Abstract:
Accurate assessment of the structural response of unreinforced masonry buildings when subjected to earthquake loading is essential for the design of efficient and effective seismic retrofit interventions. This study focused on determining the in-plane seismic performance of unreinforced masonry perforated shear walls in order to implement controlled rocking response as a hybrid retrofit solution. The experimental programme and the findings from a series of pseudo-static push-over tests performed on coupled unreinforced masonry pier sub-structures is presented. These sub-structures consisted of two piers with varying aspect ratio and absolute size and were subjected to different levels of vertical overburden. The walls were constructed in the common American bond formation using solid clay bricks and a 1:2:9 composition lime mortar, consistent with historical New Zealand unreinforced masonry buildings. The specimen geometries were chosen to not only replicate typical New Zealand unreinforced masonry perforated shear wall geometries but to also provide data on the three possible failure mechanisms – diagonal shear failure, sliding shear failure and rocking flexural response.When subjected to horizontal load the piers in both sub-structures exhibited a rocking response, with no diagonal shear cracking visible. The damage was concentrated in the spandrel section that spanned across the opening and this was attributed to both flexure and shear forces within the spandrel.