the shear walls have also been studied. As a consequence of the increased in-plane lateral resistance of URM shear wall, the diaphragm was subjected to larger deformations in the inelastic range. The evaluation of experimental results and the comparison with the existing procedures have revealed that the diaphragm deflections observed experimentally closely matched those predicted using the Federal Emergency Management Agency 356 and Agbabian, Barnes, and Kariotis models.