Shake‑table testing of a stone masonry building aggregate: overview of blind prediction study

City centres of Europe are often composed of unreinforced masonry structural aggregates, whose seismic response is challenging to predict. To advance the state of the art on the seismic response of these aggregates, the Adjacent Interacting Masonry Structures (AIMS) subproject from Horizon 2020 project Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe (SERA) provides shake-table test data of a two-unit, double-leaf stone masonry aggregate subjected to two horizontal components of dynamic excitation. A blind prediction was organized with participants from academia and industry to test modelling approaches and assumptions and to learn about the extent of uncertainty in modelling for such masonry aggregates. The participants were provided with the full set of material and geometrical data, construction details and original seismic input and asked to predict prior to the test the expected seismic response in terms of damage mechanisms, base-shear forces, and roof displacements. The modelling approaches used differ significantly in the level of detail and the modelling assumptions. This paper provides an overview of the adopted modelling approaches and their subsequent predictions. It further discusses the range of assumptions made when modelling masonry walls, floors and connections, and aims at discovering how the common solutions regarding modelling masonry in general, and masonry aggregates in particular, affect the results. The results are evaluated both in terms of damage mechanisms, base shear forces, displacements and interface openings in both directions, and then compared with the experimental results. The modelling approaches featuring Discrete Element Method (DEM) led to the best predictions in terms of displacements, while a submission using rigid block limit analysis led to the best prediction in terms of damage mechanisms. Large coefficients of variation of predicted displacements and general underestimation of displacements in comparison with experimental results, except for DEM models, highlight the need for further consensus building on suitable modelling assumptions for such masonry aggregates

Seismic assessment of URM pier spandrel systems via efficient computational modeling strategies

The final authenticated version is available online at https://doi.org/10.1007/s10518-023-01744-5.Predicting the seismic behavior of unreinforced masonry (URM) structural systems is a complex task, given various inherent sources of uncertainty associated with material properties, geometry, and boundary conditions. As the selection of computational strategies is a trade-off between prediction accuracy and computational cost, it is often challenging to find a consensus. To this end, this study presents three computational modeling strategies that can be used in the seismic analysis of URM structures. The first two approaches utilize the discrete element method (DEM) and are based on pre-defined macro-block mechanisms, whereas the third approach makes use of the computational thrust line analysis (CTLA). Such methods provide accurate predictions on the in-plane lateral load-carrying capacity of URM pier-spandrel structures with a reasonable computational cost and fewer input parameters, making them efficient compared to detailed numerical models. The results are found to be in good agreement with the experimental data on two full-scale pier-spandrel systems with either timber lintel or shallow arch above a central opening. This study also provides a detailed comparison of the applied methods and suggests multi-level use of proposed modeling strategies for better informed decision-making, starting from the most simplified method (CTLA) towards the advanced solutions as more information is collected.Peer ReviewedPostprint (author's final draft

Modelling the in-plane/out-of-plane interaction of brick and stone masonry structures using Applied Element Method

This research focuses on the numerical modelling of the seismic behaviour of unreinforced masonry (URM) structures with interconnected in-plane (IP) loaded and out-of-plane (OOP) loaded walls. The mechanical behaviour of such wall assemblies is complex and comparatively more challenging than that of isolated components, involving the interaction between interlocked orthogonal elements subjected to different load types. IP/OOP interaction phenomena are also challenging to model numerically, and their simulation is still relatively unexplored using the Applied Element Method (AEM) – the discrete simplified micro-modelling strategy employed in this paper. To fill this knowledge gap, the AEM is herein adopted to simulate the experimentally observed seismic behaviour of two URM building prototypes, one made of clay bricks and the other of stone blocks. The AEM models developed are calibrated and validated against previous experimental data, showing a satisfactory agreement between measured and numerical responses. In addition, a parametric study was performed using pushover analysis to investigate the influence of key material properties on the overall behaviour of the clay brick masonry specimen. The study suggests that the AEM models used in this study are suitable for conducting subsequent seismic assessment of URM structures with interlocked IP/OOP loaded walls, providing validated modelling strategies that can be useful to both researchers and engineering practitioners.</p

Blind predictions of shake table testing of aggregate masonry buildings

In many historical centers in Europe, stone masonry is part of building aggregates, which developed when the layout of the city or village was densified. The analysis of such building aggregates is very challenging and modelling guidelines missing. Advances in the development of analysis methods have been impeded by the lack of experimental data on the seismic response of such aggregates. The SERA project AIMS (Seismic Testing of Adjacent Interacting Masonry Structures) provides such experimental data by testing an aggregate of two buildings under two horizontal components of dynamic excitation. With the aim to advance the modelling of unreinforced masonry aggregates, a blind prediction competition is organized before the experimental campaign. Each group has been provided a complete set of construction drawings, material properties, testing sequence and the list of measurements to be reported. The applied modelling approaches span from equivalent frame models to Finite Element models using shell elements and discrete element models with solid elements. This paper compares the first entries, regarding the modelling approaches, results in terms of base shear, roof displacements, interface openings, and the failure modes