Structural, seismic and geotechnical analysis of the Sant' Agostino church in L'aquila (Italy)

A menudo, las construcciones existentes en albañilería son el resultado de construcciones, cambios y modificaciones que se han ido desarrollando durante siglos. Por lo tanto, las adaptaciones y mejoras de las edificaciones en albañilería deben ir acompañadas de un nivel adecuado de conocimiento de su historia. Las trágicas consecuencias de los recientes terremotos ocurridos en Italia y otros países, han llevado a pensar que, a veces, la causa del daño sísmico podría ser justamente una errada intervención de la mejora o adaptación que se les ha realizado. En la mayoría de los casos, este hecho es atribuible a las modificaciones realizadas sin tener los conocimientos necesarios sobre las normas constructivas de esa edificación. El estudio de caso presentado en este trabajo se refiere al análisis sísmico de la iglesia de Sant' Agostino en L'Aquila (gravemente dañada por el sismo ocurrido en abril de 2009), y considera en profundidad los tres niveles de evaluación de la seguridad sísmica establecidos en el Código Italiano para la evaluación y reducción del riesgo sísmico del patrimonio cultural Eurocode 8: Design of structures for earthquake resistance, (2003), Decreto Legislativo (2004), Norme tecniche per le costruzioni, DM. (2005), Norme tecniche per le costruzioni, DM. (2008), Circolare n. (2010), Direttiva del Presidente del Consiglio dei ministri per la valutazione e la riduzione del rischio sismico del patrimonio culturale con riferimento alle Norme Tecniche per le Costruzioni. G.U. (2008). Así, para el LV1 (Nivel de evaluación 1) se realizaron todos los análisis exigidos en los anexos de la Directiva del 10 de diciembre de 2007, comenzando por el Módulo A que corresponde al "registro de identificación", continuando con el Módulo B que se refiere al estudio de los "factores de sensibilidad" y finalizando con el Módulo C que considera la "morfología de los elementos". A partir de esta evaluación, hemos concluido que la aceleración máxima del terreno durante el sismo del 6 de abril de 2009 superó el valor de aceleración correspondiente a los estados límite de colapso. Para el LV2 (Nivel de evaluación 2), nos enfocamos principalmente en la verificación de todos los macroelementos como una fuente potencial del mecanismo de daños. Descubrimos que los mecanismos ocurridos estaban mayormente relacionados con la fachada, la nave, la cúpula, el ábside/presbiterio, la techumbre, capillas laterales, las juntas entre la alineación horizontal y vertical, y por último, el campanario. Un vez recopilados todos los datos relacionados con el sitio, la geometría de la construcción, las características de los materiales, la estructura, el suelo, etc., realizamos un análisis modal a la estructura utilizando el Método de Elemento Finito dinámico (FEM, en inglés), válido para el LV3 (Nivel de evaluación 3). Además, estos ensayos dinámicos son esenciales para la evaluación de la seguridad sísmica y poseen la ventaja de no ser destructivos. Finalmente, el análisis entregó los modos de vibración más importantes y sugirió las intervenciones estructurales óptimas para reparar el daño existente y evitar la formación de los mismos mecanismos bajo la acción de un futuro sismo. Existing masonry buildings are often the result of constructions, changes and alterations that have developed over the centuries. Therefore, the adaptation and improvement of existing masonry buildings must be accompanied by an adequate level of knowledge of their history. The tragic consequences of the recent earthquakes, in Italy and abroad, have stimulated the belief that, sometimes, the cause of seismic damage might be just the wrong intervention of improvement or adaptation. in most cases, this is attributable to retrofit works which are carried out without any knowledge concerning the construction rules of the building. The case study presented here regards the seismic analysis of the Sant' Agostino Church in LAquila (seriously damaged by the earthquake occurred in April 2009), which takes into account the in-depth knowledge of the factory, respecting all three evaluation levels of seismic safety provided by the Italian seismic Guidelines for Cultural Heritage (Eurocode 8, 2003; NTC, 2008). In particular for LV1 (Evaluation Level 1), all the analyses requested to fill the annexes of the Directive of December 10th, 2007 were carried out, starting from Module A, which is the "identifier registry", passing through Module B, which concerns the study of "sensitivity factors", and ending with Module C, which considers the "morphology of the elements". From this examination, we concluded that the ground acceleration during the earthquake of April 6th, 2009 surpassed the acceleration value corresponding to the limit state of collapse. For LV2 (Evaluation Level 2), we especially focused on the verification of all macro-elements as a potential source of damage mechanisms. in particular, we found that these mechanisms concerned mostly the facade, the hall, the dome, the apse/presbytery, the roofing, the side chapels, the joints between horizontal and vertical alignment, and finally, the bell tower. Once we collected all data regarding the site, the geometry of construction, the characteristics of the materials, the structure, the soil, etc., we carried out a dynamic FEM modal analysis on the structure, valid for LV3 (Evaluation Level 3). Moreover, these dynamic tests are essential for the evaluation of seismic safety and they also present the clear advantage of being non-destructive. Finally, the analysis provided the most significant vibration modes and suggested the optimal structural interventions to remedy the existing damage and prevent the formation of these mechanisms under the action of future earthquakes

La escalera de ojo abierto del Palacio Di Majo en Nápoles entre geometría y equilibrio

The staircases represent one of the most impressive architectural expressions of the building. Many authors presented a great deal of research over the years on this matter intending to understand how they are designed and laid out. This paper is concerned with a particular structural type of masonry staircase, known as stair with open well or roman staircase. It aims to demonstrate that in masonry-vaulted staircases, the close relationship between the shape and static behavior is particularly evident, and geometry and construction are essential for their stability. The authors have proved this statement by studying Palazzo Di Majo’s open-well staircase in Naples, whose main structure consists of tuff vaults. The first part of the article is substantially descriptive and presents an in-depth description of the geometric and architectural features of the stair. The second part explains all the aspects concerning the equilibrium of this kind of stairways, within Heyman’s theory of masonry.  Las escaleras representan una de las más imponentes expresiones arquitectónicas del edificio. Varios autores han presentado muchas publicaciones a lo largo de los años sobre este tema para entender cómo han sido diseñadas y cómo se sostienen. Este trabajo se trata sobre un tipo específico de escalera de albañilería, conocida como escalera “de ojo abierto” o “a la romana”. El objetivo es demostrar que en las escaleras con bóvedas de fábrica existe una estrecha relación entre la forma y su comportamiento estático. La geometría y la construcción son imprescindibles para su estabilidad. Los autores han demostrado esta tesis estudiando la escalera de ojo abierto del Palacio Di Majo en Nápoles, cuya estructura principal está constituida por bóvedas de toba. La primera parte del artículo presenta una descripción detallada de las características geométricas y arquitectónicas de la escalera. La segunda parte, explica el equilibrio de estas escaleras a partir de la teoría del equilibrio de estructuras de fábrica de Heyman

The open-well staircase of Palazzo Di Majo in Naples between geometry and equilibrium | La escalera de ojo abierto del Palacio Di Majo en Nápoles entre geometría y equilibrio

The staircases represent one of the most impressive architectural expressions of the building. Many authors presented a great deal of research over the years on this matter intending to understand how they are designed and laid out. This paper is concerned with a particular structural type of masonry staircase, known as stair with open well or roman staircase. It aims to demonstrate that in masonry-vaulted staircases, the close relationship between the shape and static behavior is particularly evident, and geometry and construction are essential for their stability. The authors have proved this statement by studying Palazzo Di Majo’s open-well staircase in Naples, whose main structure consists of tuff vaults. The first part of the article is substantially descriptive and presents an in-depth description of the geometric and architectural features of the stair. The second part explains all the aspects concerning the equilibrium of this kind of stairways, within Heyman’s theory of masonry

The majolica dome of Santa Maria della Sanità in Naples. Geometric configuration analysis and stability studies | La cúpula de mayólica de Santa Maria della Sanità en Nápoles. Configuración geométrica y estudios de estabilidad

This article deals with the survey and representation of the dome of Santa Maria della Sanità in Naples (Italy). The survey led to a geometric analysis of the spatial configuration of the dome, the drawing of its majolica decoration and its structural behavior. The overall objectives of this research can be briefly outlined as follows. First, the study focuses on defining the correct geometry of the dome obtained through accurate surveys. Finally, the study performs a simplified structural analysis of the compound dome-buttress system set within the theoretical framework of the Limit Analysis through the graphical statics

The algal diversity in the Phlegrean Fields (Campania, Italy) archeological districts: an overview

The coexistence of several ecological conditions (hot springs, streams, mud, rock walls), characterized by different pH, temperature values, water potential and mineralogical makes the Phlegrean Fields as an ideal area for the analysis of the microalgal assemblages and their relationships with the different microhabitats occurring in the sites. Here we report an overview of the algal diversity within the archaeological and geothermal areas of Phlegrean Fields and the adaptability for most of them to acidic and thermal conditions in the volcanic soils

The algal diversity in the Phlegrean Fields (Campania, Italy) archeological districts: an overview

The coexistence of several ecological conditions (hot springs, streams, mud, rock walls), characterized by different pH, temperature values, water potential and mineralogical makes the Phlegrean Fields as an ideal area for the analysis of the microalgal assemblages and their relationships with the different microhabitats occurring in the sites. Here we report an overview of the algal diversity within the archaeological and geothermal areas of Phlegrean Fields and the adaptability for most of them to acidic and thermal conditions in the volcanic soils

Equilibrium of masonry vaults and open stairs

In this paper the unilateral model for masonry is applied to explain the equilibrium of vaults. In particular, the present study is concerned with the application of the safe theorem of limit analysis to spiral vaults, that is, curved constructions modeled as continuous unilateral bodies. On allowing for singular stresses in the form of line or surface Dirac deltas, statically admissible stress fields concentrated on surfaces (and on their folds) lying inside the masonry, are considered. The unilateral restrictions require that the membrane surface lies in between the extrados and intrados surfaces of the vault and that the stress function, representing the stress, be concave. Such a constraint is, in general, not satisfied on a given shape for given loads: in such a case, the shape has to be modified to fit the constraint. A particular application, namely the double spiral stair of Sanfelice’ palace in Naples, is considered

Cyanidium chilense (Cyanidiophyceae, Rhodophyta) from tuff rocks of the archeological site of Cuma, Italy

Phlegrean Fields is a large volcanic area situated southwest of Naples (Italy), including both cave and thermoacidic habitats. These extreme environments host the genus Cyanidium; the species C. chilense represents a common phototrophic micro- organism living in anthropogenic caves. With a view to provide a comprehensive characterization for a correct taxonomic classification, morpho-ultrastructural investigations ofC. chilense from Syb’s cave (Phlegren Fields) was herein car-ried out and compared with the thermoacidophilic C. caldarium. The biofilm was also analyzed to define the roleofC. chilensein the establishment of a bio film within caveenvironments. Despite the peculiar ecological and molecular divergences,C. chilenseandC. caldariumshared all the maindiacritic features, suggesting morphological convergence within the genus; cytological identity was found amongC. chilensestrains geographically distant and adapted to different substrates, such as the porous yellow tuff of Sybil cave and calcyte, magnesite and basaltic rocks from other caves. C. chilense is generally dominant in all biofilms, developing monospecific islets, developing both super ficially or betweenfungal hyphae and coccoid cyanobacteria. Extracellular polymeric substances (EPS) were recorded in C. chilense bio filmsfrom Sybil cave, confirming the role of EPS in facilitating cellsadhesion to the surface, creating a cohesive network of inter-connecting biofilm cell

Cryptic dispersal of Cyanidiophytina (Rhodophyta) in non-acidic environments from Turkey

Cyanidiophytina are a group of polyextremophilic red algae with a worldwide, but discontinuous colonization. They are restricted to widely dispersed hot springs, geothermal habitats, and also some human-altered environments. Cyanidiophytina are predominant where pH is prohibitive for the majority of eukaryotes (pH 0.5-3). Turkey is characterized by areas rich in volcanic activity separated by non-volcanic areas. Here we show that Cyanidiophycean populations are present in thermal baths located around Turkey on neutral/alkaline soils. All known genera and species within Cyanidiophytina were detected in Turkey, including Galdieria phlegrea, recorded up to now only in Italian Phlegrean Fields. By phylogenetic analyses, Turkish G. sulphuraria strains are monophyletic with Italian and Icelandic strains, and with Russian G. daedala strains. G. maxima from Turkey clustered with Icelandic, Kamchatka, and Japanese populations. The discovery of Cyanidiophytina in non-acidic Turkish soils raises new questions about the ecological boundaries of these extremophilic algae. This aids in the understanding of the dispersal abilities and distribution patterns of this ecologically and evolutionarily interesting group of algae