Parametric study of a historical masonry building subjected to seismic loading

Dissertação de mestrado em Structural Analysis of Monuments and Historical ConstructionsEarthquakes are one of the natural hazards that have caused more losses to the mankind. Besides countless human lives, earthquakes have destroyed buildings and even cities in many places and civilizations around the world. However, the nature and origin of earthquakes, as well as their effect in built structures, have been studied in detail only recently. An important factor that influenced the progress of this science is the development of computing, which allowed to carry out complex calculations. In parallel to that, many researches have been done in the last years aimed at understanding and reproducing the effects of earthquakes in built structures. Thanks to the combination of new methods of structural analysis and powerful computing resources, accurate approaches of the behavior of a specific structure can be done nowadays. The two more widely used structural analysis methods are adopted in this thesis, namely Pushover Analysis and Time Integration Analysis. The Finite Element Method (FEM) is used to model a case study and to discuss the obtained results in detail. The case study is a ‘‘Gaioleiro’’ building, a traditional stone masonry typology used mainly in Lisbon, Portugal, between the 19th and 20th century. The study of this building started years ago with a shaking table test carried out by the National Laboratory of Civil Engineering in Lisbon (LNEC), together with University of Minho. Subsequently, a FEM model was calibrated by other authors according to the results obtained in this test. The present thesis starts with a brief introduction, some basic background about seismic engineering and a brief description of the adopted FEM model. Then the results obtained for the model with Pushover and Time History Analyses are discussed, with the aimed to contribute for the validation and application of pushover analysis in the seismic assessment of historical masonry buildings without box behavior. The main body of the thesis includes a sensitivity analysis intended to assess the influence of the material properties in the behavior of the structure, as well as the impact of rigid diaphragm floor structures and the load pattern distribution in the response of the building. The sensitivity analysis is performed for both Pushover and Time History Analyses, in order to discuss the objectivity of the results.Os terremotos são um dos perigos naturais que causaram mais perdas para a humanidade. Além de inúmeras vidas humanas, os terremotos destruíram edifícios e até cidades em muitos lugares e civilizações ao redor do mundo. No entanto, a natureza e a origem de sismos, bem como o seu efeito em estruturas construídas, têm sido estudadas em detalhe apenas recentemente. Um fator importante que influenciou o progresso desta ciência é o desenvolvimento da computação, o que permitiu a realização de cálculos complexos. Em paralelo a isso, muitas investigações têm sido feitas nos últimos anos que visam compreender e reproduzir os efeitos de terremotos em estruturas construídas. Graças à combinação de novos métodos de análise estrutural e recursos computacionais poderosos, as abordagens precisas do comportamento de uma estrutura específica podem ser feitas hoje em dia. Os dois métodos de análise estrutural mais utilizados são adotados nesta tese, a saber a Análise Pushover e Análise dinâmica com integração no tempo. O Método dos Elementos Finitos (MEF) é usado para modelar um estudo de caso com estas técnicas e discutir os resultados obtidos em detalhe. O caso de estudo é um edifício gaioleiro, uma tipologia tradicional de alvenaria de pedra usado principalmente em Lisboa, Portugal, entre os séculos XIX e XX. O estudo deste edifício começou há alguns anos com um ensaio de mesa sísmica realizado pelo Laboratório Nacional de Engenharia Civil, em Lisboa (LNEC), em conjunto com a Universidade do Minho. Subsequentemente, um modelo MEF foi calibrado por outros autores de acordo com os resultados obtidos neste teste. A presente tese começa com uma breve introdução, algumas informações básicas sobre engenharia sísmica e uma breve descrição do modelo MEF adotado. Em seguida, os resultados obtidos para o modelo com Análises Pushover e com integração no tempo são discutidos, com o objetivo de contribuir para a validação e aplicação de análise avançada na avaliação sísmica de edifícios históricos de alvenaria sem comportamento do tipo caixa. O corpo principal da tese inclui uma análise de sensibilidade destinada a avaliar a influência das propriedades do material no comportamento da estrutura, bem como o impacto da rigidez da de diafragma do pavimento e do padrão de distribuição de carga na resposta do edifício. A análise de sensibilidade é realizada tanto para Pushover como para a integração no tempo, a fim de discutir a objetividade dos resultados.Los terremotos son uno de los fenómenos naturales que han causado más pérdidas en la historia de la humanidad. Aparte de incontables vidas humanas, los terremotos han destruido edificios e incluso ciudades enteras en muchos lugares y civilizaciones diferentes alrededor del mundo. Sin embargo, la naturaleza y origen de los terremotos, así como su efecto en las estructuras, han sido estudiados en detalle solo en tiempos recientes. Un factor importante que ha influido en el progreso de esta rama de la ingeniería es el desarrollo de la informática, que ha permitido llevar a cabo cálculos complejos. En paralelo a esto, muchas investigaciones han sido realizadas en los últimos años, enfocadas a comprender y reproducir los efectos de los terremotos en las estructuras. Gracias a la combinación de nuevos métodos de análisis estructural y potentes recursos computacionales, aproximaciones precisas del comportamiento de una estructura específica ante cargas estáticas y dinámicas pueden ser realizados actualmente. Los dos métodos de análisis estructural más ampliamente usados en el campo académico son adoptados en esta tesis, a saber; análisis de Pushover y análisis de tiempo-historia. El método de elementos finitos (MEF) es usado para modelar el objeto de estudio y discutir en detalle los resultados obtenidos. El objeto de estudio es un edificio ‘‘Gaioleiro’’, una tipología tradicional basada en albañilería de piedra y usada principalmente en Lisboa, Portugal, entre los siglos 19 y 20. El estudio de este edificio comenzó hace años con un ensayo realizado en una mesa de vibración por el Laboratorio Nacional de Ingeniería Civil (LNEC) en Lisboa, junto con la Universidad de Minho. Posteriormente, un modelo realizado con el método de elementos finitos fue calibrado por otros autores de acuerdo con los resultados obtenidos en este ensayo. La presente tesis comienza con una breve introducción, algunos conocimientos básicos sobre ingeniería sísmica y una breve descripción del modelo adoptado. Los resultados obtenidos con el análisis de Pushover y de tiempo-historia son analizados y discutidos. El principal objetivo de este análisis es la contribución en la validación y aplicación del análisis de Pushover en la valoración sísmica de edificios históricos de albañilería sin comportamiento de ‘‘caja’’. El cuerpo principal de la tesis incluye un análisis de sensibilidad con el objeto de evaluar la influencia de las propiedades de los materiales en el comportamiento de la estructura, así como el impacto que diafragmas rígidos y diferentes patrones de distribución de cargas pueden tener en la respuesta del edificio. El análisis de sensibilidad es llevado a cabo para ambos análisis, los de Pushover y de tiempo-historia para discutir la objetividad de los resultados

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

SEISMIC STRENGTHENING OF REINFORCED CONCRETE COLUMNS WITH STRAIGHT CARBON FIBRE REINFORCED POLYMER (CFRP) ANCHORS

After consulting key members of the industry (BBR ConTech, Opus International, Fulton Hogan and Beca) it was found that, while the most common failure of RC columns is shear failure, the shear strengthening of RC columns with FRP anchors is fairly well known by engineers, and they are confident in their design. Flexural strengthening of RC columns with FRP anchors is a complex and unknown application and only one example of a research focused on this technique could be found in the existing literature. In addition to verify the applicability of the design equation previously developed, a few aspects not covered in the component tests will be investigated: • The effect of tensile-compression cycles • The effect of dynamic loading • The interaction between adjacent anchors • The behaviour of edge anchors • The effect of overlapped fan components • Behaviour on real case specimen • Effect of different confinement schemes • Effect of different anchor sizes • Strengthening of columns with lap splice failur

Shear strengthening of an RC column and wallet with FRP anchors

Graphic representation of a shear strengthening of an RC column and wallet with FRP anchor

Straight FRP anchors dataset

Data set of 72 experiment