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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Автоматизация расчета на продавливание и проектирование поперечной арматуры плит перекрытия на примере МФК «Университетский» по ул. Мира-Библиотечная-Комсомольская г. Екатеринбурга : магистерская диссертация / Automation of calculation for punching and design of transverse reinforcement of floor slabs on the example of MFC "Universitetsky" on the street. Mira-Library-Komsomolskaya, Yekaterinburg

Исупов, Н. С., Isupov, N. S. January 2022 (has links)
Автоматизация проектирования несущих конструкций – одно из стремительно развивающихся направлений в области BIM моделирования. В работе рассмотрены методики армирования железобетонных конструкций с применением информационной модели здания. По результатам исследования написаны два скрипта для среды визуального программирования Dynamo для автоматизации расчета на продавливание. / Automation of the design of load-bearing structures is one of the rapidly developing areas in the field of BIM modeling. The paper considers methods of reinforcing reinforced concrete structures using an information model of a building. According to the results of the study, two scripts were written for the Dynamo visual programming environment to automate the calculation for punching.
52

Punching shear of concrete flat slabs reinforced with fibre reinforced polymer bars

Al Ajami, Abdulhamid January 2018 (has links)
Fibre reinforcement polymers (FRP) are non-corrodible materials used instead of conventional steel and have been approved to be an effective way to overcome corrosion problems. FRP, in most cases, can have a higher tensile strength, but a lower tensile modulus of elasticity compared to that of conventional steel bars. This study aimed to examine flat slab specimens reinforced with glass fibre reinforced polymer (GFRP) and steel bar materials for punching shear behaviour. Six full-scale two-way slab specimens were constructed and tested under concentric load up to failure. One of the main objectives is to study the effect of reinforcement spacing with the same reinforcement ratio on the punching shear strength. In addition, two other parameters were considered, namely, slab depth, and compressive strength of concrete. The punching shear provisions of two code of practises CSA S806 (Canadian Standards 2012) and JSCE (JSCE et al. 1997) reasonably predicted the load capacity of GFRP reinforced concrete flat slab, whereas, ACI 440 (ACI Committee 440 2015) showed very conservative load capacity prediction. On the other hand, a dynamic explicit solver in nonlinear finite element (FE) modelling is used to analyse a connection of column to concrete flat slabs reinforced with GFRP bars in terms of ultimate punching load. All FE modelling was performed in 3D with the appropriate adoption of element size and mesh. The numerical and experimental results were compared in order to evaluate the developed FE, aiming to predict the behaviour of punching shear in the concrete flat slab. In addition, a parametric study was created to explore the behaviour of GFRP reinforced concrete flat slab with three parameters, namely, concrete strength, shear load perimeter to effective depth ratio, and, flexural reinforcement ratio. It was concluded that the developed models could accurately capture the behaviour of GFRP reinforced concrete flat slabs subjected to a concentrated load. Artificial Neural Networks (ANN) is used in this research to predict punching shear strength, and the results were shown to match more closely with the experimental results. A parametric study was performed to investigate the effects of five parameters on punching shear capacity of GFRP reinforced concrete flat slab. The parametric investigation revealed that the effective depth has the most substantial impact on the load carrying capacity of the punching shear followed by reinforcement ratio, column perimeter, the compressive strength of the concrete, and, the elastic modulus of the reinforcement.
53

Energy Release Rate Based Mechanism for the wear of Punches in Precision Blanking of High Strength Steel

Singh, Siddarth 27 July 2011 (has links)
No description available.
54

Effect of shear cutting on metal fatigue

Gustafsson, David January 2024 (has links)
Lightweighting of automotive and heavy-duty vehicle components is an important task that does not need any further motivation or background. It can be read in a large part of the technical papers in the field. A common approach for finding lighter solutions is to increase the material grade while decreasing the material thickness. Often in combination with design changes. For perfectly smooth components this is not an issue, but when cut edges from manufacturing processes are present the situation changes. One topic to address is that increased material grade often means increased notch and surface damage sensitivity. This has implications both on forming and fatigue. The reason for selecting a higher strength material is to allow for higher stresses in design. It has however been shown that for a given stress level the fatigue performance of a higher strength material could be worse than for a lower strength counterpart if punched holes or trimmed edges are present. This means that in the search of lower weight there is a risk of increasing stresses, and at the same time selecting a material that is less suited to handle this increase. Hence, engineers and developers are put in a position where these effects must be quantified to find the most efficient solution. This quantification is a cumbersome and expensive task, often including a considerable amount of testing. Important sources of fatigue life reduction in this context are the residual stresses in the loading direction and the surface roughness in the cut edge. This thesis aims to present an overview of metal fatigue in the context of shear cut components. Necessary knowledge regarding the shear cutting process is provided along with a description of numerical methods and considerations for process simulations. These findings are then applied to the presented papers where the first introduces a simplified approach for numerical simulation of shear cutting to obtain residual stresses. In this approach the simplification mainly lies in the failure model calibration. The second paper studies the possibility of using the obtained residual stresses together with measured values of surface roughness to quantify fatigue life reduction of shear cut specimens.
55

Punching Holes in the Cloud: Direct Communication between Serverless Functions Using NAT Traversal

Moyer, Daniel William 04 June 2021 (has links)
A growing use for serverless computing is large parallel data processing applications that take advantage of its on-demand scalability. Because individual serverless compute nodes, which are called functions, run in isolated containers, a major challenge with this paradigm is transferring temporary computation data between functions. Previous works have performed inter-function communication using object storage, which is slow, or in-memory databases, which are expensive. We evaluate the use of direct network connections between functions to overcome these limitations. Although function containers block incoming connections, we are able to bypass this restriction using standard NAT traversal techniques. By using an external server, we implement TCP hole punching to establish direct TCP connections between functions. In addition, we develop a communications framework to manage NAT traversal and data flow for applications using direct network connections. We evaluate this framework with a reduce-by-key application compared to an equivalent version that uses object storage for communication. For a job with 100+ functions, our TCP implementation runs 4.7 times faster at almost half the cost. / Master of Science / Serverless computing is a branch of cloud computing where users can remotely run small programs, called "functions," and pay only based on how long they run. A growing use for serverless computing is running large data processing applications that use many of these serverless functions at once, taking advantage of the fact that serverless programs can be started quickly and on-demand. Because serverless functions run on isolated networks from each other and can only make outbound connections to the public internet, a major challenge with this paradigm is transferring temporary computation data between functions. Previous works have used separate types of cloud storage services in combination with serverless computing to allow functions to exchange data. However, hard-drive--based storage is slow and memory-based storage is expensive. We evaluate the use of direct network connections between functions to overcome these limitations. Although functions cannot receive incoming network connections, we are able to bypass this restriction by using a standard networking technique called Network Address Translation (NAT) traversal. We use an external server as an initial relay to setup a network connection between two functions such that once the connection is established, the functions can communicate directly with each other without using the server anymore. In addition, we develop a communications framework to manage NAT traversal and data flow for applications using direct network connections. We evaluate this framework with an application for combining matching data entries and compare it to an equivalent version that uses storage based on hard drives for communication. For a job with over 100 functions, our implementation using direct network connections runs 4.7 times faster at almost half the cost.
56

Zařízení pro děrování profilů / Equipment for punching profiles

Hudeček, Jan January 2016 (has links)
This thesis is focused on the construction of punching device for punching continuously extruded plastic profile. This device is part of a larger production line. The theoretical part of this work will be focused in an introduction to plastic extrusion, cutting, molding properties and market research with punched plastic profiles. The practical part will deal with the product description, production line and the structural design of the entire machine itself including calculations. Part of this work are also drawing of selected parts and a 3D model.
57

Punching shear behaviour of GFRP-RC slab-column edge connections with high strength concrete and shear reinforcement

Mostafa, Ahmed 17 November 2016 (has links)
In this thesis the experimental results of seven full-scale glass fiber-reinforced polymer (GFRP) reinforced concrete (RC) slab-column edge connections are presented. The dimensions of the slabs were 2,800×1,550×200 mm with a square column measuring 300×300×2,200 mm. The test connections were divided into two series. Series I included three connections investigating the effect of flexural reinforcement ratio (0.90, 1.35 and 1.80%) when high strength concrete (HSC) is used, while Series II included four connections investigating the effect of GFRP shear reinforcement type and pattern on normal strength concrete (NSC) connections. Test results showed that increasing the reinforcement ratio increased the punching capacity and the post-cracking stiffness of the HSC connections. Furthermore, the use of headed studs and corrugated bars increased the punching capacity and the deformability of the NSC connections. Test results were compared to the predictions of the Canadian and American design provisions for FRP-RC structures. / February 2017
58

Punção em lajes cogumelo de concreto armado: análise experimental e numérica. / Punching in reinforced concrete flat slabs: experimental and numerical analysis.

Trautwein, Leandro Mouta 12 April 2006 (has links)
Este trabalho descreve uma pesquisa experimental de lajes cogumelo de concreto armado com armadura de cisalhamento, sem envolver a armadura de flexão. Onze lajes cogumelo quadradas de concreto com 200 mm de espessura e 3000 mm de lado, com uma área central carregada de 200 mm de lado, foram testadas até a ruptura. O principal objetivo dos ensaios foi investigar a eficiência de se utilizar esse tipo de armadura de cisalhamento sem envolver a armadura de flexão. Todas as lajes romperam por punção, com cargas de ruptura superiores em até 110%, em relação às cargas de ruptura em lajes similares sem armadura de cisalhamento, demostrando a eficiência da armadura. Foram realizadas também simulações numéricas utilizando modelos axissimétricos e tridimensionais, de lajes cogumelo de concreto armado, com o objetivo de reproduzir numericamente alguns resultados obtidos por pesquisadores e documentados na literatura, validando a parte experimental e a modelagem numérica. As simulações numéricas nãolineares foram realizadas com programa DIANA, e o modelo de fissuração do concreto adotado foi o distribuído (smeared crack). Foram analisados os resultados de cargas últimas e tipos de ruptura, fissuração, deformações nas armaduras e no concreto e as curvas carga x deslocamento. / This work reports experimental research of reinforced concrete flat slabs with use of shear reinforcement not embracing the flexural reinforcement. Eleven square reinforced concrete flat slabs with 200 mm thickness and 3000 mm side lengths, with a square central column of 200mm of side, were tested up to failure. The main objective was to investigate the efficiency of using the mentioned shear reinforcement. All slabs failed by punching and the ultimate loads were superior in up to 110% in relation to slabs without shear reinforcement, demonstrating the efficiency of the reinforcement. The numerical simulations using axisymmetric and three dimensional analyses, of reinforced concrete flats slabs, were carried out with the objective of reproducing some experimental results reported by different investigators, validating the experimental part and also the numerical modelling . The numerical simulations were performed with the software package DIANA, adopting the smeared crack approach to reproduce the concrete behaviour under shear and tension. The evaluated results were mode of failure, strain in steel and loaddeflections curves.
59

Verificações da punção e da estabilidade global em edifícios de concreto: desenvolvimento e aplicação de recomendações normativas / Punching shear and global stability of concrete buildings: development and application of code provisions

Lima, Juliana Soares 20 April 2001 (has links)
Neste trabalho, são estudas as verificações da punção global segundo a revisão da NBR 6118. A partir da análise dos fenômenos físicos e com base nos estudos teóricos realizados, são feitas sugestões para serem contornadas algumas omissões da Norma. Também são propostas complementação que facilitem o entendimento das novas recomendações e, ainda, modificações que melhorem seus resultados. Sugerem-se métodos simplificados relacionados à punção excêntrica, e propõem-se algumas alterações quanto ao uso do &#947z como coeficiente majorador na avaliação da estabilidade global. Observa-se que as verificações, apesar de mais trabalhosas, apresentam melhorias significativas em relação à NBR 6118 (1978), mostrando-se mais detalhadas e eficientes. Ainda assim, considera-se importante a introdução de algumas complementações, como aquelas sugeridas neste trabalho. / This work presents an overview of the requirements for punching shear and global stability of buildings in the draft Brazilian Code for concrete structures. Suggestions are made for fulfilling some omissions of the Code, based on theoretical studies and physical phenomena analysis. Some complements and changes are also proposed to facilitate the understanding of the new recommendations and to improve their results. Simplified methods related to the eccentric punching and modifications in the use of &#947z as a first order effects magnifier are suggested. It is concluded that the new provisions are more detailed and efficient, presenting significant improvements on both topics, especially when compared to NBR 6118 (1978). Nevertheless, it is considered important the introduction of some complements, as those suggested in this work.
60

Análise dos mecanismos resistentes e das similaridades de efeitos da adição de fibras de aço na resistência e na ductilidade à punção de lajes-cogumelo e ao cisalhamento de vigas de concreto. / Analysis of resistant mechanisms and similarities of the addition effect of steel fibers on strength and ductility to both the punching shear of flat slabs and the shear of concrete beams.

Holanda, Kristiane Mattar Accetti 02 October 2002 (has links)
Um dos principais problemas das lajes-cogumelo refere-se à ruína por puncionamento da ligação laje-pilar. Esta forma de ruína deve ser evitada, proporcionando-se às lajes as melhores condições para o desenvolvimento de mecanismos de escoamento das armaduras e de ruína por flexão, antes da ocorrência da ruína por cisalhamento. A introdução de fibras de aço em elementos de concreto submetidos a solicitações tangenciais proporciona melhoria de desempenho, seja pelo aumento da capacidade resistente, seja pela alteração da forma de ruína. Pretende-se contribuir com o avanço do conhecimento sobre o assunto, explorando aspectos como a análise das similaridades dos efeitos da adição de fibras de aço na resistência e na ductilidade de lajes-cogumelo à punção, com aqueles que se observam no cisalhamento de vigas prismáticas análogas. Abordam-se os casos de ligações laje-pilar interno sem armadura de punção, variando-se a resistência do concreto, a taxa e o tipo de fibra utilizado. A partir dos resultados experimentais, verificou-se que existe uma similaridade de comportamento estrutural entre esses dois elementos e concluiu-se que é possível utilizar ensaios de cisalhamento em vigas prismáticas para se obter indicadores a serem utilizados nos ensaios de punção de lajes. Foi efetuada uma análise da adaptabilidade de modelos teóricos existentes sobre cisalhamento em vigas e punção em lajes, com vistas à consideração do efeito da adição de fibras de aço ao concreto. Com base nesses modelos, foram estabelecidos critérios quantitativos para avaliação da resistência e da ductilidade das ligações laje-pilar. / One of the main problems of flat slabs concerns the punching shear failure of the slab-column connection. This form of failure must be avoided, providing flat slabs with the best conditions for the development of yielding mechanisms of the flexural reinforcement before the occurrence of shear failure. The addition of steel fibers to concrete elements subjected to tangential stress provides performance improvement, by either the resistant capacity increase or the failure mode alteration. It is intended to contribute to the advance of the subject knowledge, by exploring aspects as the analysis of similarities of the steel fiber addition effects on both strength and ductility of flat slabs to punching shear with those observed in the shear of analogous prismatic beams. The cases approached include internal slab-column connections without shear reinforcement, and the variables investigated included concrete strength, fiber volume and type of steel fiber. From the experimental results, it was possible to verify that there exists a similarity of structural behavior between these two elements and the shear tests in prismatic beams can be used to get indicators to be utilized in punching shear tests of flat slabs. An adaptability analysis of the existing theoretical models on shear in beams and punching shear in flat slabs was carried out in order to consider the steel fibers addition effect on the concrete. Based on these models, quantitative criteria for the evaluation of both strength and ductility of the slab-column connections were established.

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