Unreinforced clay brick masonry wallettes sheared perpendicular or parallel to bed joints—A comparative study

The analysis of unreinforced masonry shear walls should base on values of proper determined main mechanical properties of masonry. There are two main types of shear loading directions: perpendicular to the bed joints—corresponding to shear walls in buildings subjected to irregular vertical deformations (e.g. irregular settlement), and parallel to bed joints—corresponding to shear walls against wind action. To explain the behaviour and shear strength as well as in-plane deformability of unreinforced clay brick masonry subjected to shearing in both orthogonal directions the experimental investigation was carried out at the Faculty of Civil Engineering of the SUT. Small masonry wallettes were subjected to shearing in direction perpendicular (vertical shearing) or parallel (horizontal shearing), with and without vertical precompression. All tests were based on not standardised method and specially constructed test stands. In total were tested eight series of small wallettes: six series of specimens sheared in direction perpendicular to the bed joints and two series of similar wallettes sheared in direction parallel to the bed joints. All tested specimens were made of clay solid bricks strength class “15” and the most popular cement-lime mortar M5 (1: 1: 6) using English bond of masonry units. The wallettes had similar rectangular shape. The dimensions of specimens subjected to vertical shearing were 1.29 m × 1.415 × 0.25 m and subjected to horizontal shearing 1.68 m × 1.415 × 0.25 m. All specimens were loaded in one cycle. The comparison of behaviour and failure process (modes of failure) for both loading directions does not show any meaningful differences. However, the values of shear stresses and corresponded to them shear strains determined for the state of cracking in case of wallettes sheared vertically with different levels of precompression were higher than obtained for specimen sheared horizontally. The values of shear stresses for both directions were compared with, based on the Coulomb-Mohr criterion, relationship for fvk calculation, given in Eurocode 6. The possibility of using of this relationship in analysis of shear walls also subjected to vertical shearing was confirmed.