2D meso-scale modeling of masonry elements using cohesive elements

Many stone masonry structures that were constructed in the past centuries are now counted towards the cultural heritage. The low strength and brittle behavior make these heterogeneous structures very vulnerable to various natural or man-made disasters such as earthquakes. In order to ensure their structural safety and to implement appropriate interventions, engineers need to understand the failure mechanism and to estimate the force and deformation capacity. Since it is difficult to obtain detailed material properties and simulate strong discontinuities, advanced simulation techniques have only been applied recently to masonry structures. In this paper, we simulate stones and mortar separately on a meso level and use cohesive zone modeling for simulating dynamic crack propagation. With this approach, cracks are modelled explicitly and the properties of the crack interface can be easily reflected. We apply the extrinsic cohesive zone model developed by Snozzi and Molinari, 2013. In the extrinsic method, the cohesive element will not be inserted until the stress on the corresponding element edge meets a certain criterion. The finite element analysis is developed using the open source software Akantu, newly developed by LSMS, EPFL. The available cohesive element is enhanced to consider the transfer of friction across interfaces and the added code is parallelized to make use of the high performance computing capacities of Akantu. We conduct parametric studies to investigate the influence of several variables on the force-deformation characteristics of stone masonry (e.g., strength ratio between mortar and interface, the friction coefficient). The influence of the randomness of the material properties on the masonry mechanical behavior is also examined and the effect of different assumptions with regard to the correlation of variables explored