2011:30 ABE

A criação de programas federais voltados para o desenvolvimento da infraestrutura brasileira no final da década passada resultou no aquecimento do setor de construção civil. Nesse contexto, o sistema de paredes de concreto moldadas no local se destacou devido à sua alta produtividade e repetitividade. Os requisitos e procedimentos para o dimensionamento de paredes de concreto moldadas no local são contemplados na NBR 16055:2012. Dentre as abordagens consideradas nessa norma, ressalta-se a recomendação do uso de concreto autoadensável. No entanto, alguns pontos de interesse não são contemplados na regulamentação vigente como, por exemplo, a incorporação de ar na composição do concreto, bem como os limites de teores de ar incorporado. Assim, a presente pesquisa busca avaliar a influência da incorporação de ar no comportamento de concretos autoadensáveis destinados à execução de paredes de concreto moldadas no local. Para isso, foram produzidos dois traços de concreto autoadensável de classes de resistência C25 e C40 e, a partir de cada um deles, produzidos outros dois traços modificados com aditivo incorporador de ar, variando o teor de ar incorporado, em um total de seis misturas cujas propriedades foram avaliadas tanto no estado fresco quanto no estado endurecido. Além disso, foram moldadas paredes de concreto a fim de analisar a estrutura interna do material com aparelho de ultrassom e o acabamento superficial do elemento por meio de análise de imagens. No caso da classe C25, os resultados demonstram que a influência do teor de ar para os traços modificados foi tão significativa que os concretos produzidos se tornaram inadequados para uso estrutural. Por outro lado, apesar da elevada perda de resistência à compressão aos 28 dias, os dois traços produzidos com incorporação de ar no concreto de classe C40 se adequam às recomendações da NBR 16055:2012. Alia-se a isso o fato de que, quando da execução das paredes em laboratório, os concretos utilizados demonstraram grande capacidade de preenchimento, resultando em elementos com bom acabamento superficial e estrutura interna homogênea, mesmo em regiões de difícil acesso. Sendo assim, o presente trabalho propõe traços muito promissores para utilização em paredes de concreto moldadas no local. / The creation of federal programs aimed at the development of Brazilian infrastructure at the end of the last decade resulted in the heating of civil construction sector. In this context, the system of concrete walls cast in place stood out due to its high productivity and repetitiveness. The requirements and procedures for the design of concrete walls cast in place are contemplated in the NBR 16055:2012. Among the several approaches considered in this code, the recommendation for the use of self-compacting concrete is emphasized. However, some points of interest are not considered in the current regulations, such as the incorporation of air in the concrete composition, as well as the limits for entrained air contents. Thus, the present research seeks to evaluate the influence of air entrainment in the behaviour of self-compacting concrete for the construction of concrete walls cast in place. For this, two self-compacting concrete mixes design of strength classes C25 and C40 were produced and, from each of them, two other mixes modified with air entraining admixture were produced, varying the entrained air content, in a total of six mixtures whose properties were evaluated in both fresh and hardened state. In addition, concrete walls were cast to analyse the internal structure with ultrasonic equipment and the element surface finish by image analysis. In the case of class C25, the results demonstrate that the influence of the air content for the modified mixes was so great that the concretes produced became inappropriate for structural use. On the other hand, despite the high loss of compressive strength at 28 days, the two mixes produced with entrained air in the concrete of class C40 respect the recommendations of the NBR 16055:2012. In addition, when the walls were cast in laboratory, the concretes used showed great filling capacity, resulting in structures with good surface finish and homogeneous internal structure, even in difficult access regions. Therefore, the present work proposes very promising mixes for use in concrete walls cast in place.

Neste trabalho são realizadas análises estruturais de edifícios de paredes de concreto moldadas no local e de alvenaria estrutural considerando a interação solo-estrutura e a sequência construtiva. Com solução de fundação em estacas pré-moldadas, cada edifício piloto com 45 metros de altura, formado por 15 pavimentos de parede com pé-direito de 2,80m, apoiado sobre um pilotis de concreto armado de 3 metros de altura é modelado com base em 4 metodologias de análise: (i) O AI_AF, modelo clássico de referência, que admite apoios indeslocáveis e ações instantâneas; (ii) O AE_AF, modelo que inclui as ações evolutivas, incorporando o aumento gradativo de carregamento e rigidez; (iii) O AI_ISE, modelo que incorpora a interação com o solo a partir da aplicação instantânea de ações e (iv) o AE_ISE, modelo mais refinado, que considera a interação com o solo no tempo de construção. As paredes são modeladas em elementos finitos de casca, os pilares de concreto, vigas de transição, estacas e blocos em elementos finitos de barra e o maciço de solo em elementos finitos sólidos isoparamétricos, com o auxílio do software comercial DIANA®. O trabalho evidencia que o modelo clássico de referência, que desconsidera a interação com o solo, não alerta para a necessidade de aumentar a ductilidade das paredes dos pavimentos iniciais em ambos os sistemas construtivos. / This study consist of a structural analyses of concrete walls and masonry building including the soil-structure interaction and the construction process. Each pilot building is 45 meters high, consisting of 15 floors with 2.80 m high. Each floors are seated on pillars of reinforced concrete with 3 meters of height, which were modeled using 4 methodologies: (i) The AI_AF, classic reference model, which adopts fixed foundations and instantaneous action; (ii) The AE_AF is a model, that includes construction loads and incorporates a gradual increasing in load and stiffness; (iii) The AI_ISE model incorporates interaction with the soil and the instantaneous application of actions; and, (iv) AE_ISE, which consists of a more refined model with soil interaction and the time of construction. The concrete walls are modeled based on shell finite elements, the concrete pillars, transition beams, stakes and blocks are modeled based on bar finite element and the soil mass is modelled as an isoparametric solid finite elements. The numerical modelling is conducted using commercial software DIANA®. Results show that the classic reference model, in which the soil-structure interaction is not considered, does not attent to the need of increasing the ductility of the walls in initials floor.

In this thesis we look at one of the aging mechanisms that may have affected current aged Nuclear Power Plants (NPPs). Irradiation as an age-related degradation mechanism is studied for Reinforced Concrete (RC) in NPPs. This problem can be important for aged reactor buildings, radwaste buildings, spent nuclear fuel, research reactors, or accelerators that experience high levels of radiation close to existing thresholds. Mechanical properties of concrete are the most important parameters affected by radiation in NPPs. Compressive strength of concrete is reduced between 80 and 35 \% for radiation fluences between $2\times 10^{19}$ and $2\times 10^{21} n/cm^2$. Tensile strength reduction is more significant than compressive strength. It is reduced between 20 and 80 \% for a radiation fluence equal to $5\times 10^{19}$. We chose three radiation levels $2\times 10^{19}$, $2\times 10^{20}$, $2\times 10^{20}$ based on experimental results as the critical levels of radiation that RC structures in NPPs may be exposed to. Structures susceptible to the problem are mostly RC walls; so the RC panel is chosen as an appropriate representative scale element for the analysis. The effect of radiation on mechanical properties of concrete is considered to analyze degraded scale elements. Material properties, geometry, and loading scenarios of scale elements are selected to be close to actual quantities in existing nuclear power plant. Elements are analyzed under six types of loading combination of shear and axial loading conditions. A nonlinear finite element program, Membrane-2000, based on the Modified Compression Field Theory (MCFT) is used to solve scale elements numerically. Element behaviors are studied considering the factors influence ultimate strength capacity, failure mode, and structural ductility index of members. The results show that ultimate shear capacity of the elements subjected to combinations of shear and tension loading are reduced significantly for highly reinforced elements ($1.35<\rho<1.88$) in $2\times 10^{21} n/cm^2$ radiation. RC panels under shear-biaxial and uniaxial compression also show significant strength capacity reduction in radiation levels $2\times 10^{20} n/cm^2$ and $2\times 10^{21} n/cm^2$, respectively. Failure modes of the elements change from yielding of steel to shear failure by increasing level of degradation for the elements with reinforcement ratio between 0.9 and 1.88. Ductility of the RC panels is reduced significantly in the critical levels of radiation. Ductility of the elements became less than the allowable ductility value by increasing level of radiation.

In this thesis we look at one of the aging mechanisms that may have affected current aged Nuclear Power Plants (NPPs). Irradiation as an age-related degradation mechanism is studied for Reinforced Concrete (RC) in NPPs. This problem can be important for aged reactor buildings, radwaste buildings, spent nuclear fuel, research reactors, or accelerators that experience high levels of radiation close to existing thresholds. Mechanical properties of concrete are the most important parameters affected by radiation in NPPs. Compressive strength of concrete is reduced between 80 and 35 \% for radiation fluences between $2\times 10^{19}$ and $2\times 10^{21} n/cm^2$. Tensile strength reduction is more significant than compressive strength. It is reduced between 20 and 80 \% for a radiation fluence equal to $5\times 10^{19}$. We chose three radiation levels $2\times 10^{19}$, $2\times 10^{20}$, $2\times 10^{20}$ based on experimental results as the critical levels of radiation that RC structures in NPPs may be exposed to. Structures susceptible to the problem are mostly RC walls; so the RC panel is chosen as an appropriate representative scale element for the analysis. The effect of radiation on mechanical properties of concrete is considered to analyze degraded scale elements. Material properties, geometry, and loading scenarios of scale elements are selected to be close to actual quantities in existing nuclear power plant. Elements are analyzed under six types of loading combination of shear and axial loading conditions. A nonlinear finite element program, Membrane-2000, based on the Modified Compression Field Theory (MCFT) is used to solve scale elements numerically. Element behaviors are studied considering the factors influence ultimate strength capacity, failure mode, and structural ductility index of members. The results show that ultimate shear capacity of the elements subjected to combinations of shear and tension loading are reduced significantly for highly reinforced elements ($1.35<\rho<1.88$) in $2\times 10^{21} n/cm^2$ radiation. RC panels under shear-biaxial and uniaxial compression also show significant strength capacity reduction in radiation levels $2\times 10^{20} n/cm^2$ and $2\times 10^{21} n/cm^2$, respectively. Failure modes of the elements change from yielding of steel to shear failure by increasing level of degradation for the elements with reinforcement ratio between 0.9 and 1.88. Ductility of the RC panels is reduced significantly in the critical levels of radiation. Ductility of the elements became less than the allowable ductility value by increasing level of radiation.

Neste trabalho são realizadas análises estruturais de edifícios de paredes de concreto moldadas no local e de alvenaria estrutural considerando a interação solo-estrutura e a sequência construtiva. Com solução de fundação em estacas pré-moldadas, cada edifício piloto com 45 metros de altura, formado por 15 pavimentos de parede com pé-direito de 2,80m, apoiado sobre um pilotis de concreto armado de 3 metros de altura é modelado com base em 4 metodologias de análise: (i) O AI_AF, modelo clássico de referência, que admite apoios indeslocáveis e ações instantâneas; (ii) O AE_AF, modelo que inclui as ações evolutivas, incorporando o aumento gradativo de carregamento e rigidez; (iii) O AI_ISE, modelo que incorpora a interação com o solo a partir da aplicação instantânea de ações e (iv) o AE_ISE, modelo mais refinado, que considera a interação com o solo no tempo de construção. As paredes são modeladas em elementos finitos de casca, os pilares de concreto, vigas de transição, estacas e blocos em elementos finitos de barra e o maciço de solo em elementos finitos sólidos isoparamétricos, com o auxílio do software comercial DIANA®. O trabalho evidencia que o modelo clássico de referência, que desconsidera a interação com o solo, não alerta para a necessidade de aumentar a ductilidade das paredes dos pavimentos iniciais em ambos os sistemas construtivos. / This study consist of a structural analyses of concrete walls and masonry building including the soil-structure interaction and the construction process. Each pilot building is 45 meters high, consisting of 15 floors with 2.80 m high. Each floors are seated on pillars of reinforced concrete with 3 meters of height, which were modeled using 4 methodologies: (i) The AI_AF, classic reference model, which adopts fixed foundations and instantaneous action; (ii) The AE_AF is a model, that includes construction loads and incorporates a gradual increasing in load and stiffness; (iii) The AI_ISE model incorporates interaction with the soil and the instantaneous application of actions; and, (iv) AE_ISE, which consists of a more refined model with soil interaction and the time of construction. The concrete walls are modeled based on shell finite elements, the concrete pillars, transition beams, stakes and blocks are modeled based on bar finite element and the soil mass is modelled as an isoparametric solid finite elements. The numerical modelling is conducted using commercial software DIANA®. Results show that the classic reference model, in which the soil-structure interaction is not considered, does not attent to the need of increasing the ductility of the walls in initials floor.

This research aims to evaluate the thermal performance of housing built with the technology of reinforced concrete walls executed on site, for use in Brazilian Bioclimatic Zone 2. The study was conducted through in situ measurements of air temperature inside the four main types of single family housing of social interest of Zilda Arns allotment, in the town of Santa Maria-RS. Measurements were made in winter and summer, with the housing closed and also with the housing closed with sealing in places susceptible to air infiltration. The evaluations were made from the relationship between changes in internal temperatures and outdoor temperatures, and considering the influences of solar orientation and air infiltration, and internal thermal comfort through a comparative analysis of temperatures with ASHRAE (2004) limits. It was observed that the solar orientation has influence during winter and summer, however the air infiltration has little influence on thermal performance of housings. It was also observed that the building system provides good thermal performance for the summer period, but is not suitable to Bioclimatic Zone 2 during winter. As for thermal comfort, the housings presented cold discomfort for the whole period of winter and presented comfort in most of the analyzed summer period. / O presente trabalho tem como objetivo avaliar o desempenho térmico e o conforto térmico de habitações construídas com a tecnologia de paredes de concreto armado executadas no local, para uso na Zona Bioclimática 2 brasileira. O estudo foi realizado através de medições in loco da temperatura do ar no interior de quatro unidades com orientações solares predominantes de habitações unifamiliares de interesse social do loteamento Zilda Arns, na cidade de Santa Maria-RS. Foram feitas medições no inverno e no verão, com a casa fechada e também com a casa fechada com vedação nos locais passíveis de infiltração de ar. As avaliações foram .efetuadas a partir da relação entre as variações das temperaturas internas e das temperaturas externas, considerando ainda as influências da orientação solar e da infiltração de ar, e as condições de conforto térmico internas através de uma análise comparativa de temperaturas com valores limites da ASHRAE (2004). Foi observado que a orientação solar exerce influência nos períodos de inverno e verão, porém verificou-se que a infiltração de ar pouco influencia sobre o desempenho térmico das unidades. Observou-se ainda que o sistema construtivo apresenta bom desempenho térmico para o período de verão, porém não é adequado à Zona Bioclimática 2 no período de inverno. Quanto ao conforto térmico, as habitações apresentaram desconforto por frio em todo o período analisado de inverno e conforto na maior parte do período de verão.

Vid byggnation av betongväggar på vatten- och reningsverk används dom tvåmetoderna platsgjutna och prefabricerade väggar. Metoderna ger liknande resultatmen skiljer sig avsevärt i genomförande. Vi har därför valt att studera ämnet och draslutsatser om vilken metod som är att föredra.För att studera ämnet valde vi Skebäcks Reningsverk i Örebro som studieobjekt därdom båda metoderna att uppföra nya mellanväggar i betong har använts i sambandmed ombyggnation av befintliga bassänger.Vi har valt att studera kostnader och arbetsmiljöfrågor kring dom två olikabyggmetoderna.Som underlag för kostnadsberäkningen har vi använt Wikells Sektionsdata samtprisuppgifter från leverantörer. För att studera arbetsmiljön har intervjuer genomförtsmed två yrkesverksamma betongarbetare. Intervjuerna gav sedan underlag för enenkät som skickades ut till yrkesverksamma betongarbetare.Vår studie visar att prefabricerade väggar beräknas ge en lägre byggkostnad änmotsvarande platsgjuten vägg vid ett reningsverk. Studien visar även attbetongarbetare föredrar prefabricerade lösningar ur arbetsmiljösynpunkt. Fysisktpåfrestande moment undviks och tiden som spenderas på arbetsplatsen minskar vidprefabricerade betongelement. / When building concrete walls at water and wastewater treatment plants , the twomethods are cast-in-place and prefabricated walls. The methods give similar resultsbut differ considerably in implementation. We have therefore chosen to study thesubject and draw conclusions about which method is preferable.To study the subject, we chose Skebäcks wastewater treatment plant in Örebro as astudy object where both methods of constructing newpartitions in concrete havebeen used in connection with the reconstruction of existing basins.We have chosen to study costs and work environment issues around the twodifferent construction methods. As a basis for the cost calculation, we have usedWikell's Sektion Data and price information from suppliers. To study the workenvironment, interviews were conducted with two professional concrete workers. Theinterviews then provided the basis for a questionnaire that was given to professionalconcrete workers.Our study shows that prefabricated walls provide a lower construction cost than thecorresponding cast-in-place wall at wastewater treatment plant . The study showsthat concrete workers prefer prefabricated solutions from a work environment pointof view. Physically stressful moments are avoided and the time spent in theworkplace is reduced when building with prefabricated concrete walls.

Le présent travail propose et développe une méthode originale de dimensionnement vis-à-vis de l'incendie de parois de bâtiments industriels, en s'intéressant plus spécifiquement au cas des panneaux en béton armé de grande hauteur. Soumis à un fort gradient thermique, ces derniers subissent en effet des déplacements hors plan importants qui, du fait de l'excentrement du poids propre qui en résulte, vont engendrer des efforts de flexion venant s'ajouter aux efforts de compression déjà existants. Un tel changement de géométrie, d'autant plus prononcé que le panneau est de grande hauteur, combiné à une dégradation simultanée des propriétés de résistance des matériaux sous l'effet de l'élévation de température, peut conduire à un effondrement de la structure sous poids propre, bien avant par exemple l'apparition d'une instabilité de type flambement. L'approche proposée repose très largement sur la théorie du Calcul à la Rupture, appliquée d'une part à la détermination d'un diagramme d'interaction au feu caractérisant la résistance du panneau en chacune de ses sections, d'autre part à l'analyse de la ruine globale du panneau dans sa configuration déformée. Cette démarche est d'abord mise en œuvre et complètement explicitée dans le cas où le panneau peut être modélisé comme une poutre unidimensionnelle, conduisant à la détermination exacte d'un facteur adimensionnel caractérisant la stabilité de ce dernier. La généralisation de la méthode de calcul à la configuration plus réaliste, mais plus complexe, d'un panneau schématisé comme une plaque rectangulaire, est ensuite développée. Elle aboutit à un certain nombre de résultats préliminaires qui devront être confortés et affinés dans un travail ultérieur. L'approche théorique ici présentée est par ailleurs complétée par un volet expérimental (essais de flexion quatre points de dalles dans un four à maquette) qui a permis de valider au moins partiellement les évaluations du diagramme d'interaction prédites par le calcul / In this contribution, an original and comprehensive method aimed at designing vertical concrete walls submitted to fire loadings, is proposed and developed, with a special emphasis on high rise panels used in industrial buildings. Indeed, when subjected to high thermal gradients, such slender structures exhibit quite significant out-of-plane movements, resulting in an eccentricity of the gravity loads and thus to bending moments in addition to the pre-existing compressive forces. It is such a change of geometry, which is all the more pronounced as the panel is tall, combined with a temperature-induced degradation of the constituent materials strength properties, which may explain why an overall collapse of the structure may occur, well prior to buckling instability. The proposed approach is fundamentally based on the theory of yield design. This theory is first applied to the determination of an interaction diagram, characterizing the fire resistance of a reinforced concrete panel cross-section. It is then implemented as a design method for analysing the stability of the panel in its previously calculated deformed configuration. The whole procedure is explained in full details in the simplified situation when the high rise panel can be modeled as a one-dimensional beam, leading to the exact determination of a dimensionless factor characterizing the stability of the panel. The method is then extended to deal with a more realistic, but somewhat more complex, configuration of a rectangular panel. Some preliminary results, which need to be further validated in a subsequent work, are finally produced. As a necessary complement to the mostly theoretical and computational approach presented in this work, a series of four-point bending tests has been performed on reduced scale slabs placed in a furnace. The results of these tests partially validate the predicted interaction diagram of a fire loaded panel section