Wall size effect on the seismic response of unreinforced hollow clay brick masonry walls

The database of tests conducted in masonry walls shows that shearcompression tests are performed using a wide range of wall heights from under 1.0 m to 3.0 m. The results of these tests indicate that shorter walls tend to reach larger drift capacities; however, there is no systematic study investigating size effects within a single experimental campaign. Moreover, most walls tested on a reduced scale tend to only decrease the overall size of the wall but keep the size of the brick due to the difficulty of manufacturing scaled bricks. This document presents an experimental study of the size effect on the drift capacity of unreinforced masonry walls built with hollow clay bricks and standard cement mortar. A total number of six quasi-static cyclic tests have been conducted for three different wall sizes (heights of 2.8 m, 2.0 m and 1.4 m) and two different levels of compression load (axial load ratios of 0.10 and 0.20). All the walls had the same aspect ratio (L/H) of 0.75 and were tested under double bending boundary conditions to observe a shear-controlled behaviour. This work analyses the mechanical phenomena on the different wall sizes and the consequences observed in the seismic behaviour. Particularly, this study focuses on the influence of the wall size on the drift capacity and how the crack pattern and crack opening play a role in this behaviour. Furthermore, this research also provides a reference for how small test specimens can be for obtaining drift capacity values in storey-high walls.