Las edificaciones construidas sobre suelo costero, ubicados sobre el cinturón del fuego presentan un alto riesgo sísmico, ya que sobre estas existen condiciones de suelo desfavorables y en otros casos subducción de placas. Esto ha conllevado a que los países ubicados en estas zonas desarrollen normativas sísmicas que permitan el diseño adecuado de obras de ingeniería; sin embargo, diversos reglamentos presentan distintas consideraciones para el diseño como la utilización de los parámetros que permiten estandarizar el diseño que muchas veces no presentan las mismas respuestas sísmicas del comportamiento dinámico real del suelo. Por ello, la presente investigación propone evaluar la respuesta sísmica de dos edificaciones, una esencial y otra común, con un análisis utilizando espectros de sitio, un análisis dinámico modal espectral y adicionalmente un análisis tiempo-historia teniendo consideraciones de tipos de suelo y utilización de distintos parámetros sísmicos de normas sudamericanas. El principal resultado es que la respuesta sísmica por análisis con espectros de sitio (ES) es mayor en comparación con el análisis dinámico modal espectral según la magnitud de los sismos y la tipología de suelos. / The buildings built on coastal soil, located on the fire belt present a high seismic risk, since there are unfavorable soil conditions and in other cases plate subduction. This has led to countries located in these areas developing seismic regulations that allow the proper design of engineering works; however, various regulations present different considerations for the design, such as the use of parameters that allow standardizing the design that often does not present the same seismic responses of the real dynamic behavior of the soil. Therefore, the present research proposes to evaluate the seismic response of two buildings, one essential and the other common, with an analysis using site spectra, a dynamic spectral modal analysis and additionally a time-history analysis taking into account soil types and use of different seismic parameters of South American standards. The main result is that the seismic response by analysis with site spectra (ES) is greater compared to the dynamic spectral modal analysis according to the magnitude of the earthquakes and the type of soil / Tesis

No description available.

[pt] As previsões de falhas por fadiga tornam-se críticas sob condições multiaxiais de carregamento, uma vez que a complexidade do estado de tensões requer uma análise com base em modelos mais avançados do que aqueles adotados para carregamentos uniaxiais. Neste contexto, alguns critérios foram desenvolvidos para tentar prever a falha de componentes submetidos a carregamentos cíclicos multiaxiais. Um exemplo de componente mecânico sujeito a fadiga multiaxial quando em serviço são os eixos virabrequim de unidades geradoras de plantas termoelétricas. Usualmente projetados segundo o critério de Findley, falhas recentes de eixos virabrequim ocorridas no parque termoelétrico nacional, tem provocado o questionamento da eficiência de tal critério. Desta forma, o presente estudo teve como objetivo analisar a aplicabilidade de seis modelos (Papadopoulos, Findley, Matake, McDiarmid, Carpinteri e Spagnoli e Liu e Mahadevan) de fadiga multiaxial de alto ciclo, baseados no plano crítico, para prever a falha de eixos virabrequim de unidades geradoras. Para aplicação dos modelos, adotaram-se diferentes parâmetros de carregamento (tensão média e defasagem de aplicação das tensões normais e cisalhantes) e propriedades de material (resistência à fadiga), partindo de valores encontrados na literatura. Observou-se uma divergência entre os resultados de cada modelo estudado, sendo uns mais conservadores do que os outros, em função do carregamento e propriedades do material. Entretanto, o modelo de Papadopoulos, com base na facilidade de aplicação e sensibilidade de previsão da falha, mostrou-se mais adequado. / [en] The fatigue failure prediction becomes critical under multiaxial loading conditions, since the complexity of the stress state requires analysis based on models more advanced than those adopted for uniaxial loads. In this context, some criteria were developed in an attempt to predict the failure of components subjected to multiaxial cyclic loads. An example of mechanical component subject to multiaxial fatigue is the crankshaft of thermoelectric plants. It is usually projected according to the Findley criterion. However, recent failures of crankshafts occurring in the national thermoelectric park, put on doubt the efficiency of such criterion. In this way, the present study aimed to analyze the applicability of six models (Papadopoulos, Findley, Matake, McDiarmid, Carpinteri e Spagnoli and Liu e Mahadevan) of high cycle multiaxial fatigue, based on the critical plane, to predict failure on crankshaft of generating units. For the models application, different loading parameters (medium stress and out-of-phase stresses) and material properties (fatigue limit) were adopted, starting from values found in the literature. A divergence between the results of each model was observed, some of them were more conservative than the others, depending on the loading and material s properties. However, the Papadopoulos model, based on easy application and failure prediction sensitivity, proved to be more suitable than the others.

[pt] Estudos recentes têm mostrado que para muitos materiais de Engenharia não existe um limite de fadiga. Numa análise convencional, se admite uma vida infinita em fadiga de alto ciclo quando o material atinge 10(6) - 10(7) ciclos sem a incidência de falhas. Entretanto, em função do desenvolvimento tecnológico atual, a vida-fadiga de inúmeros componentes mecânicos e estruturais pode ultrapassar a fronteira da fadiga de alto ciclo, fazendo com que a avaliação do comportamento em fadiga de altíssimo ciclo (10(7) – 10(12)), tenha se tornado extremamente importante para projetos, por ter estabelecido que uma tensão limite de fadiga não existe em muitos casos. Pesquisas recentes demonstram que a maioria dos materiais, incluindo ligas ferrosas, apresentam falhas em até 10(10) ciclos, com um decréscimo contínuo do limite de fadiga após 10(6) ciclos, o que torna a resistência à fadiga associada com um número de ciclos mais importante do que o próprio limite de fadiga. No regime de altíssimo ciclo de fadiga as trincas se iniciam a partir de defeitos internos do material, como inclusões, gerando mecanismos de iniciação de trincas caraterísticos das superfícies de fratura, tais como olho de peixe (fish-eye), ODA (Optically Dark Area) e FGA (Fine Granular Area). Neste estudo foram usinados corpos de prova do aço DIN 34CrNiMo6, que foram ensaiados entre 10(6) e 10(9) ciclos, sob fadiga ultrassônica do tipo tração-compressão, com frequência de 20 kHz e razão de carregamento -1. Os resultados mostraram que o material tem uma tendência maior a vida-fadiga sob valores baixos de tensão e na superfície de fratura de alguns corpos de prova formação de fish-eye. / [en] Recent studies have shown that for many engineering materials there is no fatigue limit. In a conventional analysis, infinite life in high cycle fatigue is allowed when the material reaches 10(6) - 10(7) cycles without the occurrence of failures. However, due to the current technological development, the fatigue life of several mechanical and structural components can exceed the boundary of high cycle fatigue, making the evaluation of ultra high cyle fatigue behavior (10(7)-10(12)), or fatigue of very high cycle, has become extremely important for projects, because it has established that a stress of fatigue limit does not exist in many cases. Current research has shown that most materials, including ferrous alloys, exhibit failures in up to 10(9) cycles, with a continuous decrease in the fatigue limit after 10(6) cycles, which makes strength fatigue associated with a number of cycles most important than own fatigue limit. In the very high fatigue cycles regime, cracks start from internal defects of the material, such as inclusions, generating a feature mechanisms of crack initiation on the fracture surfaces, such as fish-eye, ODA (Optically Dark Area) and Fine Granular Area (FGA). This study, specimens of DIN 34CrNiMo6 steel were machined and were tested between 10(6) and 10(9) cycles, under ultrasonic fatigue, with a frequency of 20 kHz and a loading ratio of -1. The results showed that the material has a tendency to fatigue life under low stress values and in some fracture sufaces of the specimens the fish-eye formation.

The topic of this thesis is a collection of objects of the postharvest line in the village Horní Moštěnice by the town Přerov. The thesis resolves the time schedule along with the financial plan. In the drawing of the constructional plant is being solved the establishment of the whole construction. Further is it the technical report, site engineering study and a noise study. The thesis is focused on the storage bins, for which is being developed a detailed time schedule, a budget, a drawing of the machine configuration, a technological standard for the assembly of the storage bins, the principles for the construction management, technical management of the constructional plant, control and test plan, safety and health at work protection and the construction site noise.

La presente tesis tiene como objetivo analizar y evaluar la efectividad de reforzar con acero estructural a una edificación existente que no cumple el control de derivas. La edificación a reforzar, ubicada en el distrito de Lince en la ciudad de Lima, cuenta con un área de terreno total de 193m2, con 5 pisos destinados al uso de oficinas y un sistema estructural de pórticos de concreto armado construido en el año 2004. Se exponen todos los sistemas de reforzamiento con acero estructural más utilizados en la actualidad para rigidizar la edificación y que la estructura logre un comportamiento sismorresistente adecuado. El material del reforzamiento será acero estructural ASTM A36. Se verificará las irregularidades que presenta la edificación existente; dado a que la edificación fue construida bajo las especificaciones de la Norma E.030 del 2004, se actualizarán todos los parámetros sísmicos a la más reciente Norma E.030 Diseño Sismorresistente 2018. Se modela la edificación con cada tipo de reforzamiento con acero, se realiza un análisis símico para comprobar que la estructura cumpla con los requisitos especificados en la Norma E.030, y verificar que los desplazamientos laterales relativos de entrepisos (derivas) no superen el límite máximo permitido de 0.007 establecido en la Norma. De esta manera, se optará por el sistema de reforzamiento con acero más efectivo y viable para la edificación. Por último, se verifican todos los elementos estructurales de concreto y se diseña los nuevos elementos de acero implementados a la estructura, bajo la Especificación AISC 360 para acero estructural. / The objective of this thesis is to analyze and evaluate the effectiveness of reinforcing an existing building with structural steel that does not comply with drift control. The building to be reinforced is located in the Lince district in the city of Lima, has a total land area of 193m2. The building consists of 5 floors for office use, it is a structural system of reinforced concrete porches and was built in 2004. All the systems of reinforcement with structural steel most used today are exposed to stiffen the building and that the structure achieves an adequate earthquake-resistant behavior. The reinforcement material will be ASTM A36 structural steel. Irregularities in the existing building will be verified; Since the building was built under the specifications of Standard E.030 of 2004, all seismic parameters will be updated to the most recent Standard E.030 Seismic-resistant Design 2018. The building is modeled with each type of steel reinforcement, a simian analysis is carried out to verify that the structure complies with the requirements specified in Standard E.030, and to verify that the relative lateral displacements of the floors (drifts) do not exceed the limit. maximum allowed of 0.007 established in the Standard. In this way, the most effective and viable steel reinforcement system for the building will be chosen. Finally, all the concrete structural elements are verified and the new steel elements implemented to the structure are designed, under the AISC 360 Specification for structural steel. / Tesis

Purpose: The purpose of this study has been to investigate the essentials of being able to incorporate high-strength steels (460 MPa and beyond) for structural elements in buildings. As of late, structural steels with a yield point of 355 MPa have been considered standard and have been for the past decade. One of the problems that occur with an increased yield point, is that deflection of structural elements increases, as the Young’s modulus does not increase with increasing yield point. Welding, stability, behavior during fire, and fatigue are also subjects of interest. Method: The study was conducted through several courses of action: a literature review covering the latest research of high-strength steels within the sought-after area of interest, followed by calculations of a truss resting on two columns, being subject to bending moment and compressive force, in both 355 MPa and 700 MPa, in order to review the differences that occur and how they can be counteracted. Lastly, interviews were carried out, where structural engineers gave their thoughts and experiences on the matter at hand. Results: The results show that welding is one of the largest hurdles with being able to utilize high-strength structural steels, though there are newer, more promising methods of welding which can be used, such as electron beam welding. Regarding structural integrity and buckling of structural elements, high-strength steel can be used for trusses, where the structural members are mainly being pulled, opposed to being subject to compressive force. This was shown with the performed calculations, during the interviews, and by the literature overview. Conclusions: The general conclusions of the study is that for welding, further research, education, and training is required for all concerned parts, such as the structural engineers and the on-site welders, which will increase the knowledge regarding how welding of high-strength steels should be performed, but also raise awareness about newer and more modern methods. Fire behavior for high-strength steels are a higher risk factor that should be treated and executed with higher degrees of caution by engineers. Reduction factors for fire affected steel construction elements should be corrected to fit the behavior for high-strength steels as well, as they differ from the current Eurocode 3 for lower class steels. Problems with instability can be counteracted by utilizing the steel in pulled structural members, such as trusses and struts. Lastly, for high-strength steels to be used more widely, structural engineers and manufacturers need to work together for any of the two to profit, as low production rates are costly.