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Comparative analysis between continuous and discontinuous methods for the assessment of a cultural heritage structure
Get PDFIn an era marked by the urgent need to ensure the safety of existing buildings according to current standards, evaluating the stability of masonry structures against hazard events has become a significant challenge. Despite the versatility and durability of masonry, structural assessments are hampered by factors such as limited information on material properties, irregular geometries, and ageing. To address this issue, numerous modelling techniques have been developed, supported by extensive scientific literature. However, significant factors related to the case study replication, such as the geometric complexity, the mechanical behaviour of masonry, the loading applications, contribute to the challenges associated with modelling procedures, including computational time, discretization procedures, and step incrementation. This paper critically discusses the most innovative modelling approaches. Specifically, it aims to compare the efficiency of the Distinct Element (discontinuous) Methods and the Finite Element (continuous) Method, both applied to the numerical simulation of a case study structure severely damaged by the 2016 Central Italy earthquake under lateral loading conditions. The continuous method is analysed using Midas FEA NX©, while the discontinuous methods are studied using 3DEC© and LMGC90© software, each with different contact conditions. Finally, the investigation highlights the main advantages and disadvantages of each method. In particular, the discontinuous method demonstrates reliability in accurately replicating failure patterns, whereas the continuous method allows for a faster model setup, making it suitable for preliminary studies on structural dynamics
Mechanisms detection by nonlinear finite and distinct element simulations of a historical religious masonry complex
No full textThe detection of collapse mechanisms in masonry structures poses a critical challenge in structural engineering, particularly when dealing with complex historical buildings under seismic loading. Masonry structures exhibit highly non-linear mechanical behaviour due to their composite nature, characterized by discontinuities, weak tensile strength, and anisotropy. Accurately capturing these failure mechanisms, which include cracking, crushing, and sliding along joints, is essential for evaluating their seismic vulnerability. This paper focuses on the mechanical challenges of simulating collapse mechanisms in a masonry historical religious complex, significantly damaged during the 2016 Central Italy earthquake. Nonlinear numerical simulations are carried out to model the structure’s response to seismic loads implementing both the Finite Element Method, based on Concrete Damage Plasticity and the Distinct Element Method, studied using two different approaches: Discrete Element Method (DEM) and the Non-Smooth Contact Dynamics (NSCD). Despite their advanced properties in numerical simulation, neither method can fully capture the complexity of masonry collapse mechanisms. Instead, the combined and controlled use of both Finite and Distinct element methods enhances the predictive accuracy of the simulations. Therefore, this study aims to propose a benchmark approach for damage analysis: through a methodological cross-assessment of their respective displacement behaviours, the time-step activations corresponding to local collapse mechanisms are identified. It is then demonstrated that together, these methods offer a more comprehensive approach to detecting collapse mechanism, with reciprocal compensating for the limitations of the other. This synergistic application is essential to address the inherent complexity of masonry mechanics, including material heterogeneity and non-linear failure progression
Alternative approaches to computational mechanics: Blender for the analysis of earthquake-damaged historical buildings
Get PDFThe Italian historical building stock largely consists of masonry structures built without seismic design criteria, making them particularly vulnerable to earthquakes. This structural fragility, combined with the significant seismic hazard of the territory, highlights the need for analysis tools designed to provide reliable assessments within reasonable timeframes. Conventional numerical methods, such as the Discrete Element Method (DEM), while highly accurate, require extensive input data, complex modeling, and significant computational resources, limiting their effectiveness in the preliminary assessment of historic buildings characterized by irregular geometries and heterogeneous materials. This study explores an alternative approach based on the use of Blender, a 3D modeling environment originally developed for graphical purposes, integrated with the Bullet Constraints Builder (BCB) engine. The ability to import point-based geometries and customize deformation behavior through scripting provides a lightweight and flexible tool for simulating structural response up to collapse. The analysis was conducted by applying the approach to the Civic Tower of Amatrice, damaged during the 2016 Central Italy earthquake sequence. Results show that Blender effectively reproduces the stiffness distribution and main deformation patterns, with significantly reduced computational times compared to traditional methods. Although it does not replace more detailed models for the analysis of complex collapse mechanisms, this methodology represents an effective intermediate tool for rapid preliminary assessments of historic structures
On the Dynamics of Masonry Church: Discontinuous and Continuous Approaches
No full textIn a period characterized by the urgent need of ensuring an adequate safety level for the existing buildings according to the present standard codes, the stability evaluation of masonry structures against hazard events has become even more a current challenge. Although the high versatility and durability of masonry, evident difficulties in the structural assessment have been induced by factors such as lack of information in the materials’ properties, irregular geometries, time ageing. To tackle this problem, many modelling techniques in structural analysis have developed, thanks to many scientific studies available in literature. Nevertheless, computational time, discretization procedure, masonry behaviour, contact surface characteristics, loading application, the suitability of geometry complexity, could represent the negative principal aspects. Therefore, the most innovative modelling approaches are critically discussed in this paper. In particular, the aim of this research is to compare the efficiency of a Finite Element (continuous) Method and a Distinct Element (discontinuous) one, both applied for the numerical simulation under lateral loading conditions of a case study, severally damaged by the 2016 Central Italy earthquake. The continuous method is analysed with the Midas FEA NX©. In parallel, the discontinuous methods are studied with 3DEC© and LMGC90© software, where, in turn, different contact conditions are employed. Finally, from this investigation, the main Pros and Cons are highlighted for each method. In detail, the reliability of the discontinuous method could be observed in the accuracy of the failures pattern replicating. On the other hand, the continuous method should allow a fast procedure in the model setting, then remaining as a solution for a preliminary study on the dynamics of the structure
DIFFERENT MODELING APPROACHES APPLIED TO A RESILIENT MASONRY STRUCTURE
No full textIn this paper, advanced numerical models are used to study the progressive damage of a historic building, namely the Palazzo of Podestà and the Civic Tower of Accumoli (central Italy). The dynamic behaviour of the structure is analyzed following important seismic events such as those that occurred in 2016-2017. Discontinuous and continuous approaches are used. In the formers, the masonry response is represented both with Discrete Element Method (DEM) and the Non-Smooth Contact Dynamic (NSCD) method; in the latter the masonry nonlinearity is replicated using the Concrete Damage Plasticity (CDP) model. The numerical results showed a good correspondence of all the approaches with the real damage suffered by the structure after the seismic sequence
Evaluation of the bond behaviour of Steel Reinforced grout applied to curved masonry substrate via bending test
No full textNumerical Assessment of Interacting Structural Units on the Seismic Damage: A Comparative Analysis with Different Modeling Approaches
Get PDFThe conservation of the historical and artistic heritage is one of the main priorities of Italian and international policy. The great variety of masonry buildings that make up this heritage is characterized by different combinations of materials and construction techniques. Then, several damage scenarios could be observed as a result, requiring appropriate retrofitting interventions. A rather accurate structural behavior analysis, especially for horizontal load conditions, allows for elaborating a correct seismic assessment. Albeit there are various numerical tools available to examine them, each one’s process starts by means of certain assumptions that could not be applied indiscriminately. This paper aims to compare two different types of modeling techniques to evaluate their strengths and weaknesses. To achieve this goal, an earthquake-damaged complex in Central Italy was chosen as a case study. The structure was modeled using a finite element (continuous) and a distinct element (discontinuous) method. Both approaches underwent a nonlinear dynamic analysis using the strong motions recorded during the 2016 seismic sequence. The results show that both approaches can evaluate the weak structural points. However, in some cases, the distinct element method appeared more accurate in reproducing the cracks
Retrofitting masonry vaults with Basalt Textile Reinforced Mortar
No full textDue to their slenderness, masonry vaults are particularly vulnerable against unsymmetrical service loads, support displacements and seismic actions. Retrofitting works are therefore needed in numerous existing structures to ensure an adequate safety level according to current standard codes. This paper describes an experimental investigation carried out in the laboratory on two full-scale vault mock-ups. One of them was tested unreinforced, while the other one was strengthened with a basalt mesh applied at the extrados with lime-based mortar. Aiming at reproducing the actual condition of brick vaults in historic constructions, the specimens were provided with buttresses and filling. The load was applied over the filling at 1/3 of the span and increased cyclically up to failure. The tests provided the increase in load-carrying capacity attained with the basalt TRM reinforcement and the modification of the associated failure mode.</jats:p
Sustainable structural health assessment of heritage masonry towers using artificial intelligence and data-driven monitoring: Insights from the civic tower of Matelica
No full textThis paper presents a data-driven Structural Health Monitoring (SHM) framework for the long-term preservation of heritage masonry towers, based on over two years of continuous monitoring of the Civic Tower of Matelica (Italy). Four triaxial energy efficient Micro Electro-Mechanical Systems (MEMS) accelerometers, permanently installed at the tower's corners, provided continuous data analysed using automated Operational Modal Analysis (OMA) and machine learning techniques. The integrated Artificial Intelligence (AI) -assisted approach enables tracking and predictive modeling of the tower's dynamic behavior under environmental and seismic influences, particularly following the 2016/’17 seismic sequence, while adjusting for environmental effects to ensure accurate assessments. The main objective is to assess structural health, reduce invasive inspections and unnecessary interventions, and extend the service life of the structure, thus promoting environmental sustainability. The findings demonstrate the potential of machine learning and AI-assisted SHM for enhancing the resilience and sustainable preservation of historic masonry buildings, offering a replicable model for cultural heritage conservation
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