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Abordagem baseada no desempenho em edifícios de alvenaria através de análise experimental e numérica pushover
No full textTese de doutoramento em Civil EngineeringOs edifícios de alvenaria não aramada constituem uma percentagem significativa do parque imobiliário
e têm uma extensa história. Avanços recentes na investigação experimental e numérica fizeram
progressos notáveis no projeto de estruturas sismo-resistentes e na construção de edifícios de alvenaria
não armada. Este trabalho investiga o efeito da irregularidade do plano, um dos principais parâmetros
que influenciam o comportamento sísmico dessas estruturas, avaliando as implicações da torção na
resposta devido à irregularidade do plano. O presente trabalho pretende colmatar a lacuna de
investigação associada a ensaios quase estáticos em edifícios de alvenaria não armada com diafragma
rígido e irregularidade em planta. O programa experimental incluiu caracterização dos materiais, testes
cíclicos quase estáticos, testes de identificação dinâmica e correlação de imagens digitais num modelo
experimental em escala reduzida (1:2). A partir dos resultados dos cíclicos quase estáticos, foi possível
obter o comportamento pós-pico do edifício e definir estados limite de desempenho associados a
determinado nível de deformação e consequente dano. Os limites de desempenho foram considerados
inferiores aos indicados nos códigos e que estão associados a mecanismos rotura no plano. Considerase
que a definição dos limites de desempenho deve ser realizada em termos de mecanismos de dano
combinados e não apenas no comportamento no plano de componentes individuais no caso de um
edifício com um diafragma rígido e com irregularidade no plano. Um conjunto de dados consistente foi
obtido e posteriormente utilizado para calibração e validação de modelos numéricos, nomeadamente
propriedades de materiais, parâmetros chave que caracterizam resposta quase estática do modelo
experimental e parâmetros resultantes da identificação dinâmica do modelo experimental. No que diz
respeito à análise numérica, para além de uma comparação de diferentes abordagens de modelação
com o objetivo de avaliar diferenças nos resultados de modelação de edifícios de alvenaria, foi elaborado
um modelo numérico do edifício experimental com base em elementos finitos. Para este efeito, optou-se
pela abordagem de macro modelação contínua para simular a resposta experimental, tendo-se obtido
resultados confiáveis. Os ensaios de identificação dinâmica tiveram um papel muito importante na
calibração dos modelos numéricos. Os resultados das análises experimentais e numéricas revelaram a
importância de se considerar a interação entre a resposta no plano e fora do plano na avaliação do
desempenho sísmico em edifícios de alvenaria com diafragmas rígidos.Unreinforced masonry buildings constitute a significant percentage of global building stock and have an
extensive history. These structures were built according to intangible and intuitive principles, shaped by
generations of experience, traditional methods, and cultural knowledge. Recent advances in experimental
and numerical research have made noteworthy progress in earthquake-resistant design and construction
of these buildings. Following past earthquakes, seismic codes encourage the design of regular structures,
which is an idealised concept and often challenging to achieve in the context of unreinforced masonry
(URM) buildings. This thesis investigates plan irregularity, one of the key parameters influencing the
seismic behaviour of such structures, assessing the implications of torsional effects on response due to
plan irregularity. This research integrates experimental study with numerical simulations, such as cyclic
quasi- static testing and pushover analyses. While shake-table tests have been common in experimental
testing, the present thesis intends to address the research gap linked to quasi-static tests on unreinforced
masonry buildings with rigid diaphragm and plan irregularity. The experimental programme included
characterisation of the materials, cyclic quasi-static testing, dynamic identification tests, and digital image
correlation on a half-scale two-story residential building. By performing cyclic quasi-static testing, the
post- peak behaviour of the building was achieved, and performance limits were identified. The
performance limits were found to be lower than those ruled by the codes relevant to in-plane mechanisms.
It is considered that the definition of damage limits should be carried out in terms of combined damage
mechanisms rather than solely on the in-plane behaviour of single components when a rigid diaphragm
and plan irregularity are present. As a result, a consistent dataset of material properties, quasi-static
response, and modal behaviour was obtained and later used for input and validation of numerical models.
Concerning numerical modelling, besides a benchmark among different numerical approaches aiming at
analysing discrepancies in results in modelling masonry buildings, a representative finite element method
model of the experimental building was prepared. The continuum macro-modelling approach simulated
the experimental response effectively and reliable results were achieved. Dynamic identification tests
played a significant role in the calibration of the numerical models where model updating was carried out
considering tuning modulus of elasticity. The findings from both experimental and numerical analyses
highlighted the importance of considering in-plane and out-of-plane responses of masonry buildings with
rigid diaphragms when performance-based assessment is of relevance in the structural analysis.This PhD thesis is financially supported by the Portuguese Foundation for Science and Technology (FCT) through the individual PhD Scholarship SFRH/BD/143949/2019 and COVID/BD/153438/2023
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Pushover analysis of unreinforced irregular masonry buildings: Lessons from different modeling approaches
Get PDFThe present paper addresses the seismic performance of a half-scale two-story unreinforced masonry (URM) building with structural irregularity in plan and in elevation. The main objectives are (i) to understand the seismic response of URM buildings with torsional effects, and (ii) to evaluate the reliability of using simplified approaches for irregular masonry buildings. For this purpose, nonlinear static analyses are carried out by using three different modeling approaches, based on a continuum model, beam-based and spring-based macro-element models. The performance of each approach was compared based on capacity curves and global damage patterns. Reasonable agreement was found between numerical predictions and experimental observations. Validation of simplified approaches was generally provided with reference to regular structures but, based on the differences in the base shear capacity found here, it appears that structural irregularities are important to be taken into account for acquiring higher accuracy on simplified methods when torsion is present.The first author acknowledges the financial support from the Portuguese Foundation for Science and Technology (FCT) through the Ph.D. Grant SFRH/BD/143949/2019. This work is financed by national funds through FCT, in the scope of the research project "Experimental and Numerical Pushover Analysis of Masonry Buildings (PUMA) (PTDC/ECI-EGC/29010/2017)
Cyclic quasi-static testing of a half-scale, two-story unreinforced masonry building with structural irregularity
Get PDFPushover analysis is a straightforward tool to be applied in engineering practice to validate a numerical method, or to use performance-based design/assessment methods. Yet, a limited number of the experimental campaign, which studies the building response in a quasi-static regimen, exists. In the present study, cyclic quasi-static testing of a half-scale two-story unreinforced masonry building with structural irregularity has been performed at the Laboratory of the Structures at the University of Minho. A typical building typology has been selected and the structural irregularity is introduced by a setback in one corner of the building plan. The loading has been applied as unidirectional at the centre of mass to observe the torsional effects due to irregularity. In the present paper, the testing procedure, and the main experimental findings are presented and discussed
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Quasi-static test on a half-scale two-story URM building: mechanical chracterization [i. é characterization] of materials
No full textNonlinear static (pushover) analysis has been often preferred to evaluate the seismic response of buildings in practice owing to its simplicity. Yet, a straightforward application is not available and further improvements are essential to implement pushover analysis and their use for URM buildings. In addition, validation of new numerical procedures is mainly developed by comparing capacity curves attained from the pushover curve with envelope curve obtained from shaking table tests. It is important to reduce the number of parameters that may influence the response due to the analysis type. Thus, numerical procedures that have been used in engineering practice can be improved to ensure more accurate simulations for design and assessment through a quasi-static test. Within this context, the present paper addresses an experimental campaign of half-scale two-story URM building with plan irregularity and material characterization tests have been performed to have an insight on the mechanical properties that is essential for numerical modeling.The first author acknowledges the financial support from the Portuguese Foundation for Science and
Technology (FCT) through the Ph.D. Grant SFRH/BD/143949/2019. This work was financed by
national funds through FCT - National Foundation for Science and Technology, I.P., in the scope of
the research project “Experimental and Numerical Pushover Analysis of Masonry Buildings (PUMA)”
(PTDC/ECI-EGC/29010/2017)
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