Análisis de elementos viga-columna en régimen no lineal con deformación por cortante

El hormigón estructural sigue siendo sin duda uno de los materiales más utilizados en construcción debido a su resistencia, rigidez y flexibilidad para diseñar estructuras. El cálculo de estructuras de hormigón, utilizando vigas y vigas-columna, es complejo debido a los fenómenos de acoplamiento entre esfuerzos y al comportamiento no lineal del material. Los modelos más empleados para su análisis son el de Bernoulli-Euler y el de Timoshenko, indicándose en la literatura la conveniencia de usar el segundo cuando la relación canto/luz no es pequeña o los elementos están fuertemente armados. El objetivo fundamental de esta tesis es el análisis de elementos viga y viga-columna en régimen no lineal con deformación por cortante, aplicando el concepto de Pieza Lineal Equivalente (PLE). Concepto éste que consiste básicamente en resolver el problema de una pieza en régimen no lineal, transformándolo en uno lineal equivalente, de modo que ambas piezas tengan la misma deformada y los mismos esfuerzos. Para ello, se hizo en primer lugar un estudio comparado de: las distintas propuestas que aplican la deformación por cortante, de los distintos modelos constitutivos y seccionales del hormigón estructural y de los métodos de cálculo no lineal aplicando el método de elementos finitos (MEF). Teniendo en cuenta que la resolución del problema no lineal se basa en la resolución de sucesivos problemas lineales empleando un proceso de homotopía, los problemas lineales de la viga y viga-columna de Timoshenko, se resuelven mediante MEF, utilizando soluciones nodalmente exactas (SNE) y acción repartida equivalente de cualquier orden. Se obtiene así, con muy pocos elementos finitos, una excelente aproximación de la solución, no sólo en los nodos sino en el interior de los elementos. Se introduce el concepto PLE para el análisis de una barra, de material no lineal, sometida a acciones axiales, y se extiende el mismo para el análisis no lineal de vigas y vigas-columna con deformación por cortante. Cabe señalar que para estos últimos, la solución de una pieza en régimen no lineal es igual a la de una en régimen lineal, cuyas rigideces son constantes a trozos, y donde además hay que añadir momentos y cargas puntuales ficticias en los nodos, así como, un momento distribuido ficticio en toda la pieza. Se han desarrollado dos métodos para el análisis: uno para problemas isostáticos y otro general, aplicable tanto a problemas isostáticos como hiperestáticos. El primero determina de entrada la PLE, realizándose a continuación el cálculo por MEF-SNE de dicha pieza, que ahora está en régimen lineal. El general utiliza una homotopía que transforma de manera iterativa, unas leyes constitutivas lineales en las leyes no lineales del material. Cuando se combina con el MEF, la pieza lineal equivalente y la solución del problema original quedan determinadas al final de todo el proceso. Si bien el método general es un procedimiento próximo al de Newton- Raphson, presenta sobre éste la ventaja de permitir visualizar las deformaciones de la pieza en régimen no lineal, de manera tanto cualitativa como cuantitativa, ya que es posible observar en cada paso del proceso la modificación de rigideces (a flexión y cortante) y asimismo la evolución de las acciones ficticias. Por otra parte, los resultados obtenidos comparados con los publicados en la literatura, indican que el concepto PLE ofrece una forma directa y eficiente para analizar con muy buena precisión los problemas asociados a vigas y vigas-columna en las que por su tipología los efectos del cortante no pueden ser despreciados. ABSTRACT The structural concrete clearly remains the most used material in construction due to its strength, rigidity and structural design flexibility. The calculation of concrete structures using beams and beam-column is complex as consequence of the coupling phenomena between stresses and of its nonlinear behaviour. The models most commonly used for analysis are the Bernoulli-Euler and Timoshenko. The second model is strongly recommended when the relationship thickness/span is not small or in case the elements are heavily reinforced. The main objective of this thesis is to analyse the beam and beam-column elements with shear deformation in nonlinear regime, applying the concept of Equivalent Linear Structural Element (ELSE). This concept is basically to solve the problem of a structural element in nonlinear regime, transforming it into an equivalent linear structural element, so that both elements have the same deformations and the same stresses. Firstly, a comparative study of the various proposals of applying shear deformation, of various constitutive and sectional models of structural concrete, and of the nonlinear calculation methods (using finite element methods) was carried out. Considering that the resolution of nonlinear problem is based on solving the successive linear problem, using homotopy process, the linear problem of Timoshenko beam and beam-columns is resolved by FEM, using the exact nodal solutions (ENS) and equivalent distributed load of any order. Thus, the accurate solution approximation can be obtained with very few finite elements for not only nodes, but also for inside of elements. The concept ELSE is introduced to analyse a bar of nonlinear material, subjected to axial forces. The same bar is then used for other nonlinear beam and beam-column analysis with shear deformation. It is noted that, for the last analyses, the solution of a structural element in nonlinear regime is equal to that of linear regime, in which the piecewise-stiffness is constant, the moments and fictitious point loads need to be added at nodes of each element, as well as the fictitious distributed moment on element. Two methods have been developed for analysis: one for isostatic problem and other more general, applicable for both isostatic and hiperstatic problem. The first method determines the ELSE, and then the calculation of this piece is performed by FEM-ENS that now is in linear regime. The general method uses the homotopy that transforms iteratively linear constitutive laws into nonlinear laws of material. When combined with FEM, the ELSE and the solution of the original problem are determined at the end of the whole process. The general method is well known as a procedure closed to Newton-Raphson procedure but presents an advantage that allows displaying deformations of the piece in nonlinear regime, in both qualitative and quantitative way. Since it is possible to observe the modification of stiffness (flexural and shear) in each step of process and also the evolution of the fictitious actions. Moreover, the results compared with those published in the literature indicate that the ELSE concept offers a direct and efficient way to analyze with very good accuracy the problems associated with beams and beams columns in which, by typology, the effects of shear cannot be neglected.

Optimización de cimentaciones directas de medianería y esquina mediante modelos de elementos finitos

Existe un amplio catálogo de posibles soluciones para resolver la problemática de las zapatas de medianería así como, por extensión, las zapatas de esquina como caso particular de las anteriores. De ellas, las más habitualmente empleadas en estructuras de edificación son, por un lado, la utilización de una viga centradora que conecta la zapata de medianería con la zapata del pilar interior más próximo y, por otro, la colaboración de la viga de la primera planta trabajando como tirante. En la primera solución planteada, el equilibrio de la zapata de medianería y el centrado de la respuesta del terreno se consigue gracias a la colaboración del pilar interior con su cimentación y al trabajo a flexión de la viga centradora. La modelización clásica considera que se logra un centrado total de la reacción del terreno, con distribución uniforme de las tensiones de contacto bajo ambas zapatas. Este planteamiento presupone, por tanto, que la viga centradora logra evitar cualquier giro de la zapata de medianería y que el pilar puede, por ello, considerarse perfectamente empotrado en la cimentación. En este primer modelo, el protagonismo fundamental recae en la viga centradora, cuyo trabajo a flexión conduce frecuentemente a unas escuadrías y a unas cuantías de armado considerables. La segunda solución, plantea la colaboración de la viga de la primera planta, trabajando como tirante. De nuevo, los métodos convencionales suponen un éxito total en el mecanismo estabilizador del tirante, que logra evitar cualquier giro de la zapata de medianería, dando lugar a una distribución de tensiones también uniforme. Los modelos convencionales existentes para el cálculo de este tipo de cimentaciones presentan, por tanto, una serie de simplificaciones que permiten el cálculo de las mismas, por medios manuales, en un tiempo razonable, pero presentan el inconveniente de su posible alejamiento del comportamiento real de la cimentación, con las consecuencias negativas que ello puede suponer en el dimensionamiento de estos elementos estructurales. La presente tesis doctoral desarrolla un contraste de los modelos convencionales de cálculo de cimentaciones de medianería y esquina, mediante un análisis alternativo con modelos de elementos finitos, con el objetivo de poner de manifiesto las diferencias entre los resultados obtenidos con ambos tipos de modelización, analizar cuáles son las variables que más influyen en el comportamiento real de este tipo de cimentaciones y proponer un nuevo modelo de cálculo, de tipo convencional, más ajustado a la realidad. El proceso de investigación se desarrolla mediante una etapa experimental virtual que utiliza como modelo un pórtico tipo de edificación, ortogonal, de hormigón armado, con dos vanos y número variable de plantas. Tras identificar el posible giro de la cimentación como elemento clave en el comportamiento de las zapatas de medianería y de esquina, se adoptan como variables de estudio aquellas que mayor influencia puedan tener sobre el citado giro de las zapatas y sobre la rigidez del conjunto del elemento estructural. Así, se han estudiado luces de 3 m a 7 m, diferente número de plantas desde baja+1 hasta baja+4, resistencias del terreno desde 100 kN/m2 hasta 300 kN/m2, relaciones de forma de la zapata de medianería de 1,5 : 1 y 2 : 1, aumento y reducción de la cuantía de armado de la viga centradora y variación del canto de la viga centradora desde el mínimo canto compatible con el anclaje de la armadura de los pilares hasta un incremento del 75% respecto del citado canto mínimo. El conjunto de pórticos generados al aplicar las variables indicadas, se ha calculado tanto por métodos convencionales como por el método de los elementos finitos. Los resultados obtenidos ponen de manifiesto importantes discrepancias entre ambos métodos que conducen a importantes diferencias en el dimensionamiento de este tipo de cimentaciones. El empleo de los métodos tradicionales da lugar, por un lado, a un sobredimensionamiento de la armadura de la viga centradora y, por otro, a un infradimensionamiento, tanto del canto de la viga centradora, como del tamaño de la zapata de medianería y del armado de la viga de la primera planta. Finalizado el análisis y discusión de resultados, la tesis propone un nuevo método alternativo, de carácter convencional y, por tanto, aplicable a un cálculo manual en un tiempo razonable, que permite obtener los parámetros clave que regulan el comportamiento de las zapatas de medianería y esquina, conduciendo a un dimensionamiento más ajustado a las necesidades reales de este tipo de cimentación. There is a wide catalogue of possible solutions to solve the problem of party shoes and, by extension, corner shoes as a special case of the above. From all of them, the most commonly used in building structures are, on one hand, the use of a centering beam that connects the party shoe with the shoe of the nearest interior pillar and, on the other hand, the collaboration of the beam of the first floor working as a tie rod. In the first proposed solution, the balance of the party shoe and the centering of the ground response is achieved thanks to the collaboration of the interior pillar with his foundation along with the bending work of the centering beam. Classical modeling considers that a whole centering of the ground reaction is achieved, with uniform contact stress distribution under both shoes. This approach to the issue presupposes that the centering beam manages to avoid any rotation of the party shoe, so the pillar can be considered perfectly embedded in the foundation. In this first model, the leading role lies in the centering beam, whose bending work usually leads to important section sizes and high amounts of reinforced. The second solution, consideres the collaboration of the beam of the first floor, working as tie rod. Again, conventional methods involve a total success in the stabilizing mechanism of the tie rod, that manages to avoid any rotation of the party shoe, resulting in a stress distribution also uniform. Existing conventional models for calculating such foundations show, therefore, a series of simplifications which allow calculation of the same, by manual means, in a reasonable time, but have the disadvantage of the possible distance from the real behavior of the foundation, with the negative consequences this could bring in the dimensioning of these structural elements. The present thesis develops a contrast of conventional models of calculation of party and corner foundations by an alternative analysis with finite element models with the aim of bring to light the differences between the results obtained with both types of modeling, analysis which are the variables that influence the real behavior of this type of foundations and propose a new calculation model, conventional type, more adjusted to reality. The research process is developed through a virtual experimental stage using as a model a typical building frame, orthogonal, made of reinforced concrete, with two openings and variable number of floors. After identifying the possible spin of the foundation as the key element in the behavior of the party and corner shoes, it has been adopted as study variables, those that may have greater influence on the spin of the shoes and on the rigidity of the whole structural element. So, it have been studied lights from 3 m to 7 m, different number of floors from lower floor + 1 to lower floor + 4, máximum ground stresses from 100 kN/m2 300 kN/m2, shape relationships of party shoe 1,5:1 and 2:1, increase and decrease of the amount of reinforced of the centering beam and variation of the height of the centering beam from the minimum compatible with the anchoring of the reinforcement of pillars to an increase of 75% from the minimum quoted height. The set of frames generated by applying the indicated variables, is calculated both by conventional methods such as by the finite element method. The results show significant discrepancies between the two methods that lead to significant differences in the dimensioning of this type of foundation. The use of traditional methods results, on one hand, to an overdimensioning of the reinforced of the centering beam and, on the other hand, to an underdimensioning, both the height of the centering beam, such as the size of the party shoe and the reinforced of the beam of the first floor. After the analysis and discussion of results, the thesis proposes a new alternative method, conventional type and, therefore, applicable to a manual calculation in a reasonable time, that allows to obtain the key parameters that govern the behavior of party and corner shoes, leading to a dimensioning more adjusted to the real needings of this type of foundation.

Análisis paramétrico determinista y aleatorio de problemas dinámicos en estructuras aeroespaciales

Los fenómenos dinámicos pueden poner en peligro la integridad de estructuras aeroespaciales y los ingenieros han desarrollado diferentes estrategias para analizarlos. Uno de los grandes problemas que se plantean en la ingeniería es cómo atacar un problema dinámico estructural. En la presente tesis se plantean distintos fenómenos dinámicos y se proponen métodos para estimar o simular sus comportamientos mediante un análisis paramétrico determinista y aleatorio del problema. Se han propuesto desde problemas sencillos con pocos grados de libertad que sirven para analizar las diferentes estrategias y herramientas a utilizar, hasta fenómenos muy dinámicos que contienen comportamientos no lineales, daños y fallos. Los primeros ejemplos de investigación planteados cubren una amplia gama de los fenómenos dinámicos, como el análisis de vibraciones de elementos másicos, incluyendo impactos y contactos, y el análisis de una viga con carga armónica aplicada a la que también se le añaden parámetros aleatorios que pueden responder a un desconocimiento o incertidumbre de los mismos. Durante el desarrollo de la tesis se introducen conceptos y se aplican distintos métodos, como el método de elementos finitos (FEM) en el que se analiza su resolución tanto por esquemas implícitos como explícitos, y métodos de análisis paramétricos y estadísticos mediante la técnica de Monte Carlo. Más adelante, una vez ya planteadas las herramientas y estrategias de análisis, se estudian fenómenos más complejos, como el impacto a baja velocidad en materiales compuestos, en el que se busca evaluar la resistencia residual y, por lo tanto, la tolerancia al daño de la estructura. Se trata de un suceso que puede producirse por la caída de herramienta, granizo o restos en la pista de aterrizaje. Otro de los fenómenos analizados también se da en un aeropuerto y se trata de la colisión con un dispositivo frangible, el cual tiene que romperse bajo ciertas cargas y, sin embargo, soportar otras. Finalmente, se aplica toda la metodología planteada en simular y analizar un posible incidente en vuelo, el fenómeno de la pérdida de pala de un turbohélice. Se trata de un suceso muy particular en el que la estructura tiene que soportar unas cargas complejas y excepcionales con las que la aeronave debe ser capaz de completar con éxito el vuelo. El análisis incluye comportamientos no lineales, daños, y varios tipos de fallos, y en el que se trata de identificar los parámetros clave en la secuencia del fallo. El suceso se analiza mediante análisis estructurales deterministas más habituales y también mediante otras técnicas como el método de Monte Carlo con el que se logran estudiar distintas incertidumbres en los parámetros con variables aleatorias. Se estudian, entre otros, el tamaño de pala perdida, la velocidad y el momento en el que se produce la rotura, y la rigidez y resistencia de los apoyos del motor. Se tiene en cuenta incluso el amortiguamiento estructural del sistema. Las distintas estrategias de análisis permiten obtener unos resultados valiosos e interesantes que han sido objeto de distintas publicaciones. ABSTRACT Dynamic phenomena can endanger the integrity of aerospace structures and, consequently, engineers have developed different strategies to analyze them. One of the major engineering problems is how to deal with the structural dynamics. In this thesis, different dynamic phenomena are introduced and several methods are proposed to estimate or simulate their behaviors. The analysis is considered through parametric, deterministic and statistical methods. The suggested issues are from simple problems with few degrees of freedom, in order to develop different strategies and tools to solve them, to very dynamic phenomena containing nonlinear behaviors failures, damages. The first examples cover a wide variety of dynamic phenomena such as vibration analysis of mass elements, including impacts and contacts, and beam analysis with harmonic load applied, in which random parameters are included. These parameters can represent the unawareness or uncertainty of certain variables. During the development of the thesis several concepts are introduced and different methods are applied, such as the finite element method (FEM), which is solved through implicit and explicit schemes, and parametrical and statistical methods using the Monte Carlo analysis technique. Next, once the tools and strategies of analysis are set out more complex phenomena are studied. This is the case of a low-speed impact in composite materials, the residual strength of the structure is evaluated, and therefore, its damage tolerance. This incident may occur from a tool dropped, hail or debris throw on the runway. At an airport may also occur, and it is also analyzed, a collision between an airplane and a frangible device. The devise must brake under these loads, however, it must withstand others. Finally, all the considered methodology is applied to simulate and analyze a flight incident, the blade loss phenomenon of a turboprop. In this particular event the structure must support complex and exceptional loads and the aircraft must be able to successfully complete the flight. Nonlinear behavior, damage, and different types of failures are included in the analysis, in which the key parameters in the failure sequence are identified. The incident is analyzed by deterministic structural analysis and also by other techniques such as Monte Carlo method, in which it is possible to include different parametric uncertainties through random variables. Some of the evaluated parameters are, among others, the blade loss size, propeller rotational frequency, speed and angular position where the blade is lost, and the stiffness and strength of the engine mounts. The study does also research on the structural damping of the system. The different strategies of analysis obtain valuable and interesting results that have been already published.

Monumentalidad y Arquitectura. Tres consideraciones críticas: lo escrito, lo proyectado y lo construido durante el periodo moderno

El origen de esta tesis considera una lectura (quizás) pendiente: definir críticamente a la monumentalidad en el contexto de la arquitectura moderna. La idea de lo monumental durante la modernidad establece parte de la negación enmarcada en un planteamiento más amplio, basado en el rechazo a todo vínculo con la tradición y la historia. Desde el estatismo del monumento como objeto anacrónico, a la instrumentación de la arquitectura como herramienta simbólica, el proceso transformador más importante para la arquitectura durante el siglo XX contaba con algunas señales que nos daban la pauta para imaginar una realidad conformada por matices y desacuerdos fundamentales. La investigación no pretende contar una nueva historia sobre el periodo moderno, aunque irremediablemente se vale de su registro para presentar la discusión. Así, la idea crítica que sostenemos tiene que ver con las posibilidades estructurales y objetivas del discurso arquitectónico. Un discurso que se analiza en función de tres campos diferenciados, designados como: lo escrito, lo proyectado y lo construido en el periodo de estudio. De esta manera, pensamos que se favorecen las posibilidades dimensionales de la crítica y se amplía el sentido narrativo de la linealidad histórica. Para esta trabajo, la monumentalidad constituye una sustancia de estudio que evidencia las contradicciones, inadvertencias y matices necesarios en la articulación de una visión más compleja sobre los acontecimientos. Convencidos de la eficacia de un modelo dialéctico, que define la condición de lo monumental tanto en una valoración positiva (lo propicio, lo útil, lo verdadero, etc.) como negativa (lo falso, lo ostentoso, lo altisonante, etc.); observaremos que las diferencias alrededor del concepto derivan respectivamente en los significados de monumentalidad y monumentalismo. El contraste y la oposición de ideas expuestas a la luz favorece esa pretensión dimensional de la crítica. De los escritos de Sigfried Giedion -y la Nueva Monumentalidad- a Le Corbusier y la construcción de Chandigarh; o de la crítica anti-monumental de Karel Teige, pasando por el proyecto constructivista de Ivan Leonidov; los distintos episodios referidos en el trabajo encuentran sentido y rechazan las probabilidades arbitrarias y confusas de la selección temática. En ese orden, se busca asignar cierto rigor metodológico e incluso geométrico: la estructura propuesta toma el gran "periodo moderno" en dos bloques temporales, primera-modernidad (alrededor de 1910-1935) y tardo-modernidad (aprox. 1935-1960). En la primera parte se analizan una postura -en mayor medida- reactiva a las manifestaciones de esa hipotética condición monumental, mientras que en el segundo caso la postura se transforma y se perfila un nuevo escenario que anticipará ideológicamente parte de la evidente fractura posmoderna. A su vez, los tres registros anunciados previamente se componen de dos capítulos en función del marco temporal descrito; cada capítulo se desarrolla en tres partes que abundan en los aspectos preliminares de la discusión, luego exponen unos puntos centrales y finalmente orientan un posible recuento. El trabajo se complementa con una parte introductoria que fluye sobre definiciones concretas del monumento, el monumentalismo y la monumentalidad; además de que definirá la orientación de la crítica desarrollada. En una última intervención, a manera de conclusión, se reflexiona sobre el salto temporal, ideológico y estético que la posmodernidad representó para el tema de investigación.   Abstract The purpose of this thesis is to consider a (perhaps) pendant issue: to define monumentality by means of critical approach within the modern context of architecture. The idea of what monumental is during modernity establishes a fraction of the "modern typical denial" based on the rejection of any link to tradition and history. From the anachronistic idea of static monuments, to the orchestration of architecture as a symbolic tool, the most important process of the revolution of architecture during the 20th Century had a few signs that allowed us to imagine a reality conformed by fundamental nuances and disagreements. The aim of this research is not to tell a new story about the modern period, although inexorable it takes note of the register to present the discussion. Therefore, the idea of what we expose as criticism has to do with structural and objective possibilities in the architectural discourse. A speech analyzed in response to three differentiated domains designated here as: the written, the projected and the built during the selected time. In that way, we believe the dimensional possibilities of criticism are favored and the narrative sense of historical process is expanded. In terms of this investigation monumentality constitutes a matter of study that leads us to contradictions, unnoticed issues and necessary gray areas in the articulation of a complex vision about depicted events. We are convinced in the efficiency of a dialectical analysis model in order to define the monumental condition both as a positive value (propitious, useful, truthful, etc.) and a negative one (untrue, ostentatious, pompous, etc.); the idea is to show the differences around respective meanings deriving in terms of monumentality and monumentalism. Contrasting information and the opposition of ideas exposed in this light helped to develop the assumption of dimensional criticism. From Sigfried Giedeon's writings -and the New Monumentality- to Le Corbusier and the construction of Chandigarh; and from Karel Teige's anti-monumental criticism going through the revision of Ivan Leonidov's constructivist project; the variety of episodes referred to this work find some sense and reject the probabilities about confusion and arbitrary in the selection of themes. In order to assign some methodological precision and even geometrical criterion, the proposed structure divides the "great modern time" into two historical blocks: first-modernity (circa 1910-1935) and late-modernity (around 1935-1960). The first part analyzes a -mainly- reactive stance towards the hypothetical expressions of monumental condition, whereas in the second block the rejection tends to be transformed and to project a new scenario that will foresee the ideological postmodern fracture. At the same time, the three registers are composed by two chapters each one will operate depending on the described time frame. Each chapter is organized in three subsequent parts: at first explaining preliminary ideas for discussion, second presenting central points and finally orienting a partial recount. The research is complemented with an introductory episode describing specific definitions concerning the concepts of monument, monumentalism and monumentality; and mainly orienting the developed critique. In a final intervention, as a way of conclusion, we reflect on ideological and aesthetic qualities that postmodern time shift represented for this investigation.

Application of the dynamic models to the detection of imperfections in plate Structures

This paper is part of a set of publications related with the development of mathematical models aimed to simulate the dynamic input and output of experimental nondestructive tests in order to detect structural imperfections. The structures to be considered are composed by steel plates of thin thickness. The imperfections in these cases are cracks and they can penetrate either a significant part of the plate thickness or be micro cracks or superficial imperfections. The first class of cracks is related with structural safety and the second one is more connected to the structural protection to the environment, particularly if protective paintings can be deteriorated. Two mathematical groups of models have been developed. The first group tries to locate the position and extension of the imperfection of the first class of imperfections, i.e. cracks and it is the object of the present paper. Bending Kirchoff thin plate models belong to this first group and they are used to this respect. The another group of models is dealt with membrane structures under the superficial Rayleigh waves excitation. With this group of models the micro cracks detection is intended. In the application of the first group of models to the detection of cracks, it has been observed that the differences between the natural frequencies of the non cracked and the cracked structures are very small. However, geometry and crack position can be identified quite accurately if this comparison is carried out between first derivatives (mode rotations) of the natural modes are used instead. Finally, in relation with the analysis of the superficial crack existence the use of Rayleigh waves is very promising. The geometry and the penetration of the micro crack can be detected very accurately. The mathematical and numerical treatment of the generation of these Rayleigh waves present and a numerical application has been shown.

A INFLUÊNCIA DAS PRÁTICAS PEDAGÓGICAS DOCENTES E DAS BARREIRAS DISCENTES SOBRE O DESENVOLVIMENTO DA CRIATIVIDADE DO FUTURO ADMINISTRADOR

As empresas que almejam garantir e melhorar sua posição dentro de em um mercado cada vez mais competitivo precisam estar sempre atualizadas e em constante evolução. Na busca contínua por essa evolução, investem em projetos de Pesquisa & Desenvolvimento (P&D) e em seu capital humano para promover a criatividade e a inovação organizacional. As pessoas têm papel fundamental no desenvolvimento da inovação, mas para que isso possa florescer de forma constante é preciso comprometimento e criatividade para a geração de ideias. Criatividade é pensar o novo; inovação é fazer acontecer. Porém, encontrar pessoas com essas qualidades nem sempre é tarefa fácil e muitas vezes é preciso estimular essas habilidades e características para que se tornem efetivamente criativas. Os cursos de graduação podem ser uma importante ferramenta para trabalhar esses aspectos, características e habilidades, usando métodos e práticas de ensino que auxiliem no desenvolvimento da criatividade, pois o ambiente ensino-aprendizagem pesa significativamente na formação das pessoas. O objetivo deste estudo é de identificar quais fatores têm maior influência sobre o desenvolvimento da criatividade em um curso de graduação em administração, analisando a influência das práticas pedagógicas dos docentes e as barreiras internas dos discentes. O referencial teórico se baseia principalmente nos trabalhos de Alencar, Fleith, Torrance e Wechsler. A pesquisa transversal de abordagem quantitativa teve como público-alvo os alunos do curso de Administração de uma universidade confessional da Grande São Paulo, que responderam 465 questionários compostos de três escalas. Para as práticas docentes foi adaptada a escala de Práticas Docentes em relação à Criatividade. Para as barreiras internas foi adaptada a escala de Barreiras da Criatividade Pessoal. Para a análise da percepção do desenvolvimento da criatividade foi construída e validada uma escala baseada no referencial de características de uma pessoa criativa. As análises estatísticas descritivas e fatoriais exploratórias foram realizadas no software Statistical Package for the Social Sciences (SPSS), enquanto as análises fatoriais confirmatórias e a mensuração da influência das práticas pedagógicas e das barreiras internas sobre a percepção do desenvolvimento da criatividade foram realizadas por modelagem de equação estrutural utilizando o algoritmo Partial Least Squares (PLS), no software Smart PLS 2.0. Os resultados apontaram que as práticas pedagógicas e as barreiras internas dos discentes explicam 40% da percepção de desenvolvimento da criatividade, sendo as práticas pedagógicas que exercem maior influencia. A pesquisa também apontou que o tipo de temática e o período em que o aluno está cursando não têm influência sobre nenhum dos três construtos, somente o professor influencia as práticas pedagógicas.

ANALISANDO A RELAÇÃO DOS VOLUMES DE EXPORTAÇÃO E DE IMPORTAÇÃO, PIB, TAXAS DE CÂMBIO E INFLAÇÃO NO PERÍODO DE 2004 A 2014.

Esta dissertação visa deslumbrar uma análise macroeconômica do Brasil, especialmente no que se refere à relação dos índices mensais dos volumes das exportações e das importações com os volumes mensais do PIB, da Taxa SELIC e as Taxas de Câmbio, conforme dados coletados no período de janeiro de 2004 a dezembro de 2014, através de pesquisa literária referente aos históricos sobre cada conceito envolvido no âmbito da macroeconomia das varáveis estudadas. Foi realizado um estudo de caso embasado em dados de sites governamentais, no período delimitado, empregando-se o método de regressão linear, com base na Teoria da correlação de Pearson, demonstrando os resultados obtidos no período do estudo para as varáveis estudadas. Desta maneira, conseguiu-se estudar e analisar como as variáveis dependentes (resposta): volume das exportações e volume das importações estão relacionadas com as varáveis independentes (explicativas): PIB, Taxa Selic e taxa de Câmbio. Os resultados apurados no presente estudo permitem identificar que existe correlação moderada e negativa, quando analisadas a Taxa Selic e a Taxa de Câmbio com os volumes das exportações e das importações, enquanto o PIB apresenta correlação forte e positiva na análise com os volumes das exportações e das importações

GESTÃO DO CONHECIMENTO: UM ESTUDO SOBRE A RELAÇÃO ENTRE A LIDERANÇA TRANSFORMACIONAL, A CONVERSÃO DO CONHECIMENTO E A EFICÁCIA ORGANIZACIONAL

Este estudo teve como objetivo principal analisar a relação entre a Liderança Transformacional, a Conversão do Conhecimento e a Eficácia Organizacional. Foram considerados como pressupostos teóricos conceitos consolidados sobre os temas desta relação, além de recentes pesquisas já realizadas em outros países e contextos organizacionais. Com base nisto identificou-se potencial estudo de um modelo que relacionasse estes três conceitos. Para tal considera-se que as organizações que buscam atingir Vantagem Competitiva e incorporam a Knowledge-Based View possam conquistar diferenciação frente a seus concorrentes. Nesse contexto o conhecimento ganha maior destaque e papel protagonista nestas organizações. Dessa forma criar conhecimento através de seus colaboradores, passa a ser um dos desafios dessas organizações ao passo que sugere melhoria de seus indicadores Econômicos, Sociais, Sistêmicos e Políticos, o que se define por Eficácia Organizacional. Portanto os modos de conversão do conhecimento nas organizações, demonstram relevância, uma vez que se cria e se converte conhecimentos através da interação entre o conhecimento existente de seus colaboradores. Essa conversão do conhecimento ou modelo SECI possui quatro modos que são a Socialização, Externalização, Combinação e Internalização. Nessa perspectiva a liderança nas organizações apresenta-se como um elemento capaz de influenciar seus colaboradores, propiciando maior dinâmica ao modelo SECI de conversão do conhecimento. Se identifica então na liderança do tipo Transformacional, características que possam influenciar colaboradores e entende-se que esta relação entre a Liderança Transformacional e a Conversão do Conhecimento possa ter influência positiva nos indicadores da Eficácia Organizacional. Dessa forma esta pesquisa buscou analisar um modelo que explorasse essa relação entre a liderança do tipo Transformacional, a Conversão do Conhecimento (SECI) e a Eficácia Organizacional. Esta pesquisa teve o caráter quantitativo com coleta de dados através do método survey, obtendo um total de 230 respondentes válidos de diferentes organizações. O instrumento de coleta de dados foi composto por afirmativas relativas ao modelo de relação pesquisado com um total de 44 itens. O perfil de respondentes concentrou-se entre 30 e 39 anos de idade, com a predominância de organizações privadas e de departamentos de TI/Telecom, Docência e Recursos Humanos respectivamente. O tratamento dos dados foi através da Análise Fatorial Exploratória e Modelagem de Equações Estruturais via Partial Least Square Path Modeling (PLS-PM). Como resultado da análise desta pesquisa, as hipóteses puderam ser confirmadas, concluindo que a Liderança Transformacional apresenta influência positiva nos modos de Conversão do Conhecimento e que; a Conversão do Conhecimento influencia positivamente na Eficácia Organizacional. Ainda, concluiu-se que a percepção entre os respondentes não apresenta resultado diferente sobre o modelo desta pesquisa entre quem possui ou não função de liderança.

Whole genome analysis: Experimental access to all genome sequenced segments through larger-scale efficient oligonucleotide synthesis and PCR

The recent ability to sequence whole genomes allows ready access to all genetic material. The approaches outlined here allow automated analysis of sequence for the synthesis of optimal primers in an automated multiplex oligonucleotide synthesizer (AMOS). The efficiency is such that all ORFs for an organism can be amplified by PCR. The resulting amplicons can be used directly in the construction of DNA arrays or can be cloned for a large variety of functional analyses. These tools allow a replacement of single-gene analysis with a highly efficient whole-genome analysis.

CLARP, a death effector domain-containing protein interacts with caspase-8 and regulates apoptosis

We have identified and characterized CLARP, a caspase-like apoptosis-regulatory protein. Sequence analysis revealed that human CLARP contains two amino-terminal death effector domains fused to a carboxyl-terminal caspase-like domain. The structure and amino acid sequence of CLARP resemble those of caspase-8, caspase-10, and DCP2, a Drosophila melanogaster protein identified in this study. Unlike caspase-8, caspase-10, and DCP2, however, two important residues predicted to be involved in catalysis were lost in the caspase-like domain of CLARP. Analysis with fluorogenic substrates for caspase activity confirmed that CLARP is catalytically inactive. CLARP was found to interact with caspase-8 but not with FADD/MORT-1, an upstream death effector domain-containing protein of the Fas and tumor necrosis factor receptor 1 signaling pathway. Expression of CLARP induced apoptosis, which was blocked by the viral caspase inhibitor p35, dominant negative mutant caspase-8, and the synthetic caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-(OMe)-fluoromethylketone (zVAD-fmk). Moreover, CLARP augmented the killing ability of caspase-8 and FADD/MORT-1 in mammalian cells. The human clarp gene maps to 2q33. Thus, CLARP represents a regulator of the upstream caspase-8, which may play a role in apoptosis during tissue development and homeostasis.

Controlled unzipping of a bacterial surface layer with atomic force microscopy

We have combined high-resolution atomic force microscopy (AFM) imaging and force spectroscopy to gain insight into the interaction forces between the individual protomers of the hexagonally packed intermediate (HPI) layer of Deinococcus radiodurans. After imaging the HPI layer, the AFM stylus was attached to individual protomers by enforced stylus-sample contact to allow force spectroscopy experiments. Imaging of the HPI layer after recording force-extension curves allowed adhesion forces to be correlated with structural alterations. By using this approach, individual protomers of the HPI layer were found to be removed at pulling forces of ≈300 pN. Furthermore, it was possible to sequentially unzip entire bacterial pores formed by six HPI protomers. The combination of high-resolution AFM imaging of individual proteins with the determination of their intramolecular forces is a method of studying the mechanical stability of supramolecular structures at the level of single molecules.

Memory and long-term potentiation (LTP) dissociated: Normal spatial memory despite CA1 LTP elimination with Kv1.4 antisense

Long-term potentiation (LTP) in the hippocampal slice preparation has been proposed as an in vitro model for long-term memory. However, correlation of LTP with memory in living animals has been difficult to demonstrate. Furthermore, in the last few years evidence has accumulated that dissociate the two. Because potassium channels might determine the weight of synapses in networks, we studied the role of Kv1.4, a presynaptic A-type voltage-dependent K+ channel, in both memory and LTP. Reverse transcription–PCR and Western blot analysis with specific antibodies showed that antisense oligodeoxyribonucleotide to Kv1.4 microinjected intraventricularly into rat brains obstructed hippocampal Kv1.4 mRNA, “knocking down” the protein in the hippocampus. This antisense knockdown had no effect on rat spatial maze learning, memory, or exploratory behavior, but eliminated both early- and late-phase LTP and reduced paired-pulse facilitation (a presynaptic effect) in CA1 pyramidal neurons without affecting dentate gyrus LTP. This presynaptic Kv1.4 knockdown together with previous postsynaptic Kv1.1 knockdown demonstrates that CA1 LTP is neither necessary nor sufficient for rat spatial memory.

The Mr 140,000 Intermediate Chain of Chlamydomonas Flagellar Inner Arm Dynein Is a WD-Repeat Protein Implicated in Dynein Arm Anchoring

Previous structural and biochemical studies have revealed that the inner arm dynein I1 is targeted and anchored to a unique site located proximal to the first radial spoke in each 96-nm axoneme repeat on flagellar doublet microtubules. To determine whether intermediate chains mediate the positioning and docking of dynein complexes, we cloned and characterized the 140-kDa intermediate chain (IC140) of the I1 complex. Sequence and secondary structural analysis, with particular emphasis on β-sheet organization, predicted that IC140 contains seven WD repeats. Reexamination of other members of the dynein intermediate chain family of WD proteins indicated that these polypeptides also bear seven WD/β-sheet repeats arranged in the same pattern along each intermediate chain protein. A polyclonal antibody was raised against a 53-kDa fusion protein derived from the C-terminal third of IC140. The antibody is highly specific for IC140 and does not bind to other dynein intermediate chains or proteins in Chlamydomonas flagella. Immunofluorescent microscopy of Chlamydomonas cells confirmed that IC140 is distributed along the length of both flagellar axonemes. In vitro reconstitution experiments demonstrated that the 53-kDa C-terminal fusion protein binds specifically to axonemes lacking the I1 complex. Chemical cross-linking indicated that IC140 is closely associated with a second intermediate chain in the I1 complex. These data suggest that IC140 contains domains responsible for the assembly and docking of the I1 complex to the doublet microtubule cargo.

Chromosomal instability and cytoskeletal defects in oral cancer cells

Oral squamous cell carcinomas are characterized by complex, often near-triploid karyotypes with structural and numerical variations superimposed on the initial clonal chromosomal alterations. We used immunohistochemistry combined with classical cytogenetic analysis and spectral karyotyping to investigate the chromosomal segregation defects in cultured oral squamous cell carcinoma cells. During division, these cells frequently exhibit lagging chromosomes at both metaphase and anaphase, suggesting defects in the mitotic apparatus or kinetochore. Dicentric anaphase chromatin bridges and structurally altered chromosomes with consistent long arms and variable short arms, as well as the presence of gene amplification, suggested the occurrence of breakage–fusion–bridge cycles. Some anaphase bridges were observed to persist into telophase, resulting in chromosomal exclusion from the reforming nucleus and micronucleus formation. Multipolar spindles were found to various degrees in the oral squamous cell carcinoma lines. In the multipolar spindles, the poles demonstrated different levels of chromosomal capture and alignment, indicating functional differences between the poles. Some spindle poles showed premature splitting of centrosomal material, a precursor to full separation of the microtubule organizing centers. These results indicate that some of the chromosomal instability observed within these cancer cells might be the result of cytoskeletal defects and breakage–fusion–bridge cycles.

Brain responses associated with consciousness of breathlessness (air hunger)

Little is known about the physiological mechanisms subserving the experience of air hunger and the affective control of breathing in humans. Acute hunger for air after inhalation of CO2 was studied in nine healthy volunteers with positron emission tomography. Subjective breathlessness was manipulated while end-tidal CO2- was held constant. Subjects experienced a significantly greater sense of air hunger breathing through a face mask than through a mouthpiece. The statistical contrast between the two conditions delineated a distributed network of primarily limbic/paralimbic brain regions, including multiple foci in dorsal anterior and middle cingulate gyrus, insula/claustrum, amygdala/periamygdala, lingual and middle temporal gyrus, hypothalamus, pulvinar, and midbrain. This pattern of activations was confirmed by a correlational analysis with breathlessness ratings. The commonality of regions of mesencephalon, diencephalon and limbic/paralimbic areas involved in primal emotions engendered by the basic vegetative systems including hunger for air, thirst, hunger, pain, micturition, and sleep, is discussed with particular reference to the cingulate gyrus. A theory that the phylogenetic origin of consciousness came from primal emotions engendered by immediate threat to the existence of the organism is discussed along with an alternative hypothesis by Edelman that primary awareness emerged with processes of ongoing perceptual categorization giving rise to a scene [Edelman, G. M. (1992) Bright Air, Brilliant Fire (Penguin, London)].