2,952 research outputs found
Historic city centers after destructive seismic events, the case of finale Emilia during the 2012 Emilia-Romagna earthquake: Advanced numerical modelling on four case studies
No full textIntroduction: The recent wave of seismic shocks in Central Italy (2016) had once more disastrous consequences for the local monuments, which consisted of old masonry churches and towers. The permanent, seismic-induced damage to cultural heritage has become a serious issue that can no longer be downsized, and questions have been raised about how to satisfactorily assess the vulnerability of such heritage in advance. This paper deals with the investigations into the actual condition of a historic city center partially destroyed by the seismic sequence occurred in May 2012 in Emilia-Romagna. Namely, the case of Finale Emilia â a small to medium-sized village located at the very center of the stricken area â is considered. Methods: Three important heritage masterpieces were numerically analyzed using Finite Element meshes to deepen the knowledge of their seismic vulnerability and try to avoid similar disasters in the future. The first structure is a masonry castle known as âCastello delle Roccheâ, which underwent severe damages during the seismic sequence. The second and third examples deal with the structural analysis of two towers, both collapsed due to the quakes: the Fortified Tower of the castle and the Clock Tower of the village. The last analysis is devoted to study the seismic behavior of a medium-sized masonry church (Santa Maria del Rosario), heavily damaged by the seismic sequence and whose bell tower collapsed due to the formation of a hinge at mid-height. Results and Conclusion: Numerical models were created for all the buildings involved, and a variety of advanced analyses were carried out, including nonlinear static and dynamic ones, to have a deep insight into their expected vulnerability, also finding reasonable correspondence between the numerical results and the actual state of damage observed during the surveys made in the aftermath of the seismic events
In- and out-of-plane analysis of multi-leaf masonry walls via an elementary homogenized numerical procedure
No full textAn elementary homogenized numerical procedure for the analysis of multi-leaf walls is discussed, capable of describing both in- and out-of-plane behaviors. Multi-leaf walls are frequent features in old European masonry structures, and they usually collapse during earthquakes due to their scarce resistance to out-of-plane loads. The procedure first consists in the generation of a 2D FE mesh to represent a masonry test-window, and second in the derivation of the in- and out-of-plane homogenized failure surfaces. The in-plane surface of the multi-leaf is obtained through a weighted average among the homogenized stresses of each layer. Afterwards, the out-of-plane bending moment is calculated from the resulting in-plane surfaces of each layer, under the assumption of a constant distribution over the thickness of the homogenized stress. The global out-of-plane failure surfaces of the multi-leaf are then evaluated as the sum of the various homogenized moments. The procedure is applied to two test-windows displaying distinct block layouts: one is running bond masonry consisting of tuff blocks; the other is rubble masonry consisting of stones. The results indicate a greater resistance of rubble masonry than for running bond, both for the in- and out-of-plane behaviors
Homogenized failure surfaces of rubble masonry
No full textThe mesoscale averaging procedure known as homogenization has been widely used over the past decades to draw the global mechanical behavior of masonry starting from that of its constitutive materials. However, its application to rubble masonry structures apparently discords with identification of a Representative Element of Volume, a basic cell capable of generating the considered block arrangement if translated. In this work, a simple Matlab code aiming at deriving homogenized failure surfaces for rubble masonry is presented, inspired by the successful approach developed in a previous work by other researchers and based on the idea of test-windows. After creating a 2D FE mesh from the sketch of a masonry test-window, the code allows the evaluation of homogenized failure surfaces in the tension-tension range. A practical application is carried out by comparing the results on two different textures (running bond v. rubble masonry)
A novel pixel limit analysis homogenization model for random masonry
No full textThe application of homogenization techniques to non-periodic masonry structures is apparently in disagreement with the very idea behind homogenization itself, which is the possibility to identify a repetitive cell able to generate the masonry pattern under translation. However, few past works have attempted to overcome this issue with satisfactory results. One side issue arising when dealing with such an irregular masonry pattern is the generation an effective finite element mesh starting from the image of a randomly-assembled masonry panel. In this work, a Matlab code able to create a mesh directly from a picture is presented, and is subsequently employed in a broader code for the derivation of homogenized failure surfaces for in-plane loaded masonry test-windows
Comprehensive FE numerical insight into Finale Emilia Castle behavior under 2012 Emilia Romagna seismic sequence: Damage causes and seismic vulnerability mitigation hypothesis
No full textIn this paper, a numerical insight on the historical masonry Castle of Finale Emilia, symbol of the consequences occurred after the seismic sequence of 20-29th May 2012 in Emilia Romagna, Italy, is presented. Some different numerical models are critically compared, in order to both have an insight into the causes at the base of the partial collapse of the structure and propose valuable rehabilitation interventions with seismic upgrading to prevent future damage under seismic loads. Two different meshes are utilized, the one very refined and constituted by tetrahedron elements, the other much coarser and mainly constituted by hexahedrons, along with different hypotheses presented for the masonry material (linear and elasto-plastic with damage and softening).The analyses performed include standard modal, nonlinear static (pushover) and nonlinear dynamic analyses, under different hypotheses concerning the material properties of the single walls. Three different configurations are compared, the first is the real one stricken by the earthquake (where only one of the walls had been consolidated), the second is a hypothetical castle without any consolidated wall, the last is the situation that should be encountered after full rehabilitation. At this aim, full three-dimensional (3D) detailed finite element models (FEM) are adopted, starting from the available documentation at disposal (photos and existing drawings). From numerical results, it is found that the insufficient resistance of the constituent materials is mostly responsible for the damages observed and that the partial rehabilitation implemented by the municipality on one wall helped in limiting the damaging effect of the seismic sequence. In all cases, the numerical analyses provide a valuable picture of active damage mechanisms, giving useful hints for the reconstruction and indicating that a limited upgrading of masonry mechanical properties could limit considerably the global seismic vulnerability of the structure, in light of a reconstruction of the collapsed parts of the Castle
Rozpor ako východisko, láska ako smer u Simone Weilovej (Contradiction as base, Love as direction in writings of Simone Weil)
No full textArticle is explaining contradiction and love, Simone Weil‘s essential terms of hermeneutics of human Being. It introduces close relation of these terms with her understanding of God as well as with her overall concept of religion. Author also mentions Simone Weil‘s inspirations with philosophical and spiritual concepts of the East
ASM variants in the spotlight:A structure-based atlas for unraveling pathogenic mechanisms in lysosomal acid sphingomyelinase
No full textLysosomal acid sphingomyelinase (ASM), a critical enzyme in lipid metabolism encoded by the SMPD1 gene, plays a crucial role in sphingomyelin hydrolysis in lysosomes. ASM deficiency leads to acid sphingomyelinase deficiency, a rare genetic disorder with diverse clinical manifestations, and the protein can be found mutated in other diseases. We employed a structure-based framework to comprehensively understand the functional implications of ASM variants, integrating pathogenicity predictions with molecular insights derived from a molecular dynamics simulation in a lysosomal membrane environment. Our analysis, encompassing over 400 variants, establishes a structural atlas of missense variants of lysosomal ASM, associating mechanistic indicators with pathogenic potential. Our study highlights variants that influence structural stability or exert local and long-range effects at functional sites. To validate our predictions, we compared them to available experimental data on residual catalytic activity in 135 ASM variants. Notably, our findings also suggest applications of the resulting data for identifying cases suited for enzyme replacement therapy. This comprehensive approach enhances the understanding of ASM variants and provides valuable insights for potential therapeutic interventions.</p
“I beg you to tell me what has become of Djamila”: The Political Mobilization of Simone de Beauvoir’s Readers During the Boupacha Affair
No full textBy Sophia Millman This is a condensed version of a Masters thesis dedicated to the political mobilization of Simone de Beauvoir’s readers. The citations from the letters were translated from French by the author. *** On June 2, 1960, the French government ordered all copies of the daily Algiers edition of Le Monde seized and destroyed to suppress the publication of Simone de Beauvoir’s article “Pour Djamila Boupacha.” Beauvoir, a self-professed “woman of letters”, not “of action[1]”, and one ..
A Genetic Algorithm adaptive homogeneous approach for evaluating settlement-induced cracks in masonry walls
No full textThis paper presents a Genetic Algorithm adaptive homogeneous approach aiming at representing the crack patterns induced by ground settlements on masonry walls. This type of damage is a critical issue since it affects all masonry buildings, including those that are not located in seismic-prone areas. The GA-adaptive homogeneous approach here proposed is meant as a tool that overcomes the usual high computational costs requested by the traditional heterogeneous and homogeneous approaches. Here, the considered masonry wall is discretized into a low number of 2D polygonal elements; its displacement field is then determined through a linear programming problem. The actual position of cracks induced by the applied settlement is identified by modifying the initial mesh through an iterative mesh adaptation procedure performed with a Genetic Algorithm (GA); the
iterations are carried on until the absolute minimum of the work performed by the reaction forces is attained. In this way, the computational effort needed for identifying the actual crack patterns is dramatically decreased due to the very few unknowns of the problem. The reliability of the GA-adaptive homogeneous approach here proposed is validated against selected benchmarks that come from experimental and numerical results, and is also compared with the traditional heterogeneous and homogeneous approaches. In all the three benchmarks, the GA-adaptive approach offers a satisfying computational efficiency and identifies the actual crack patterns with good accuracy, despite the low number of elements employed in the discretization of the masonry wall. This may pave the way for a broader use of this approach in the analysis of complex masonry structures affected by settlement-induced damages
AN INNOVATIVE VOXEL-BASED APPROACH FOR THE OUT-OF-PLANE HOMOGENIZED LIMIT ANALYSIS OF NON-PERIODIC MULTI-LEAF MASONRY WALLS
No full textA recurring construction technique in many European countries (Italy included) is based on the erection of multi-leaf walls. Their seismic vulnerability is usually high, due to the fact that the wythes are poorly or by no means connected one each other. Hence, masonry buildings with multi-leaf walls regularly display an insufficient strength against out-of-plane actions (such as those caused by earthquakes and those causing the highest vulnerability), which leads to partial or total collapse. This paper proposes a novel approach devoted to the out-of-plane analysis of masonry multi-leaf walls at collapse, with special attention given to the case of non-periodic masonry - in which the units display different geometries and are randomly arranged in the walls. This approach is based on the so-called “voxel strategy”, in which the 3D finite element mesh of a multi-leaf wall is created directly from the rasterized images of its external wythes. Every pixel of the rasterized images is transformed into its 3D counterpart (the “voxel”, indeed), which is then converted into a solid finite element. The “voxel strategy” for generating the finite element mesh is translated into a MATLAB function, which is itself part of a broader limit analysis approach based on the upper bound theorem, that aims at deriving homogenized out-of-plane failure surfaces. These represent macroscopic out-of-plane strength criteria for the selected non-periodic multi-leaf masonry walls; they are expressed in terms of flexural and torsional moments around the horizontal and vertical axes of the considered wall. The approach also enables the extraction of the deformed shapes at collapse for single out-of-plane load conditions. The homogenized out-of-plane failure surfaces are the results of an upper bound limit analysis problem coupled with homogenization, aptly formulated as a standard-form linear programming problem. The solid finite elements of the created mesh are rigid, and the velocity jumps at the interfaces between adjacent finite elements obey a Mohr-Coulomb failure criterion with separate tension and compression cut-offs and associated flow rule. A case study is investigated to benchmark the procedure, namely a rubble masonry three-leaf wall with absente interconnection between leaves
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