Innovative retrofitting materials for brick masonry infill walls

Dissertação de mestrado em Structural Analysis of Monuments and Historical ConstructionsLast seismic events in Southern Europe have highlighted the vulnerability in the most usual constructive typology in contemporary architecture: framed structures with masonry infills. Contemporary structures have a good capacity to withstand these actions, given that they were considered for their design according to modern codes. Nonetheless, nonstructural elements as masonry infills show a high degree of damage even for medium magnitude earthquakes, causing casualties and high economic losses. For decades, these elements have been considered as nonstructural and therefore they were not requested to have resisting conditions. Given this, there is a large segment within the building stock in seismic prone areas that needs to undergo preventive action, specially for out-of-plane loads. This can range from a mere union of the infills to the frame structures to a reinforce of the elements, which can also be applied to the case of already damaged elements. The potential benefits go beyond the mere stability of nonstructural elements, as this would improve the behaviour of the whole structure to face seismic events. Some new fibre-based materials for structural reinforcement based in braiding techniques have been developed in the last years in the Universidade do Minho, as an alternative to conventional FRP rods. These materials have several advantages, out of which it can be remarked the possibility of designing the composition according to mechanical requirements and the implication of low-tech and low-cost procedures for its production. The main purpose on this thesis will be the assessment of the application of this material as reinforcement for clay brick masonry, using the technique of Textile Reinforced Mortars, considering out-of-plane actions. This has been done through a basic experimental campaign in which it has been evaluated the improvement in the behaviour of masonry samples subjected to flexural loads. The material was applied with variations in reinforcement ratio in order to have some parametrical confrontation. Other samples included commercial solutions, so as to have a reference on already existing materials, and the control samples were unreinforced. The obtained results for the innovative materials were highly satisfying in terms of ductility enhancement, obtaining big deformations with a considerable flexural capacity, and a considerable increase in strength. Furthermore, the use of different materials within a composite results in the combination of its properties. The future development and enhancement of this material presents a high potential as an economic and easy to apply method for brick masonry reinforcement, with the possibility of tailor-made properties.Os recentes eventos sísmicos ocorridos no sul da Europa destacaram as vulnerabilidades de um dos sistemas construtivos mais utilizados na arquitectura contemporânea: estruturas em pórtico preenchidas com paineis de alvenaria. Enquanto as estruturas modernas, dimensionadas de acordo com os códigos em vigor, resistem bem a esse tipo de acções, o mesmo já não se passa com os elementos não-estruturais. De facto, é comum os paineis de alvenaria sofrerem elevados danos, mesmo para sismos de intensidade media, causando vitimas fatais e elevadas perdas económicas. Durante décadas estes elementos foram considerados como sendo não-estruturais e consequentemente nunca lhes foi exigido quaisquer propriedades the resistência. Sendo assim, é natural que nas zonas sismicas exista uma larga porção de patrimonio edificado com necessidade de sofrer medidas preventivas, especialmente para acções fora do plano.Estas medidas podem significar desde a simples união dos paneis à estrutura até um reforço dos elementos individuais da alvenaria, o qual pode ser aplicado mesmo que já existam danos. Os potenciais benefícios destas técnicas vão para além da mera estabilidade destes elementos uma vez que o seu reforço poderá implicar uma mehoria das caracteristicas sismicas da estrutura como um todo. Durante os últimos anos a Universidade do Minho tem vindo a desenvolver novos materiais à base de fibras como alternativa aos sistemas convencionais de polimetros reforçados com fibras (FRP).. Estes materiais possuem várias vantagens entre as quais se destaca a possibilidade de poderem ser dimensionados com base em requisitos mecânicos de uma forma barata e tecnologicamente acessível. O principal objectivo desta tese é a avaliação da aplicação deste material como reforço de alvenaria de tijolo cerâmico, utilizando a técnica de argamassas reforçadas com texteis e considerando acções fora do plano. Este estudo foi realizado através de uma série de ensaios experimentais simples, na qual foi avaliada a melhoria do comportamento de várias amostras sujeitas a cargas de flexão. Vários espécimens foram preparados com diferentes densidades de reforço, de modo a possibilitar a comparação de vários parâmetros. Outras amostras incluíram soluções comerciais, de forma a ter uma referência de materiais já existentes, e amostras de controlo não-reforçadas. Os resultados obtidos para os materiais inovadores foram altamente satisfatórios em termos de aumento de ductilidade, tendo-se verificado deformações elevadas enquanto mantendo uma capacidade de suporte de carga considerável, e um aumento da capacidade de carga no estado fendilhado. O continuado desenvolvimento e aperfeiçoamento destes materiais apresenta um elevado potencial, sendo um método economico e de fácil aplicação em alvenaria de tijolo cerâmico.Los últimos eventos sísmicos en el Sur de Europa han puesto de relieve la vulnerabilidad de una de las tipologías constructivas más usuales de la arquitectura contemporánea: las estructuras porticadas –metálicas o de hormigón- con cerramientos de ladrillo. Si bien las estructuras soportan bien las acciones, los elementos no estructurales como fachadas o petos sufren graves daños, provocando altas pérdidas económicas y víctimas mortales incluso para acciones sísmicas de mediana magnitud. Durante décadas, estos elementos constructivos se han considerado no estructurales, y por tanto no se les han exigido condiciones de resistencia. Nos encontramos por tanto con un amplio sector del parque inmobiliario en zonas de riesgo sísmico necesitado de acciones de prevención. Dichas acciones incluyen una mejor unión de los cerramientos a la estructura general, así como posibles refuerzos de los elementos en sí. El beneficio, más allá de la estabilidad de los elementos en sí, incluye un mejor comportamiento de la estructura general ante acciones sísmicas En la Universidade do Minho se han venido desarrollando nuevos materiales de refuerzo estructural, basados en la técnica del entrenzado de fibras, como alternativas a las barras de FRP convencionales. Estos materiales están compuestos por un núcleo de material resistente rodeado de una funda entrenzada de material económico, que mejora la adherencia del material al mortero a la vez que protege al núcleo del ataque alcalino. Entre sus ventajas, la posibilidad de diseñar composiciones del material dependiendo de los requerimientos mecánicos y el uso de una tecnología sencilla y de bajo coste. La producción y caracterización de estos materiales será tratada a fondo en este trabajo. La validación de estos nuevos materiales en su aplicación al refuerzo de muros de fábrica de ladrillo se ha hecho mediante una campaña experimental básica, comprobando la mejora que supone su uso en la resistencia a flexión unidireccional de unas muestras de obra de fábrica, realizados con los materiales más usuales para esta solución constructiva. Se ha intentado confrontar el resultado de estos materiales, con parámetros variables, con el de materiales disponibles comercialmente, así como con muestras de control sin refuerzo. Los resultados obtenidos para los materiales desarrollados son muy satisfactorios en cuanto a la mejora de la ductilidad, obteniendo grandes deformaciones manteniendo la capacidad de carga, incluso para ratios de refuerzo relativamente bajos. Para los ejemplares con más refuerzo, se observa además una redistribución de tensiones dentro de la fábrica, dando lugar a un fallo a flexión muy dúctil y a un comportamiento con incremento de resistencia en el estado fisurado. El desarrollo de este material presenta una gran potencialidad como método económico y de fácil aplicación para el refuerzo de muros de fábrica

Psychophysical Determination of the Relevant Colours That Describe the Colour Palette of Paintings

In an early study, the so-called “relevant colour” in a painting was heuristically introduced as a term to describe the number of colours that would stand out for an observer when just glancing at a painting. The purpose of this study is to analyse how observers determine the relevant colours by describing observers’ subjective impressions of the most representative colours in paintings and to provide a psychophysical backing for a related computational model we proposed in a previous work. This subjective impression is elicited by an efficient and optimal processing of the most representative colour instances in painting images. Our results suggest an average number of 21 subjective colours. This number is in close agreement with the computational number of relevant colours previously obtained and allows a reliable segmentation of colour images using a small number of colours without introducing any colour categorization. In addition, our results are in good agreement with the directions of colour preferences derived from an independent component analysis. We show that independent component analysis of the painting images yields directions of colour preference aligned with the relevant colours of these images. Following on from this analysis, the results suggest that hue colour components are efficiently distributed throughout a discrete number of directions and could be relevant instances to a priori describe the most representative colours that make up the colour palette of paintings.FEDER Funds by the Spanish Ministry of Science Innovation and Universities (MICINN, grant number RTI2018-094738-B-I00

Understanding the effect of correlated colour temperatures on spatio-chromatic properties of natural images

Despite the natural occurrence of global and local daylight changes in natural scenes, the human visual system typically adapts well to these changes and develops stable colour perception. In a previous study, the influence of daylight characterized by its Correlated Colour Temperatures (CCT) on different chromatic descriptors was analysed (Ojeda et al., 2017). The results showed that chromatic information is almost constant for CCT values above 14,000 K, with local extremes occurring in the range of low CCTs. The aim of this work is to extend the analysis of the CCT dependence of the illuminant to those that consider the spatio-chromatic structure, including second order descriptors (gradients, spectral slope, spectral signature, and PCA) and higher order descriptors (kurtosis, skewness, and number of relevant colours). Our results show that most of the descriptors exhibit horizontal asymptotic behaviour for CCTs above 15,000 K and local extremes in the range of 3,900 K-9,600 K. For those descriptors that could be analysed in CIELAB space, sufficient statistical evidence was obtained to consider skewness, kurtosis, and the independent spectral slopes of the L* channel as equal in the range of CCTs used. However, the slight variations in spectral signatures and the directions of the principal components when applying PCA to image patches are not statistically significant and cannot be considered equal under different illuminants. The number of relevant colours (NRC) exhibits sensitivity to temperature variations and behaves similarly to the other descriptors, due to its small number.Computational Colour and Spectral Imaging Erasmus+ master programme (610605-EPP-1-2019-1-NO-EPPKA1-JMD-MOB

Estudio de interrelaciones entre el cuento La reina de las nieves y Frozen, el reino del hielo (Propp, Andersen, Disney)

Las páginas que se desarrollan a continuación proponen como base fundamental una comparación entre la narración de Andersen: La reina de las nieves y la adaptación del mismo cuento por Disney en Frozen, el reino del hielo. Dos medios diferentes, el literario y el audiovisual nos servirán para unir mediante el anclaje directo de la obra de Vladimir Propp: Morfología del cuento maravilloso sus contrastes y similitudes en aspectos funcionales y estructurales en relación al mismo. Un análisis posterior de corte analítico-descriptivo en nuestra acotada investigación nos lleva a encontrar otros intereses igualmente importantes, relacionados con la narratología y simbología en los que se presentan de igual forma analogías y contrastes. Las sorpresas no quedan exentas a pesar de la diferencia de edad de las publicaciones exploradas

Computational color analysis of paintings for different artists of the XVI and XVII centuries

We have performed a computational color analysis of images of paintings for six master painters: Titian, Rubens, El Greco, Velázquez, Rembrandt, and Vermeer. These painters show the evolution from the renaissance to the baroque style. Different first and second-order statistical parameters have been obtained and analyzed in order to fix which of them can be common for the different artists and which of them can be representative of a certain period of time or the evolution of the art. The firsts include the orientation and semi-axes ratio of the ellipses that define the gamut in the chromaticity diagram and the dependencies with the frequency of the power of the Fourier transforms. Most differences among artists can be found in the volume and area of the gamut, the number of discernible colors which is greater for Titian, El Greco and Rubens, compared to Velázquez, Rembrandt and Vermeer, the average value of L* and the number of dark pixels.Ministerio de Industria Economia y Competitividad for their support and grant in the project DPI 2015-6471_

Household poultry production northern Tolima (Colombia)

Páginas 64-67Este artículo muestra los resultados obtenidos en un estudio transversal en cuatro municipios de la zona norte del departamento del Tolima (Colombia) con el fin de caracterizar la avicultura familiar en la comunidad. In formación sobre producción avícola, nivel tecnológico, sistemas de alimentación, consumo y contribución a la economía familiar fue recolectada mediante entrevistas a los granjeros. El principal fin de este componente productivo es el autoconsumo. En 2006 el 55, 62 y 78% de familias de cada grupos (C1, C2, C3, respectivamente) criaron aves. Las principales limitaciones identificadas son las deficiencias en la alimentación, la ausencia de asistencia técnica, la presencia de enfermedades. Los resultados sugieren que la avicultura familiar representa una oportunidad para contribuir al mejoramiento de las condiciones de vida de las familias campesinas, especialmente de las mujeres, para lo cual se requiere que la actividad ocupe un lugar relevante en la agenda de las instituciones de desarrollo de investigación.ABSTRACT. This article shows results of a research project related to household poultry production carried out in the peasant communities of four northern municipalities of Departamento del Tolima (Colombia), to characterize backyard poultry production and small poultry farms. Information on poultry production, technological level, feeding systems, and consumption and contribution to household income was collected through identified farmer in terviews. The main purpose of this production system is as food for the household. In 2006 55, 62 y 78 % of households of each group (C1,C2,C3, respectively) were raising poultry. Poultry feeding and nutrition practices, management, and presence of diseases were identified as the main limitations. Results suggest that backyard poultry and small poultry farms production systems contribute to the improvement of living standards of peasant households, especially those of women, and therefore should be included as a priority in the research agenda of institutions promoting research

Improving the structural reliability of steel frames using posttensioned connections

In this paper, various moment-resisting steel frames (MRSFs) are subjected to 30 narrow-band motions scaled at different ground motion intensity levels in terms of spectral acceleration at first mode of vibration in order to perform incremental dynamic analysis for peak and residual interstory drift demands. The results are used to compute the structural reliability of the steel frames by means of hazard curves for peak and residual drifts. It is observed that the structures exceed the threshold residual drift of 0.5%, which is perceptible to human occupants, and it could lead to human discomfort according to recent investigations. For this reason, posttensioned connections (PTCs) are incorporated into the steel frames in order to improve the structural reliability. The results suggest that the annual rate of exceedance of peak and residual interstory drift demands are reduced with the use of PTC. Thus, the structural reliability of the steel frames with PTC is superior to that of the MRSFs. In particular, the residual drift demands tend to be smaller when PTCs are incorporated in the steel structures.Peer ReviewedPostprint (published version

Las ganancias de señalizar en el mercado laboral en Cali

Este artículo discute el efecto de la educación sobre los salarios en la ciudad de Cali para el año 2000. En particular se discute tanto el modelo de capital humano como el modelo de señalización derivado de la ecuación de títulos de Hungerford y Solon (1987). Los resultados muestran que existe una rentabilidad adicional del título universitario del 37% sobre los salarios y del 12% para el título de secundaria. Finalmente se discute la necesidad de realizar una encuesta que permita identificar mejor el efecto de los títulos sobre los salarios.Títulos