Francisco Galvez1, Luigi Sorrentino2, Jason M. Ingham1, Dmytro Dizhur1
1)  Dept. of Civil and Environmental Engineering, University of Auckland, Auckland (New Zealand)
e-mail: {fglv390,ddiz001},
2)  Dept. of Structural and Geotechnical Engineering, Sapienza University of Rome, Rome (Italy)

Keywords: Distinct Element Method; Unreinforced Masonry; Guidelines; Out-of-plane Capacity; Failure Mechanisms; Brick Bond Pattern

Abstract. Post-earthquake inspections have highlighted that out-of-plane failure of unreinforced masonry (URM) walls is one of the most life threatening hazards related to earthquakes. Connections between structural elements and interlocking across the wall section play an important role in the capacity of a URM building to withstand earthquakes. Consequently, the seismic assessment of existing URM buildings requires an appropriate methodology to correctly estimate the performance of the investigated element. International standards and guidelines for seismic assessment are often based on simplified methodologies that incorporate assumptions regarding the collapse mechanism and general behaviour of the wall. Alternatively, the Discrete Element Method (DEM) is an advanced modelling technique that can accurately predict and simulate wall behaviour without any prior assumption about the failure mechanism. Different codes capacity predictions and DEM simulations were compared to the test results of a solid two-leaf wall. The DEM proved reasonably accurate and was used to simulate one-way bending of walls with a variation of unit bond patterns and wall thickness dimensions that escape code formulations. Solid rigid elements were used to represent the distinct clay brick units and an inelastic law was assigned to the contact surfaces to simulate the mortar joints. Pushover and non-linear time history analyses were conducted and the resultant capacity curves and collapse mechanisms of each analysis were compared.