The failure mechanism and maximum collapse load of masonry structures may change significantly under static and dynamic excitations depending on their internal arrangement and material properties. Hence, it is important to understand correctly the nonlinear behavior of masonry structures in order to adequately assess their safety and propose efficient strengthening measures, especially for historical constructions. The discrete element method (DEM) can play an important role in these studies. This paper discusses possible collapse mechanisms and provides a set of parametric analyses by considering the influence of material properties and cross section morphologies on the out of plane strength of masonry walls. Detailed modeling of masonry structures may affect their mechanical strength and displacement capacity. In particular, the structural behavior of stacked and rubble masonry walls, portal frames, simple combinations of masonry piers and arches, and a real structure is discussed using DEM. It is further demonstrated that this structural analysis tool allows obtaining excellent results in the description of the nonlinear behavior of masonry structures.

In this paper, a simple discontinuous upper bound limit analysis approach with sequential linear programming mesh adaptation is presented. Rigid, infinitely strong triangular elements with both linear and Bezier curved edges are considered. A possible jump of velocities is allowed at the interfaces between contiguous elements, thus allowing plastic dissipation on curved interfaces. Bezier curved edges are used with the sole aim of improving the element performance when dealing with limit analysis problems involving curved sliding lines. The model performs poorly for unstructured meshes (i.e. at the initial iteration), being unable to reproduce the typical plastic deformation concentration on inclined slip lines. Therefore, an iterative mesh adaptation based on sequential linear programming is proposed. A simple linearization of the non-linear constraints is performed, allowing to treat the non-linear programming (NLP) problem with consolidated linear programming (LP) routines. The c..

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Masonry structures constitute a large portion of the built heritage around the world, from the past and still today. Therefore, understanding their structural behavior is crucial for preserving the historical characteristics of many of those buildings and in addressing the requirements for housing and sustainable development. Due to its composite and highly non-linear nature, the analysis of masonry structures has been a challenge for engineers. This paper presents a set of advanced models for the mechanical study of masonry, including the usual micro-modeling approaches (in which masonry constituents, i.e. unit and joint, are represented separately), macro-modeling (in which masonry constituents are smeared in a homogeneous composite) and multi-scale techniques (in which upscaling from micro to macro is adopted). An extensive overview of its computational features is provided.Finally, the engineering application of such strategies is presented and covers problems from the masonry components level (meso-scale) to the structural element itself, and ultimately to the level of monumental buildings (super-large). The structural safety assessment and/or strengthening schemes evaluation are performed amid the static, slow dynamics or earthquakes, and fast dynamics or impact and blast ranges.

The present work entails a statistical analysis of the data collected for 112 churches in the affected region, including in situ damage observed by the authors and the structural assessment classification assigned by local authorities. The seismic performance of these churches is discussed and compared with both the structural classifications used in Italy, where a specific survey form for churches is used, and with the building damage classifications assigned by the local authorities.