Structural behaviour of stainless steel frames. Safety against accidental seismic actions

Tesi amb menció de Doctorat Internacional(English) Stainless steel is one of the most promising construction materials due to its long service life, low maintenance requirements, excellent mechanical properties and high residual value. Nevertheless, for an efficient design with stainless steel, it is fundamental to account for the nonlinear effects of the material at all structural levels. Stainless steel design codes have improved significantly in recent decades, although they are still far from being as comprehensive as those for carbon steel, on which they are usually based. There has been little progress in the design of stainless steel structural systems subjected to static forces, and even less in the seismic design of stainless steel structures, for which no standard exists in Europe or the US. This thesis constitutes a significant step towards the understanding of the performance of stainless steel systems under different loading types, addressing aspects of the global behaviour of stainless steel structures under static and seismic forces with the aim of proposing design expressions that guarantee more optimised and safer structures. Thus, this thesis presents the first known comprehensive experimental programme on stainless steel systems, in which four austenitic portal frames were tested under vertical and horizontal loading, and a detailed explanation of the different problems encountered in the planning and testing process is given in the document. The obtained results made it possible to validate, with experimental evidence, the design prescriptions included the Eurocode for the consideration of second order effects accounting for the influence of the nonlinear response of the material through the amplification of the horizontal forces. In addition, an alternative design method for the in-plane design of stainless steel structures under static loading is presented. The method is based on performing a second order structural analysis, and the material nonlinearities and different structural imperfections are considered by reducing the stiffness of the members through a set of proposed factors, requiring only cross-section checks to be performed. In contrast to the commonly adopted European approach, where a first order nonlinear material analysis is performed, this alternative design approach is typical of the US regulatory framework. Regarding the cyclic behaviour of stainless steel structures, this thesis investigates experimentally and numerically the performance of stainless steel cold-formed rectangular hollow section members under cyclic loading, focusing on the rotation capacities. The correct estimation of the rotation capacity allows establishing the actual capacity of the structure. A simple formulation to estimate the rotation capacity is proposed in terms of the local slenderness, and calibrated for the three main stainless steel families, which in turn allows the description of the full moment-rotation curves. Furthermore, this thesis studies the seismic performance of stainless steel moment resisting frames designed according to the new European design rules for carbon steel systems. Design adaptations and a new design formula to effectively account for material nonlinearities in the seismic design of these structures are proposed. The actual behaviour factors of stainless steel frames are assessed from a number of case studies, and new values of the behaviour factors for stainless steel moment resisting frames in the European and US design frameworks are recommended. Finally, this thesis investigates the post-necking behaviour of stainless steels under monotonic loading and proposes preliminary values for the key parameters of two common ductile fracture models to provide a material model that defines the response of stainless steels up to failure. One possible application of such model would be in the simulation of joint failure, which can be implemented in new design approaches that study structures as a whole, such as the Direct Design Method.(Español) El acero inoxidable es uno de los materiales de construcción más prometedores debido a su larga vida útil, escasa necesidad de mantenimiento, excelentes propiedades mecánicas y alto valor residual. Sin embargo, para un diseño eficiente con acero inoxidable, es fundamental tener en cuenta los efectos no lineales del material en todos los niveles estructurales. Los códigos de diseño del acero inoxidable han mejorado notablemente en las últimas décadas, aunque aún distan mucho de ser tan exhaustivos como los del acero al carbono, en los que suelen basarse. Se ha avanzado poco en el proyecto de sistemas estructurales de acero inoxidable sometidos a cargas estáticas, y menos aún en el diseño sísmico de estructuras de acero inoxidable, para el que no existe ninguna norma en Europa ni en los Estados Unidos. Esta tesis constituye un avance significativo hacia la comprensión del comportamiento de los sistemas de acero inoxidable bajo diferentes tipos de carga, abordando aspectos del comportamiento global de las estructuras de acero inoxidable bajo cargas estáticas y sísmicas con el objetivo de proponer expresiones de cálculo que garanticen estructuras más optimizadas y seguras. Así, esta tesis presenta el primer programa experimental conocido sobre sistemas de acero inoxidable sometidos a cargas verticales y horizontales, y ofrece una explicación detallada de los diferentes problemas encontrados en el proceso de planificación y ensayo. Los resultados obtenidos permitieron validar, con pruebas experimentales, las prescripciones de cálculo incluidas en el Eurocódigo para la consideración de los efectos de segundo orden teniendo en cuenta la influencia de la respuesta no lineal del material a través de la amplificación de las fuerzas horizontales. Además, se presenta un método de cálculo alternativo para el diseño de estructuras de acero inoxidable bajo cargas estáticas. El método se basa en la realización de un análisis estructural de segundo orden, y las no linealidades del material y las diferentes imperfecciones estructurales se consideran reduciendo la rigidez de los elementos mediante un conjunto de factores propuestos, requiriendo únicamente la comprobación de la sección transversal. En cuanto al comportamiento cíclico de las estructuras de acero inoxidable, esta tesis investiga experimental y numéricamente el comportamiento de los elementos de acero inoxidable de sección hueca rectangular conformados en frío bajo cargas cíclicas, centrándose en las capacidades de rotación. La estimación correcta de la capacidad de rotación es de suma importancia porque permite establecer la capacidad real de la estructura. A partir de los resultados obtenidos, se propone una formulación sencilla para estimar la capacidad de rotación en términos de la esbeltez local, que se calibra para las tres principales familias de acero inoxidable, y que permite describir las curvas momento-rotación completas. Además, esta tesis estudia el comportamiento sísmico de pórticos resistentes a momento de acero inoxidable diseñados según las nuevas normas europeas de cálculo para sistemas de acero al carbono. Se proponen adaptaciones de las normas y una nueva fórmula para considerar la no linealidad del material en el diseño sísmico de estas estructura. También se evalúan los factores de comportamiento reales de los pórticos de acero inoxidable a partir de una serie de casos estudiados, y se recomiendan nuevos valores de estos factores en los marcos de diseño europeo y estadounidense. Por último, esta tesis investiga el comportamiento de los aceros inoxidables bajo cargas monotónicas después de alcanzar su resistencia última, y propone valores preliminares para los parámetros clave de dos modelos comunes de fractura dúctil. Una posible aplicación de dichos modelos sería en la simulación del fallo de uniones, que puede implementarse en nuevos enfoques de cálculo que estudian las estructuras en su conjunto, como el Método de Diseño Directo.Postprint (published version

The use of acronyms in nursing English: implications for the development of communicative competence

This paper analyzes the use of acronyms in nursing English, and its implications for the development of the communicative competence of the speakers of this special language. The starting assumption is that profuse use of acronyms is a defining feature of scientific genre and hence of nursing language. Evidence for this assumption is provided by the data obtained from a corpus of articles published in specialized nursing journals. The paper is organized as follows. First, the term ‘acronym’ is defined. Then, nursing acronyms are classified according to their degree of lexicalization. Next, I focus on acronym formation. Finally, I deal with the rules that govern acronym usage, and examine several examples to see both compliance and non-compliance with these rules. From the analysis of these examples, several conclusions are drawn

Mujeres pioneras de la arquitectura española

Con el objetivo de sacar a la luz las biografías de mujeres españolas que hayan sido pioneras en sus respectivos campos, una vez superadas las grandes dificultades de todo tipo, fundamentalmente de género, que tuvieron que sufrir para conseguir ese hito y que, sin embargo, son prácticamente desconocidas para la sociedad en general, esta comunicación está dedicada a recordar la vida e historia de las mujeres españolas que destacaron por ser las primeras en conseguir alguna distinción en el campo de la Arquitectura. Se muestran así, entre otras, de forma breve, las biografías de las primeras mujeres españolas tituladas en esa disciplina y las primeras catedráticas universitarias relacionadas con la misma. También, y a efectos de contextualización, se dan unas breves pinceladas de las biografías de las primeras mujeres arquitectas no españolas.With the aim of exposing the biographies of Spanish women who have been pioneers in their respective fields, once overcome the great difficulties of all kinds, mainly gender, who she had to suffer to achieve that milestone and that, however, they are practically unknown to society in general, this communication is dedicated to remember the life and history of the first Spanish women who stood out for being the first to get some distinction in the field of Architecture. In this way, the biographies of the first Spanish women with a degree in that discipline and of the first university professors related to it are shown. Also, and for the purposes of contextualization, brief strokes of the biographies of the first non-Spanish women architects are given

Relación entre cultura organizativa y reputación de una empresa

Tanto cultura organizativa como reputación son términos que se utilizan habitualmente en el mundo empresarial, ya que ambos pueden conseguir ventajas competitivas sostenibles en el tiempo. Sin embargo, pocos son los estudios que se adentran a relacionar ambos conceptos, tan relevantes en el funcionamiento de las empresas. Por ello, el objetivo de este trabajo es demostrar, de forma teórica, la relación positiva entre la cultura organizativa que posee una organización y su reputación, para a continuación plantear la metodología que se podría seguir a la hora de mostrar la evidencia empírica de tal vinculación

Steps to ensure a successful implementation of occupational health and safety: Interventions at an organizational level

There is increasing meta-analytic evidence that addresses the positive impact of evidence-based occupational health and safety interventions on employee health and well-being. However, such evidence is less clear when interventions are approached at an organizational level and are aimed at changing organizational policies and processes. Given that occupational health and safety interventions are usually tailored to specific organizational contexts, generalizing and transferring such interventions to other organizations is a complex endeavor. In response, several authors have argued that an evaluation of the implementation process is crucial for assessing the intervention’s effectiveness and for understanding how and why the intervention has been (un)successful. Thus, this paper focuses on the implementation process and attempts to move this field forward by identifying the main factors that contribute toward ensuring a greater success of occupational health and safety interventions conducted at the organizational level. In doing so, we propose some steps that can guide a successful implementation. These implementation steps are illustrated using examples of evidence-based best practices reported in the literature that have described and systematically evaluated the implementation process behind their interventions during the last decade

Posición jurídica y problemática en el control judicial de los actos administrativos subjetivos, que conoce el Consejo de Estado y confronta la Corte Constitucional

Este artículo de reflexión describe, la posición jurídica del Consejo de Estado y de la Corte Constitucional frente al control judicial de los actos administrativos de carácter individual, contiene una revisión bibliográfica fundamentada en fuentes doctrinarias y jurisprudenciales sobre el control judicial de las acciones de nulidad y nulidad y restablecimiento del derecho. El desarrollo de la investigación comprende una etapa de recuperación de información y otra de análisis jurisprudencial, tratando de describir modelos que permitan identificar variables sobre las cuales se puede incidir para actuar sobre el problema jurídico planteado. Los resultados de este trabajo presentan la óptica jurídica de cada corporación en el control judicial de los actos administrativos subjetivos, los cuales serán de utilidad como reflexión jurídica en el campo académico y judicial. El artículo se desarrolla en la ciudad de Bogotá D.C. durante el curso de la especialización en derecho administrativo, recibiendo la orientación metodológica del tutor y docentes, haciendo posible la validez académica del mism

Teachers’ views of corporate reputation: Influence on behavioral outcomes

The aim of this paper is to analyze the influence of teachers’ views of corporate reputation on behavioral outcomes in educational cooperatives. Educational cooperatives are social companies that must adequately manage their intangible assets to improve their competitiveness in the education sector. However, research on how teachers perceive corporate reputation is limited. Data was obtained through a survey of 101 teachers to test the research model proposed using path analysis. The findings highlight that teachers’ views of corporate reputation in educational cooperatives have significant and positive effects on employee satisfaction, retention and perceived service quality. Likewise, employee satisfaction has significant effects on teacher retention and perceived service quality. Therefore, given that employee satisfaction is a relevant variable in an educational organization’s operation, employees’ views of corporate reputation can be used as a strategic tool to manage and improve organizational outcomes

Ceramide Kinase inhibition blocks IGF-1-mediated survival of otic neurosensory progenitors by impairing AKT phosphorylation

Sphingolipids are bioactive lipid components of cell membranes with important signal transduction functions in health and disease. Ceramide is the central building block for sphingolipid biosynthesis and is processed to form structurally and functionally distinct sphingolipids. Ceramide can be phosphorylated by ceramide kinase (CERK) to generate ceramide-1-phosphate, a cytoprotective signaling molecule that has been widely studied in multiple tissues and organs, including the developing otocyst. However, little is known about ceramide kinase regulation during inner ear development. Using chicken otocysts, we show that genes for CERK and other enzymes of ceramide metabolism are expressed during the early stages of inner ear development and that CERK is developmentally regulated at the otic vesicle stage. To explore its role in inner ear morphogenesis, we blocked CERK activity in organotypic cultures of otic vesicles with a specific inhibitor. Inhibition of CERK activity impaired proliferation and promoted apoptosis of epithelial otic progenitors. CERK inhibition also compromised neurogenesis of the acoustic-vestibular ganglion. Insulin-like growth factor-1 (IGF-1) is a key factor for proliferation, survival and differentiation in the chicken otocyst. CERK inhibition decreased IGF-1-induced AKT phosphorylation and blocked IGF-1-induced cell survival. Overall, our data suggest that CERK is activated as a central element in the network of anti-apoptotic pro-survival pathways elicited by IGF-1 during early inner ear development.This work was supported by the Spanish Ministerio de Economia y Competitividad, project FEDER/SAF2017-86107-R to IVN and MM.Peer reviewe

Efecto antimicrobiano in vitro del aceite esencial de matricaria chamomilla y cúrcuma longa combinados con CAOH2 frente al enterococcus faecalis atcc 29212

Comparar el efecto antimicrobiano in vitro del aceite esencial de Matricaria chamomilla y Curcuma longa embebidos con CaOH 2 frente al Enterococcus faecalis ATCC 29212. Material y Método: El estudio fue longitudinal, comparativo y experimental; cada aceite esencial estuvo conformado por 3 repeticiones para el ensayo de espectrofotometría la muestra fue de 152 tubos y para el ensayo de difusión fue de 24 placas. Para determinar la eficacia atimicrobiana de cada aceite esencial se decidió usar 7 diferentes concentraciones : 100%, 50%, 25%, 12,5%, 6,25%, 3,13% y 1,56% además del grupo control ( Agua destilada + hidróxido de calcio). Para la comparación del efecto se aplicaron las pruebas estadísticas Anova y Duncan. Resultado: El efecto antimicrobiano de las combinaciones de los aceites esenciales con CaOH 2 a traves de los dos metódos se observó que por espectrofotometría las concentraciones mas resaltantes fueron al 100 % (0.73 nm), 25%( 0.95nm) y 3,13% (1.60 nm) del aceite de Matricaria chamomilla. Y por el método de difusión, según Duncan las concentraciones ubicadas en el primer grupo fueron: al 100% (1.43 mm) del aceite de Curcuma longa, al 100% (1,67 mm) del aceite de Matricaria chamomilla y el grupo control (CaOH 2 + agua destilada) (1.53 mm). Conclusión: El aceite esencial de Matricaria chamomilla al combinado con hidróxido de calcio fue la más eficaz .To compare the in vitro antimicrobial effect of the essential oil of Matricaria chamomilla and Curcuma longa embedded with CaOH2 against Enterococcus faecalis ATCC 29212. Material and Method: The study was longitudinal, comparative and experimental; each essential oil consisted of 3 repetitions for the spectrophotometry test the sample was 152 tubes and for the diffusion test was 24 plates. To determine the atimicrobial efficacy of each essential oil, it was decided to use 7 different concentrations: 100%, 50%, 25%, 12.5%, 6.25%, 3.13% and 1.56% in addition to the control group (Water distilled + calcium hydroxide). For the comparison of the effect, the Anova and Duncan statistical tests were applied. Result: The antimicrobial effect of the combinations of essential oils with CaOH2 through the two methods showed that by spectrophotometry the most outstanding concentrations were 100% (0.73 nm), 25% (0.95nm) and 3.13% ( 1.60 nm) of Matricaria chamomilla oil. And by the diffusion method, according to Duncan, the concentrations located in the first group were: 100% (1.43 mm) of the Curcuma longa oil, 100% (1.67 mm) of the Matricaria chamomilla oil and the control group ( CaOH2 + distilled water) (1.53 mm). Conclusion: The essential oil of Matricaria chamomilla when combined with calcium hydroxide was the most effectiveTesi