Limit analysis of loaded out-of-plane rubble masonry : a case study in Portugal

An integrated methodology for the characterization of the response of rubble masonry is presented. The behaviour at collapse of a wall belonging to the Guimarães castle (Portugal) is investigated through a rigid-plastic homogenization procedure, accounting both for the actual disposition of the blocks constituting the walls and texture irregularity, given by the variability of block dimensions. A detailed survey is conducted by means of a photogrammetric technique, allowing for a precise characterization of blocks dimensions and disposition. After a geometric simplification assuming mortar joints reduced to interfaces, homogenized masonry in- and out-of-plane strength domains are evaluated on a number of different representing elements of volume (RVEs) having different sizes and sampled on the walls of the castle. Strength domains are obtained using a finite element (FE) limit analysis with a heterogeneous discretization by triangles and interfaces. Finally, a series of limit analyses are carried out on the façade for the safety assessment under seismic loads by means of two numerical models, the first one being a heterogeneous model and the second a homogenized approach. The reliability of the results, in terms of limit load and failure mechanism, provided by the homogenized model, when compared to the heterogeneous one is satisfactory.(undefined

Characterization of the response of quasi-periodic masonry : geometrical investigation, homogenization and application to the Guimarães castle, Portugal

In many countries, historical buildings were built with masonry walls constituted by random assemblages of stones of variable dimensions and shapes. The analysis of historic masonry structures requires often complex and expensive computational tools that in many cases are difficult to handle, given this large variability of masonry. The present paper validates a methodology for the characterization of the ultimate response of quasi periodic masonry. For this purpose, the behaviour at collapse of a wall at the Guimarães castle in Portugal is investigated by means of a rigid-plastic homogenization procedure, accounting for the actual disposition of the blocks constituting the walls and the texture irregularity given by the variability of dimensions in the blocks. A detailed geometric survey is conducted by means of the laser scanning technique, allowing for a precise characterization of dimensions and disposition of the blocks. After a simplification of the geometry and assuming mortar joints reduced to interfaces, homogenized masonry in- and out-of-plane strength domains are evaluated on a number of different Representing Elements of Volume (RVEs) having different sizes and sampled on the walls of the castle. Strength domains are obtained using a Finite Element (FE) limit analysis approach with a heterogeneous discretization of the RVEs with triangular elements representing units and interfaces (mortar joints), at different orientations of the principal actions with respect to the horizontal direction. The role played by vertical compression is also investigated, considering the case of masonry with weak and strong mortar. Finally, a series of limit analyses are carried out at structural level, using two different FE numerical models of the so-called Alcaçova wall, a representative perimeter wall of the caste. The first model is built with a heterogeneous material and the second model is built with a homogeneous material obtained through the homogenization procedure performed previously. The purpose is to determinate the reliability of results, in terms of limit load and failure mechanism, for the homogenized model and to compare these results to the ones obtained with the heterogeneous model

Survey and characterization of corbelled dome architecture in Northwestern Portugal

The act of overlaying stones to build masonry structures is one of mankind’s most intuitive and resourceful achievements. Masonry buildings can be found all over the world, built with a wide diversity of materials and serving for all kind of purposes. In rural northwestern Portugal, in a granitic highland landscape of scarce resources, for centuries, local farmers used masonry in order to make the territory suitable for farming. In their effort to increase production and, by doing so, to improve their living conditions, a specific mountain agro-pastoral system was developed. Supported by communitarian labour, this system was based on terrace farming and temporary mountain plateau settlements, called brandas, composed of granite corbelled dome buildings. In spite of its perfect adaptation to the harsh local conditions, this heritage’s morphological and typological diversity and constructive inventiveness is endangered due to decades of rural exodus and, thus requiring urgent study and protection. The research project aims to study this heritage from morphological, typological and constructive points of view, with the objective of proposing guidelines towards its preservation. To achieve the established goals, a four stage based methodology was established. Literature review and fieldwork surveys were performed in the first stage, in order to identify possible case studies. On the second stage, an exhaustive geometrical survey and a case study analysis were undertaken and complemented with the local granite’s physical and mechanical characterization. The third stage aims to do an overall structural safety evaluation of the corbelled domes, based on numerical analysis. In the final stage, consolidation and preservation guidelines to safeguard this architectural heritage will be proposed. This paper presents the results of the first stage, along with a glimpse of the second stage.The authors wish to express their gratitude to the Municipality of Arcos de Valdevez, for all the support given, and to the Equipa de Sapadores Florestais do Gabinete Técnico Florestal do Município e da Associação Floresta Atlântica. The first and fifth authorswishto express theirgratitude to the Portuguese Science and Technology Foundation for the scholarshipsgranted (SFRH/BD/ 86704/2012 and SFRH/BD/112646/2015).This work was supported by FCT, within ISISE, project UID/ECI/04029/2013

Parameterization of structural faults in large historical constructions for further structural modelling thanks to laser scanning technology and computer vision algorithms

Laser scanning technology has evolved significantly in the last decade, particularly, in those applications in terrestrial environments dealing with the documentation and inspection of civil engineering and architectural constructions. Even though there exist mature procedures to convert the so-called LiDAR point clouds in CAD models or even FEM models, the current trends in the technology are related to the automation of these operations. The development of robust automatic procedures for data segmentation and interpretation it is a key aspect so that the technology can definitely be accepted as a basic, accurate, and robust tool for reverse engineering of existing constructions. This paper presents the application of laser scanning technology to the structural evaluation of the Medieval Wall of Guimarães (Portugal). This laser scanning survey was conducted with the aim of having an accurate and detailed geometrical model of the large masonry construction that includes the existing deformations and structural faults. The parameterization of structural damages was possible thanks to the highly detailed point cloud collected, and its processing using computer vision algorithms. The geometric models obtained could be used for further structural analysis of the entire wall.This work has been partially supported by the Spanish Ministry of Interior (Grant SPIP2017-02122), Spanish Ministry of Economy, Industry and Competitiveness (Grant: EUIN2017-87598), and Xunta de Galicia through grant ED431C2016‐038

The construction of the transhumance territory of the Gerês-Xurés: Vernacular heritage identification, analysis and characterization

In order to ensure survival, the rural populations of the Gerês-Xurés mountain range transboundary region developed, over centuries, a very specific system of vertical transhumance. Focus on making the most out of their natural landscape harsh conditions, human intervention shaped the territory, and gave birth to the existent and very authentic vernacular heritage, that has in the corbelled dome building technologies one of its most characteristic identity features. In the pursuit of fertile land, villages were scattered in small and compact settlements, built at lower altitude and occupied all year long. The surrounding mountain’s slopes were turned into farming terraces, and the high-altitude plateaus were for livestock and farming, thru temporary settlements built in corbelled dome structures. These vital points were interconnect by a dense network of paths and masonry walls. Although the resemblance between most of the region permanent settlements, the temporary nuclei, due to each mountain particular features, show a large morphological and functional diversity, from complex structures, like the “brandas” or the “brandas e inverneiras” system, to very simple pasture areas, like the “currais”. Understanding the high potential of this endanger vernacular heritage is a key point for its preservation, as well as its recognition by the scientific community and society in general. A previous study aimed at the “brandas” morphological and constructive characterization was presented at the Rehabend 2016. This follow-up study is focus on, in a first level, the identification and characterization of the general system main features, and, in a second level, the evaluation of this vernacular heritage main preservation threats. The research, based on case studies analysed thru fieldwork surveys, geometrical and constructive, and literature support, allowed to identify the main morphological and typological features related to the heritage elements that take part in this occupation system, and are discussed in this paper.Portuguese Science and Technology Foundation for the scholarships granted (SFRH/BD/ 86704/2012 and SFRH/BD/112646/2015). This work was supported by FCT, within ISISE, project UID/ECI/04029/201

Semi-automated creation of accurate FEM meshes of heritage masonry walls from point cloud data

The structural analysis of buildings requires accurate spatial models. Additionally, pathologies such as settlement-induced damages are paramount in the assessment of heritage assets. This spatial information is used as a basis for Finite Element Method (FEM) meshes to evaluate the stability of the structure. Traditional data acquisition approaches rely on manual measurements which are labor intensive and error prone. Therefore, major simplifications are made to document structures efficiently. The goal of this research is to provide faster and more accurate procedures to capture the spatial information required by a FEM. This paper presents a semi-automated approach to create accurate models of complex heritage buildings for the purpose of structural analysis. By employing non-destructive techniques such as terrestrial laser scanning and photogrammetry, a complex mesh of the structure is created. Also, a methodology is proposed to capture crack information. A stepwise approach is elaborated to illustrate how the spatial information is adapted towards a FEM mesh. The results show a significant difference between the geometry our model and a traditional wire- frame model. Not only does accurate modelling result in deviating loads, it also affects the behavior of the object. Through the proposed approach, experts can develop highly accurate FEM meshes to assess the stability of the structure up to as-built conditionsPostprint (published version

Criterios de Interpretación de la Edad en los Otolitos del Lirio o Bacaladilla (Micromesistius poutassou) del Atlántico Nordeste

Este manual tiene como objetivo describir los métodos para la determinación de la edad anual del lirio o bacaladilla (Micromesistius poutassou, Risso 1810). Las técnicas para la determinación de la edad en estructuras calcificadas de especies pelágicas y bentónicas (disección, preparación y métodos) en el área del ICES (aguas atlánticas europeas) se han descrito recientemente en un manual publicado tanto en inglés como en castellano (Villamor et al., 2015; 2016). Este nuevo manual que presentamos aquí se centra sólo, pero en mayor profundidad, en los criterios utilizados y estandarizados a nivel europeo para la interpretación de los anillos de crecimiento anual en los otolitos (lectura de otolitos) del lirio del Atlántico Nordeste. Este manual tiene como finalidad servir de referencia para los lectores de edad del lirio en los laboratorios del IEO y pretende también ser una guía para el entrenamiento de los nuevos lectores en la determinación de la edad en los otolitos del lirio, para suplementar y complementar el entrenamiento que reciben del lector experto asignado para entrenarlos. También pretende ser una guía dinámica, que pueda cambiar a medida que sean introducidos nuevos criterios de interpretación tras ser evaluados y adoptados a nivel europeo. Este manual se basa en los últimos intercambios, talleres y publicaciones sobre la determinación de la edad del lirio (ICES, 2005; 2013). También se hace referencia a la biología de la especie ya que es fundamental tener conocimiento de ella para poder interpretar los otolitos con mayor precisión

Criterios de Interpretación de la Edad en los Otolitos de la Sardina (Sardina pilchardus) Atlántica Europea

Este manual tiene como objetivo describir los métodos para la determinación de la edad anual de la sardina (Sardina pilchardus, Walbaum, 1792). Las técnicas para la determinación de la edad en estructuras calcificadas de especies pelágicas y bentónicas (disección, preparación y métodos) en el área del ICES (aguas atlánticas europeas) se han descrito recientemente en un manual publicado tanto en inglés como en castellano (Villamor et al., 2015; 2016). Este nuevo manual que presentamos aquí se centra solo, pero en mayor profundidad, en los criterios utilizados y estandarizados a nivel europeo para la interpretación de los anillos de crecimiento anual en los otolitos (lectura de otolitos) de la sardina Atlántica Europea. Este manual tiene como finalidad servir de referencia para los lectores de edad de la sardina en los laboratorios del IEO y pretende también ser una guía para el entrenamiento de los nuevos participantes (lectores) en la determinación de la edad en los otolitos de sardina, para suplementar y complementar el entrenamiento que reciben del lector experto asignado para entrenarlos. También pretende ser una guía dinámica, que pueda cambiar a medida que sean introducidos nuevos criterios de interpretación tras ser evaluados y adoptados a nivel europeo. Este manual se basa en los últimos intercambios, talleres y publicaciones sobre la determinación de la edad de la sardina (ICES, 2005; 2011). También se hace referencia a la biología de la especie ya que es fundamental tener conocimiento de ella para poder interpretar los otolitos con mayor precisión

Age determination procedures for pelagic and benthic species from ICES area in Spanish Institute of Oceanography (IEO)

This handbook presents a summary of the age estimation procedures used in Spanish Institute of Oceanography (IEO) for some of the main commercial small and medium pelagic species and benthic species of the Spanish fleet. It provides information about the sampling program, otolith extraction and preparation, and the age estimation criteria. A summary of the information related to the age accuracy, validation and corroboration of each species is also presented, as well as that related to the age precision, quality control and verification