Modelagem do comportamento estrutural estático e dinâmico e avaliação de conforto humano de edifícios de concreto armado.

Nas últimas décadas, a partir do crescimento substancial da população das grandes cidades, a demanda por espaço para habitação tem crescido de maneira importante. Para atender a estas necessidades, edificações cada vez mais altas e mais esbeltas são projetadas e vãos cada vez maiores são utilizados. Novos materiais são criados e aprimorados para que seja extraído o máximo de desempenho com o menor custo. Deste modo, esta dissertação tem como objetivo o estudo do comportamento estrutural e avaliação de conforto humano de edifícios de concreto armado. Para tal, são considerados ao longo do estudo quatro projetos de edificações de concreto armado distintos, com alturas variando na faixa de 30m a 70m (11 a 24 pavimentos), submetidos às ações das cargas usuais de projeto atuantes sobre edifícios residenciais, além das cargas de vento. No que tange ao desenvolvimento dos modelos computacionais são empregadas técnicas usuais de discretização, via método dos elementos finitos, por meio do programa ANSYS. Inicialmente, a resposta estrutural estática (deslocamentos e esforços) e dinâmica (acelerações de pico) dos modelos é obtida e comparada com base nos valores limites propostos por normas e recomendações de projeto. A partir de análises qualitativas e quantitativas desenvolvidas sobre a resposta dos modelos em estudo o desempenho estrutural dos edifícios analisados é avaliado, no que diz respeito ao conforto humano.

Potential applications of shape memory alloys in seismic retrofitting of exterior RC beam-column joints

Shape memory alloys (SMAs) have the ability to undergo large deformations with minimum residual strain and also the extraordinary ability to undergo reversible hysteretic shape change known as the shape memory effect. The shape memory effect of these alloys can be utilised to develop a convenient way of actively confine concrete sections to improve their shear strength, flexural ductility and ultimate strain. Most of the previous work on active confinement of concrete using SMA has been carried out on circular sections. In this study retrofitting strategies for active confinement of non-circular sections have been proposed. The proposed schemes presented in this paper are conceived with an aim to seismically retrofit beam-column joints in non-seismically designed reinforced concrete buildings. SMAs are complex materials and their material behaviour depends on number of parameters. Depending upon the alloying elements, SMAs exhibit different behaviour in different conditions and are highly sensitive to variation in temperature, phase in which it is used, loading pattern, strain rate and pre-strain conditions. Therefore, a detailed discussion on the behaviour of SMAs under different thermo-mechanical conditions is presented first.

Shape Memory Alloy Features for Seismic Retrofitting of External RC Beam-Column Joint

Shape memory alloys (SMAs) have the ability to undergo large deformations with minimum residual strain and also the extraordinary ability to undergo reversible hysteretic shape change known as the shape memory effect. The shape memory effect of these alloys can be utilised to develop a convenient way of actively confining concrete sections to improve their shear strength, flexural ductility and ultimate strain capacity. Most of the previous work on active confinement of concrete using SMA has been carried out on circular sections. In this study retrofitting strategies for active confinement of non-circular sections have been proposed. The proposed schemes presented in this paper are conceived with an aim to seismically retrofit a beam-column joint in non-seismically designed reinforced concrete buildings.

The complex material behaviour of SMAs depends on number of parameters. Depending upon the alloying elements, SMAs exhibit different behaviour in different conditions and are highly sensitive to variation in temperature, phase in which it is used, loading pattern, strain rate and pre-strain conditions. Therefore, a detailed discussion on the behaviour of SMAs under different thermo-mechanical conditions is presented first in this paper.

Cyclic behaviour of RC elements with plain reinforcing bars

O comportamento cíclico das estruturas de betão armado é fortemente condicionado pelo mecanismo de aderência entre o betão e o aço. O escorregamento relativo entre os dois materiais, resultante da degradação progressiva da aderência em elementos solicitados por ações cíclicas, é uma causa frequente de danos graves e até do colapso de estruturas devido à ocorrência de sismos. Entre as estruturas existentes de betão armado que foram dimensionadas e construídas antes da entrada em vigor dos regulamentos sísmicos atuais, muitas foram construídas com armadura lisa, e portanto, possuem fracas propriedades de aderência. A informação disponível na literatura sobre o comportamento cíclico de elementos estruturais de betão armado com armadura lisa é reduzida e a influência das propriedades da aderência associadas a este tipo de armadura no comportamento cíclico das estruturas existentes não se encontra ainda devidamente estudada. O objectivo principal desta tese foi estudar a influência do escorregamento na resposta cíclica de elementos estruturais de betão armado com armadura lisa. Foram realizados ensaios cíclicos em elementos do tipo nó viga-pilar, construídos à escala real, representativos de ligações interiores em edifícios existentes sem pormenorização específica para resistir às ações sísmicas. Para comparação, foi realizado o ensaio de um nó construído com armadura nervurada. Foi ainda realizado o ensaio cíclico de uma viga de betão armado recolhida de uma estrutura antiga. Foram elaborados modelos numéricos não-lineares para simular a resposta dos elementos ensaiados, concentrando especial atenção no mecanismo do escorregamento. Os resultados obtidos no âmbito desta tese contribuem para o avanço do conhecimento sobre o comportamento cíclico de elementos estruturais de betão armado com armadura lisa. As análises numéricas realizadas comprovam a necessidade de incluir os efeitos do escorregamento na modelação numérica deste tipo de estruturas de forma a representar com rigor a sua resposta às ações cíclicas.

Estudo numérico e experimental sobre o comportamento dinâmico de um edifício

Dissertação para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização em Estruturas

Avaliação comparativa dos efeitos da introdução dos eurocódigos no cálculo sísmico de edifícios de betão armado

Dissertação de natureza Científica para obtenção do grau de Mestre na Área de Especialização de Estruturas

Caracterização dinâmica de um edifício existente de betão armado através de ensaios de vibração ambiental

Dissertação de natureza Científica para obtenção do grau de Mestre em Engenharia Civil

Modelos de elementos finitos explícitos para explosiones en estructuras reticuladas de hormigón armado : aplicaciones al estudio del colapso de edificios

La frecuencia con la que se producen explosiones sobre edificios, ya sean accidentales o intencionadas, es reducida, pero sus efectos pueden ser catastróficos. Es deseable poder predecir de forma suficientemente precisa las consecuencias de estas acciones dinámicas sobre edificaciones civiles, entre las cuales las estructuras reticuladas de hormigón armado son una tipología habitual. En esta tesis doctoral se exploran distintas opciones prácticas para el modelado y cálculo numérico por ordenador de estructuras de hormigón armado sometidas a explosiones. Se emplean modelos numéricos de elementos finitos con integración explícita en el tiempo, que demuestran su capacidad efectiva para simular los fenómenos físicos y estructurales de dinámica rápida y altamente no lineales que suceden, pudiendo predecir los daños ocasionados tanto por la propia explosión como por el posible colapso progresivo de la estructura. El trabajo se ha llevado a cabo empleando el código comercial de elementos finitos LS-DYNA (Hallquist, 2006), desarrollando en el mismo distintos tipos de modelos de cálculo que se pueden clasificar en dos tipos principales: 1) modelos basados en elementos finitos de continuo, en los que se discretiza directamente el medio continuo mediante grados de libertad nodales de desplazamientos; 2) modelos basados en elementos finitos estructurales, mediante vigas y láminas, que incluyen hipótesis cinemáticas para elementos lineales o superficiales. Estos modelos se desarrollan y discuten a varios niveles distintos: 1) a nivel del comportamiento de los materiales, 2) a nivel de la respuesta de elementos estructurales tales como columnas, vigas o losas, y 3) a nivel de la respuesta de edificios completos o de partes significativas de los mismos. Se desarrollan modelos de elementos finitos de continuo 3D muy detallados que modelizan el hormigón en masa y el acero de armado de forma segregada. El hormigón se representa con un modelo constitutivo del hormigón CSCM (Murray et al., 2007), que tiene un comportamiento inelástico, con diferente respuesta a tracción y compresión, endurecimiento, daño por fisuración y compresión, y rotura. El acero se representa con un modelo constitutivo elastoplástico bilineal con rotura. Se modeliza la geometría precisa del hormigón mediante elementos finitos de continuo 3D y cada una de las barras de armado mediante elementos finitos tipo viga, con su posición exacta dentro de la masa de hormigón. La malla del modelo se construye mediante la superposición de los elementos de continuo de hormigón y los elementos tipo viga de las armaduras segregadas, que son obligadas a seguir la deformación del sólido en cada punto mediante un algoritmo de penalización, simulando así el comportamiento del hormigón armado. En este trabajo se denominarán a estos modelos simplificadamente como modelos de EF de continuo. Con estos modelos de EF de continuo se analiza la respuesta estructural de elementos constructivos (columnas, losas y pórticos) frente a acciones explosivas. Asimismo se han comparado con resultados experimentales, de ensayos sobre vigas y losas con distintas cargas de explosivo, verificándose una coincidencia aceptable y permitiendo una calibración de los parámetros de cálculo. Sin embargo estos modelos tan detallados no son recomendables para analizar edificios completos, ya que el elevado número de elementos finitos que serían necesarios eleva su coste computacional hasta hacerlos inviables para los recursos de cálculo actuales. Adicionalmente, se desarrollan modelos de elementos finitos estructurales (vigas y láminas) que, con un coste computacional reducido, son capaces de reproducir el comportamiento global de la estructura con una precisión similar. Se modelizan igualmente el hormigón en masa y el acero de armado de forma segregada. El hormigón se representa con el modelo constitutivo del hormigón EC2 (Hallquist et al., 2013), que también presenta un comportamiento inelástico, con diferente respuesta a tracción y compresión, endurecimiento, daño por fisuración y compresión, y rotura, y se usa en elementos finitos tipo lámina. El acero se representa de nuevo con un modelo constitutivo elastoplástico bilineal con rotura, usando elementos finitos tipo viga. Se modeliza una geometría equivalente del hormigón y del armado, y se tiene en cuenta la posición relativa del acero dentro de la masa de hormigón. Las mallas de ambos se unen mediante nodos comunes, produciendo una respuesta conjunta. En este trabajo se denominarán a estos modelos simplificadamente como modelos de EF estructurales. Con estos modelos de EF estructurales se simulan los mismos elementos constructivos que con los modelos de EF de continuo, y comparando sus respuestas estructurales frente a explosión se realiza la calibración de los primeros, de forma que se obtiene un comportamiento estructural similar con un coste computacional reducido. Se comprueba que estos mismos modelos, tanto los modelos de EF de continuo como los modelos de EF estructurales, son precisos también para el análisis del fenómeno de colapso progresivo en una estructura, y que se pueden utilizar para el estudio simultáneo de los daños de una explosión y el posterior colapso. Para ello se incluyen formulaciones que permiten considerar las fuerzas debidas al peso propio, sobrecargas y los contactos de unas partes de la estructura sobre otras. Se validan ambos modelos con un ensayo a escala real en el que un módulo con seis columnas y dos plantas colapsa al eliminar una de sus columnas. El coste computacional del modelo de EF de continuo para la simulación de este ensayo es mucho mayor que el del modelo de EF estructurales, lo cual hace inviable su aplicación en edificios completos, mientras que el modelo de EF estructurales presenta una respuesta global suficientemente precisa con un coste asumible. Por último se utilizan los modelos de EF estructurales para analizar explosiones sobre edificios de varias plantas, y se simulan dos escenarios con cargas explosivas para un edificio completo, con un coste computacional moderado. The frequency of explosions on buildings whether they are intended or accidental is small, but they can have catastrophic effects. Being able to predict in a accurate enough manner the consequences of these dynamic actions on civil buildings, among which frame-type reinforced concrete buildings are a frequent typology is desirable. In this doctoral thesis different practical options for the modeling and computer assisted numerical calculation of reinforced concrete structures submitted to explosions are explored. Numerical finite elements models with explicit time-based integration are employed, demonstrating their effective capacity in the simulation of the occurring fast dynamic and highly nonlinear physical and structural phenomena, allowing to predict the damage caused by the explosion itself as well as by the possible progressive collapse of the structure. The work has been carried out with the commercial finite elements code LS-DYNA (Hallquist, 2006), developing several types of calculation model classified in two main types: 1) Models based in continuum finite elements in which the continuous medium is discretized directly by means of nodal displacement degrees of freedom; 2) Models based on structural finite elements, with beams and shells, including kinematic hypothesis for linear and superficial elements. These models are developed and discussed at different levels: 1) material behaviour, 2) response of structural elements such as columns, beams and slabs, and 3) response of complete buildings or significative parts of them. Very detailed 3D continuum finite element models are developed, modeling mass concrete and reinforcement steel in a segregated manner. Concrete is represented with a constitutive concrete model CSCM (Murray et al., 2007), that has an inelastic behaviour, with different tension and compression response, hardening, cracking and compression damage and failure. The steel is represented with an elastic-plastic bilinear model with failure. The actual geometry of the concrete is modeled with 3D continuum finite elements and every and each of the reinforcing bars with beam-type finite elements, with their exact position in the concrete mass. The mesh of the model is generated by the superposition of the concrete continuum elements and the beam-type elements of the segregated reinforcement, which are made to follow the deformation of the solid in each point by means of a penalty algorithm, reproducing the behaviour of reinforced concrete. In this work these models will be called continuum FE models as a simplification. With these continuum FE models the response of construction elements (columns, slabs and frames) under explosive actions are analysed. They have also been compared with experimental results of tests on beams and slabs with various explosive charges, verifying an acceptable coincidence and allowing a calibration of the calculation parameters. These detailed models are however not advised for the analysis of complete buildings, as the high number of finite elements necessary raises its computational cost, making them unreliable for the current calculation resources. In addition to that, structural finite elements (beams and shells) models are developed, which, while having a reduced computational cost, are able to reproduce the global behaviour of the structure with a similar accuracy. Mass concrete and reinforcing steel are also modeled segregated. Concrete is represented with the concrete constitutive model EC2 (Hallquist et al., 2013), which also presents an inelastic behaviour, with a different tension and compression response, hardening, compression and cracking damage and failure, and is used in shell-type finite elements. Steel is represented once again with an elastic-plastic bilineal with failure constitutive model, using beam-type finite elements. An equivalent geometry of the concrete and the steel is modeled, considering the relative position of the steel inside the concrete mass. The meshes of both sets of elements are bound with common nodes, therefore producing a joint response. These models will be called structural FE models as a simplification. With these structural FE models the same construction elements as with the continuum FE models are simulated, and by comparing their response under explosive actions a calibration of the former is carried out, resulting in a similar response with a reduced computational cost. It is verified that both the continuum FE models and the structural FE models are also accurate for the analysis of the phenomenon of progressive collapse of a structure, and that they can be employed for the simultaneous study of an explosion damage and the resulting collapse. Both models are validated with an experimental full-scale test in which a six column, two floors module collapses after the removal of one of its columns. The computational cost of the continuum FE model for the simulation of this test is a lot higher than that of the structural FE model, making it non-viable for its application to full buildings, while the structural FE model presents a global response accurate enough with an admissible cost. Finally, structural FE models are used to analyze explosions on several story buildings, and two scenarios are simulated with explosive charges for a full building, with a moderate computational cost.

Orden y naturaleza en la escuela al aire libre : el colegio para la Institución Teresiana en Alicante de Rafael de la Hoz y Gerardo Olivares

"No son necesarios imponentes edificios para dar una buena educación a los niños, mucho menos en zonas de clima suave. En el pasado Filósofos y Santos acostumbraban a sentarse con sus discípulos a la sombra de un árbol, transmitiéndoles su sabiduría sin necesidad de edificaciones de hormigón armado. Pero eran grandes hombres y grandes espíritus que sabían aprovechar el universo entero como material didáctico junto a los simples recursos de su inteligencia y su fantasía". Esta tesis nace con la intención de profundizar en la investigación de los mecanismos arquitectónicos que hicieron posible en un determinado tipo de escuelas la relación entre arquitectura y naturaleza, ya se entienda ésta como paisaje natural o como paisaje artificial creado ex novo. Si desde los tiempos de Lao Tse no había sido superada su definición de Arquitectura: “Arquitectura no son cuatro paredes y un tejado, arquitectura es el ordenamiento de los espacios y el espíritu que se genera dentro”; en realidad dicha definición adolecía de una gran carencia, pues nada decía del “espacio que queda fuera”. Así lo puso de manifiesto D. Rafael de La Hoz Arderius en su discurso de ingreso a la Real Academia de San Fernando5. Hubo que esperar al inicio del siglo XX para que la Arquitectura occidental se centrara de lleno en desmaterializar el límite entre el espacio construido y el “sitio” en el que se inserta, convirtiendo éste en “lugar” habitado. El “dentro” y el “fuera” dejan de entenderse como dos realidades antagónicas para dejar paso a un espacio continuo articulado a través de fructíferas situaciones intermedias. Sin embargo, poco se ha estudiado sobre una tipología arquitectónica : la escuela al aire libre, que fue crucial en la génesis tanto de los espacios educativos, como en la conformación del espacio Moderno así entendido. Éste es por tanto el objeto de la presente Tesis, desde una doble vertiente: por un lado desde la investigación de la evolución de esta tipología en general, y más detenidamente de un caso concreto, el colegio de las Teresianas en Alicante de Rafael de La Hoz Arderius y Gerardo Olivares James. La evolución de la escuela al aire libre se aborda a través de una selección de casos de estudio que ilustran que la regeneración social que pretendía acometerse no podía limitarse sólo a los aspectos higiénicos que centraron su primera etapa, sino que era necesario también reforzar el espíritu comunitario del niño como futuro ciudadano. Por otro lado el Colegio de las Teresianas en Alicante (1964) de Rafael de La Hoz Arderius y Gerardo Olivares James se ha elegido como caso de estudio específico. Este proyecto, siendo uno de los más desconocidos de sus autores, supone la culminación de sus investigaciones en torno a la escuela al aire libre8. Rafael de La Hoz, en línea con los postulados humanistas del Realismo Biológico de Richard Neutra, advertía de la imposibilidad de abordar la ordenación del espacio si desconocemos el proceso perceptivo del ser humano, destinatario de la Arquitectura. Esta dificultad es aún mayor si cabe cuando el destinatario no es el ser humano adulto sino el niño, dada su distinta percepción del binomio “espacio-tiempo”. En este sentido el colegio de las Teresianas en Alicante es además un ejemplo cercano, el único de los incluidos en la presente Tesis del que verdaderamente se ha podido tener un conocimiento profundo tanto por el resultado de su análisis a partir de una investigación de carácter científico, como por la experiencia personal del mismo vivida desde niña, al ser antigua alumna del centro. Tanto en este ejemplo concreto como en el resto de casos analizados la metodología para lograr la educación integral del individuo, reproduciendo el mito de la caverna de Platón revisado a través del Emilio roussoniano, se fundamenta en el contacto directo con el exterior, promoviendo un nuevo modo de vida equilibrado y en armonía con la naturaleza, con uno mismo y con los demás. Desde un primer estadio en el que el espacio exterior sustituye literalmente al aula como lugar para la enseñanza, se evoluciona hacia una tipología más compleja en la que los mecanismos de proyecto habrán de fomentar la continuidad entre interior y exterior en los espacios de aprendizaje, así como reproducir en el interior del aula las ventajas del ambiente exterior evitando algunos de sus inconvenientes. Todo ello con diferentes matices según la edad del alumno y la climatología del lugar. A partir del análisis de los casos de estudio generales y del ejemplo concreto de las Teresianas, se pretende sintetizar cuales fueron los mecanismos de proyecto y los principales temas de reflexión que caracterizaron este tipo de escuelas. ABSTRACT "Imposing buildings are not necessary for children to receive a good education, even less in mild climate areas. In the past, Philosophers and Saints used to sit with their disciples in the shade of a tree, passing on their wisdom without the need of reinforced concrete buildings. But they were great men and great minds who could take advantage of the entire universe as a source of teaching material, together with their intelligence and fantasy." This thesis was undertaken with the purpose of carrying out an in depth analysis of the architectural strategies targeting certain types of schools which have a close relationship between architecture and nature. It is said that since the time of Lao Tzu his definition of architecture had not been surpassed: “architecture is not just four walls and a roof, architecture is the arrangement of the spaces and the spirit that is generated within”. But this definition suffered from a serious lack as the “space left outside” is not mentioned. This was exposed by Rafael de La Hoz Arderius in his speech of entry into the Royal Academy of San Fernando10. It was not until the early twentieth century that Western architecture would squarely focus on dematerializing the boundary between the built environment and the “site” in which it is inserted, turning it into an inhabited “place”. The “inside” and the “outside” are no longer understood as two op-posed realities, instead they make way for a continuous space articulated through fruitful in-between situations. However, little has been studied about an architectural typology: the open air school, which was a turning point in the genesis of both educational, as well as modern space. This is therefore the object of this thesis, having two perspectives. On the one hand the development of this type of school is broadly investigated; on the other hand a specific case is introduced: the school of the Teresian association of Alicante, by Rafael de La Hoz and Gerardo Olivares. The development of the open air school is approached through a selection of case studies. These illustrate that the expected social regeneration could not be limited exclusively by the hygienic aspects targeting its first stage, but it was also necessary to strengthen the community spirit of the child as a future citizen. As previously mentioned the Teresian school of Alicante (1964-1966), has been chosen as a specific case study. Despite being quite a bit less renowned than other projects by the same authors, it represents the culmination of their researches about the open air school. In line with the humanist postulates of Richard Neutra’s Biological Realism, Rafael de La Hoz warned about the inability to deal with the arrangement of space if we are unaware of the perceptive process of the human being, addressee of the architecture. This difficulty becomes greater when the addressee is not the adult human but the child, given his different perception of the binomial “space-time” relationship. In this respect the Teresian school of Alicante is in addition a closely related case study, being the only one of the mentioned cases in this thesis allowing to acquire a deep knowledge, both from the results of its analysis coming from a research of scientific nature, as well as the personal experience lived since I was a child, given that I am a former pupil. Both in this case study and in the other analyzed cases, the methodology implemented to achieve the integral education of the individual is based on the direct contact with the exterior, promoting a balanced and in harmony with nature new way of life, including oneself and the others. Thereby it replicates the Plato’s cavern myth and its roussonian review: Emilio. From the first stage in which the exterior literally substitutes the classroom as the educational space, it is evolved towards a more complex typology in which the project strategies have to promote the continuity between inside and outside learning spaces, as well as to reproduce inside the classroom the advantages of the exterior environment avoiding some of its disadvantages; thereto considering the differing matrixes involving the pupil age and the local climatology. From the analysis of the general case studies and the Teresian school, the main project strategies and elements characterizing the open air school have been synthesized.

La introducción del hormigón armado en España: razón constructiva de su evolución

España se incorporó a la técnica del hormigón armado con más de dos décadas de retraso respecto a Francia o Alemania. En 1890, en Europa se construían ya estructuras de hormigón armado de cierta envergadura y complejidad. En España hubo que esperar hasta 1893 para la primera obra en hormigón armado, que fue un sencillo depósito descubierto en Puigverd (Lérida), ejecutado por el ingeniero militar Francesc Macià con patente Monier. En 1898, de la mano de Hennebique, se empezó la construcción de los dos primeros edificios con estructura de hormigón armado en España. Fueron dos obras puntuales, con proyectos importados de Francia, pero necesarias para introducir de manera definitiva el material. En paralelo, en París, se estaban edificando en hormigón armado la mayoría de los pabellones de la Exposición Universal de 1900. En el cambio de siglo, las construcciones de hormigón armado habían alcanzado ya la madurez proyectual y técnica en Europa. A pesar de la incorporación tardía, se puede constatar por las obras ejecutadas que en un periodo corto de tiempo, entre 1901 y 1906, se alcanzó en España prácticamente el mismo nivel técnico y constructivo que tenían el resto de los países que fueron pioneros en el empleo del hormigón armado. El desarrollo e implantación de una técnica constructiva no es un proceso lineal, y son muchos los factores que intervienen. Las patentes tuvieron una gran importancia en el desarrollo inicial del hormigón armado. Estas ofrecían un producto que funcionaba. Las primeras estructuras de hormigón armado no se calculaban y se construían siguiendo una reglamentación, se compraban. Y el resultado de esa “compra” solía ser, en la mayoría de los casos, satisfactorio. Las patentes vendían sistemas estructurales cuyo funcionamiento estaba corroborado por la experiencia y la pericia de su inventor. Esta investigación parte de la hipótesis de que las patentes sobre cemento y hormigón armado depositadas en España entre 1884 y 1906 fueron uno de los factores que proporcionaron a los técnicos y a las empresas españolas una pericia constructiva sólida en el empleo del hormigón armado. En este trabajo se aborda el estudio del proceso de introducción del hormigón armado en España desde una perspectiva fundamentalmente técnica, incorporando las patentes como una de las razones constructivas que explican su rápida evolución y generalización en un periodo de tiempo breve: 1901-1906. En este proceso se contextualiza y analiza una de las figuras que se considera fundamental en los primeros años del hormigón armado en España, la del ingeniero Juan Manuel de Zafra y Estevan. Esta tesis analiza las patentes de hormigón armado desde el punto de vista estadístico y constructivo. Desde ambas perspectivas se verifica la hipótesis de partida de esta investigación, concluyendo que las patentes fueron una de las razones constructivas de la evolución del hormigón armado en España y de su rápida implantación. ABSTRACT Spain incorporated the reinforced concrete technique more than two decades after France and Germany. In central Europe reinforced concrete structures of considerable size and complexity were being built in 1890, while in Spain it was not until 1893 that the first work, a simple open air water tank, was implemented in Puigverd (Lleida) by the military engineer Francesc Macià with a Monier patent. In 1898 the construction of the first two buildings with reinforced concrete structure in Spain started, with the guidance by Hennebique. They were two isolated cases with projects imported from France, but playing a key role to definitively introduce the material in Spain. In parallel, in Paris, most of the pavilions of the 1900 World Expo were being built in reinforced concrete. At the turn of the century reinforced concrete buildings had reached maturity both as a technology and as a design practice. Despite the late assumption of the material, the works carried out in the very short period between 1901 and 1906 clearly show that Spain reached practically the same technical and constructive level as the other pioneering countries in the use of reinforced concrete. The development and implementation of a constructive technique is never a linear process, there are many factors involved. The patents offered a successful product. Initial reinforced concrete structures were not calculated and built according to regulations, they were bought. And this purchase in most cases was satisfactory for the required use. Patents sold structural systems whose performance was supported by the experience and expertise of its inventor. The hypothesis of this research is based upon the assumption that the cement and concrete patents registered in Spain between 1884 and 1906 were one of the factors that provided Spanish technicians and companies with a solid constructive expertise in the use of reinforced concrete. This investigation studies the introduction of reinforced concrete to Spain from a predominantly technical perspective, incorporating patents as the constructive reason for the rapid evolution and spread in such a short period of time: 1901-1906. Along the way, the role of engineer J. M. de Zafra, generally considered a key agent in the initial years of reinforced concrete in Spain, is contextualized and analyzed. This dissertation analyzes the patents of reinforced concrete from a statistical and constructive point of view. From both perspectives the hypothesis of this research is verified, concluding that patents were one of the constructive reasons for the development of reinforced concrete in Spain.

A first approach to earthquake damage estimation in Haiti: advices to minimize the seismic risk

This study is in the frame of the cooperative line that several Spanish Universities and other foreign partners started with the Haitian government in 2010. According to our studies (Benito et al. in An evaluation of seismic hazard in La Hispaniola, after the 2010 Haiti earthquake, 33rd General Assembly of the European Seismological Commission, Moscow, Russia, 2012) and recent scientific literature, the earthquake hazard in Haiti remains high (Calais et al. in Nat Geosci 3:794–799, 2010). In view of this, we wonder whether the country is currently ready to face another earthquake. In this sense, we estimated several damage scenarios in Port-au-Prince and Cap-Haitien associated to realistic possible major earthquakes. Our findings show that almost 50 % of the building stock of both cities would result uninhabitable due to structural damage. Around 80 % of the buildings in both cities have reinforced concrete structure with concrete block infill; however, the presence of masonry buildings becomes significant (between 25 and 45 % of the reinforced concrete buildings) in rural areas and informal settlements on the outskirts, where the estimated damage is higher. The influence of the soil effect on the damage spatial distribution is evident in both cities. We have found that the percentage of uninhabitable buildings in soft soil areas may be double the percentage obtained in nearby districts located in hard soil. These results reveal that a new seismic catastrophe of similar or even greater consequences than the 2010 Haiti earthquake might happen if the earthquake resilience is not improved in the country. Nowadays, the design of prevention actions and mitigation policies is the best instrument the society has to face seismic risk. In this sense, the results of this research might contribute to define measures oriented to earthquake risk reduction in Haiti, which should be a real priority for national and international institutions.

Comportamento e reforço de nós viga-pilar

A presente dissertação tem como principal objetivo a análise do comportamento do nó viga-pilar, com a finalidade de dimensionar uma solução de reforço sísmico a aplicar em nós de estruturas antigas de betão armado. Uma parte considerável das construções em betão armado construídas em Portugal até 1970 são muito frágeis relativamente às ações sísmicas. Devido a este fato, os edifícios estão associados a uma conceção desajustada face à regulamentação atual pois à época não estava prevista a consideração de ações sísmicas na execução dos projetos de estruturas. Nesse período, era prática comum na construção o uso de armadura lisa conjugada com uma má pormenorização das armaduras e baixa resistência mecânica do betão. Tal levava a que as estruturas de betão armado construídas em Portugal até à década de setenta, possuírem uma baixa capacidade para resistir a solicitações cíclicas, como as induzidas pelos sismos. Os nós viga-pilar das estruturaras de betão armado são considerados as zonas mais crítica e vulnerável a ações sísmicas. Por isso é frequente em estruturas antigas, a necessidade de as reforçar, para melhorar a performance do edifício durante os sismos. Têm sido estudadas por investigadores várias técnicas e soluções para reforçar os nós viga-pilar de estruturas antigas de betão armado. Serão analisados nesta dissertação os danos observados em dois nós viga-pilar ensaiados experimentalmente, onde são simuladas as ações cíclicas horizontais dos sismos. Com base nestes dados, é proposta e detalhada uma solução de reforço para melhorar o comportamento histerético dessa ligações, de forma a conferir uma maior capacidade resistente e/ou ductilidade.

Decision support in using fibre reinforced polymer (FRP) composites in rehabilitation of concrete bridge structures

This paper compares and reviews the recommendations and contents of the guide for the design and construction of externally bonded FRP systems for strengthening concrete structures reported by ACI committee 440 and technical report of Externally bonded FRP reinforcement for RC structures (FIB 14) in application of carbon fiber reinforced polymer (CFRP) composites in strengthening of an aging reinforced concrete headstock. The paper also discusses the background, limitations, strengthening for flexure and shear, and other related issues in use of FRP for strengthening of a typical reinforced concrete headstock structure such as durability, de-bonding, strengthening limits, fire and environmental conditions. A case study of strengthening of a bridge headstock using FRP composites is presented as a worked example in order to illustrate and compare the differences between these two design guidelines when used in conjunction with the philosophy of the Austroads (1992) bridge design code.

Investigation of hybridized polyurethane, glass fibre reinforced cement and steel laminate in structural floor plate systems

Sandwich components have emerged as light weight, efficient, economical, recyclable and reusable building systems which provide an alternative to both stiffened steel and reinforced concrete. These components are made of composite materials in which two metal face plates or Glassfibre Reinforced Cement (GRC) layers are bonded and form a sandwich with light weight compact polyurethane (PU) elastomer core. Existing examples of product applications are light weight sandwich panels for walls and roofs, Sandwich Plate System (SPS) for stadia, arena terraces, naval construction and bridges and Domeshell structures for dome type structures. Limited research has been conducted to investigate performance characteristics and applicability of sandwich or hybrid materials as structural flooring systems. Performance characteristics of Hybrid Floor Plate Systems comprising GRC, PU and Steel have not been adequately investigated and quantified. Therefore there is very little knowledge and design guidance for their application in commercial and residential buildings. This research investigates performance characteristics steel, PU and GRC in Hybrid Floor Plate Systems (HFPS) and develops a new floor system with appropriate design guide lines.

Interactive axial shortening of columns and walls in high rise buildings

Concrete is commonly used as a primary construction material for tall building construction. Load bearing components such as columns and walls in concrete buildings are subjected to instantaneous and long term axial shortening caused by the time dependent effects of "shrinkage", "creep" and "elastic" deformations. Reinforcing steel content, variable concrete modulus, volume to surface area ratio of the elements and environmental conditions govern axial shortening. The impact of differential axial shortening among columns and core shear walls escalate with increasing building height. Differential axial shortening of gravity loaded elements in geometrically complex and irregular buildings result in permanent distortion and deflection of the structural frame which have a significant impact on building envelopes, building services, secondary systems and the life time serviceability and performance of a building. Existing numerical methods commonly used in design to quantify axial shortening are mainly based on elastic analytical techniques and therefore unable to capture the complexity of non-linear time dependent effect. Ambient measurements of axial shortening using vibrating wire, external mechanical strain, and electronic strain gauges are methods that are available to verify pre-estimated values from the design stage. Installing these gauges permanently embedded in or on the surface of concrete components for continuous measurements during and after construction with adequate protection is uneconomical, inconvenient and unreliable. Therefore such methods are rarely if ever used in actual practice of building construction. This research project has developed a rigorous numerical procedure that encompasses linear and non-linear time dependent phenomena for prediction of axial shortening of reinforced concrete structural components at design stage. This procedure takes into consideration (i) construction sequence, (ii) time varying values of Young's Modulus of reinforced concrete and (iii) creep and shrinkage models that account for variability resulting from environmental effects. The capabilities of the procedure are illustrated through examples. In order to update previous predictions of axial shortening during the construction and service stages of the building, this research has also developed a vibration based procedure using ambient measurements. This procedure takes into consideration the changes in vibration characteristic of structure during and after construction. The application of this procedure is illustrated through numerical examples which also highlight the features. The vibration based procedure can also be used as a tool to assess structural health/performance of key structural components in the building during construction and service life.