Made available in DSpace on 2015-04-22T22:08:47Z (GMT). No. of bitstreams: 1 Marcia Almeida de Amaral Arcos da Silva.pdf: 5304856 bytes, checksum: eae7bcdf9eec417c3e35e203f7ad60d2 (MD5) Previous issue date: 2012-06-29 / Some studies have shown that the joint use of concrete and wood for composite structures is a viable solution for rural roads, showing a satisfactory performance with good durability, may become viable for roads in the Amazonas State. In fact the need of utilization of bridges with small and medium spans is very large and many times the nonexistence of this kind of bridge can affect the development of a municipality. In addition, the poor conservation of theses bridges can bring discomfort and risk to the users. The composite system presents a good structural performance, is an economic system when compared with others alternatives of construction as steel and concrete, and offers good durability. However, the efficiency of this structural system should be ensured by means of a link on the interface of the materials. On the other hand, the bridges are exposed to severe conditions of weather and load requiring careful studies to evaluate with more accuracy the mechanisms of connections between the concrete and wood, as well as the behavior of the composite structure during its useful life. In this work a survey about the constructive systems of the bridges used in the city of Manaus-AM was conducted. It was also evaluated the type of wood used in the construction of these bridges, and it was verified that there is poor utilization of the timber in bridges yet. After that, shear tests in composite specimens of wood and concrete with connection system of the type X , formed by screws of type CS100900, were carried out. Bending tests on composite beams with cross section T with the same connection system also were carried out. The experimental results from the bending tests were compared with the results obtained by analytical model of Mohler, which is presented in Eurocode 5/1993 standard and these showed a good agreement to service loads. Therefore, the composite system of wood and concrete with metallic connection is an alternative for the bridges of wood used in rural areas of Brazil and mainly in Manaus city where there is a huge need by use of this composite system. / Estudos têm mostrado que a utilização conjunta do concreto e da madeira para a obtenção de estruturas mistas é uma solução viável para pontes de vias rurais, apresentando um desempenho satisfatório com uma boa durabilidade, podendo, tornar-se viável também para estradas vicinais no estado do Amazonas. De fato a necessidade da utilização de pontes de médios e pequenos vãos é tanta que muitas vezes a não existência destas pode comprometer o desenvolvimento de um município. Além disso, quando existem, em alguns casos, sua má conservação pode trazer desconforto e risco aos seus usuários. O sistema misto apresenta ótimo desempenho estrutural, é um sistema econômico quando comparado com outras alternativas de construção como o aço e o concreto e apresenta boa durabilidade. Porém, a efetivação desse sistema estrutural deve ser assegurada por meio de uma ligação na interface dos materiais. Por outro lado, as pontes são expostas a condições severas de intemperismo e carregamento, necessitando, desse modo, de estudos cuidadosos para que se possa avaliar com maior precisão os mecanismos da ligação, bem como o comportamento da estrutura mista em toda sua vida útil. No presente trabalho de pesquisa foi realizado um levantamento sobre os sistemas de pontes utilizados na cidade de Manaus‐AM assim como do tipo de madeira utilizado na construção destas, a partir dos quais se constatou que ainda existe má utilização da madeira em pontes. Na sequencia foram realizados ensaios de cisalhamento em corpos de prova mistos de madeira e concreto com sistema de conexão em X composto por parafusos do tipo CS100900, além de ensaios de flexão em vigas mistas com seção T utilizando-se do mesmo sistema de conexão em X . Os resultados experimentais de flexão das vigas foram comparados com os resultados analíticos obtidos pelo Modelo de Mohler, que está apresentada no Eurocode 5/1993 e estes apresentaram uma boa concordância para carregamentos de serviço. Portando, como uma alternativa para solução da má utilização da madeira, neste caso, o sistema de conexão misto madeira e concreto proposto consiste numa excelente alternativa para a utilização em pontes da zona rural de todos os municípios brasileiros, principalmente, em Manaus onde existe uma carência declarada pela utilização desse sistema.

This thesis describes part of the work associated with Project 0-6719 sponsored by the Texas Department of Transportation (TxDOT). The primary objective of the project is to examine the feasibility of strengthening older continuous multi-span steel girder bridges through the use of post-installed shear connectors. Bridges potentially eligible for retrofit have noncomposite floor systems, where the concrete slab is not attached to the steel girders with shear connectors. Many of these bridges were designed in the 1950's and 1960's for loads smaller than the standard design loads used today. A secondary objective of the project, and the main focus of this thesis, is to examine the design of post-installed shear connectors for fatigue. Of particular interest in this study is the adhesive anchor, given its convenient installation procedure but relatively poor fatigue performance in previous tests. The objectives of this thesis were to quantify the fatigue strength of the adhesive anchor, as well as quantify the shear force and slip demands on adhesive anchors in realistic bridge conditions. In regards to the first objective, twenty-six direct shear fatigue tests were performed on adhesive anchors. Each test was conducted on a single adhesive anchor in order to capture its individual cyclic load-slip behavior. Results indicate that adhesive anchors have considerably higher fatigue strength than conventional welded shear studs, making partial composite design feasible in the strengthening of older steel bridges. In regards to the second objective, analytical and computational studies were conducted on composite beams with adhesive anchors. Results show that the shear force and slip demands are typically smaller than the endurance limits determined from direct-shear testing. This suggests that fatigue failure of adhesive anchors under service loads may not be a primary concern. Based on the results, preliminary recommendations for the design of adhesive anchors for fatigue are provided. / text

This research investigates prefabricated light-gauge steel and concrete panels using reliable and commercially viable shear connectors. An analytical and experimental investigation was undertaken to study the flexural behaviour of light-gauge steel and concrete composite panels under uniform pressure. Normalweight and lightweight concrete panels were fabricated by embedding 16-gauge 41 mm x 203 mm steel channel sections (running parallel to each other) to a depth of 38 mm into a 64 mm thick concrete slab. Push-out tests were also conducted to evaluate the efficiency of three types of shear connection mechanism; natural surface bonding, predrilled holes, and punched holes. Only two types of shear connectors (predrilled holes and punched holes) were used in the full-scale panel specimens. Results show that the predrilled holes and punched holes provide full shear transfer between the steel and concrete. The ultimate load carrying capacity of the lightweight concrete panels exhibited similar behaviour to the normalweight concrete panels. All the panels exhibited good load carrying capacity and ductility, and satisfied the serviceability limit state of deflection. Thus, the proposed panels present a potential for a commercially viable composite floor system for building construction utilizing a maximum span of 2330 mm.

Made available in DSpace on 2015-03-26T13:28:02Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1212266 bytes, checksum: 4433ea571934263da47083bffd54b46a (MD5) Previous issue date: 2011-04-06 / In recent years, several investigations on shear connectors in flat steel plate with holes have been conducted, in order to application in composite structures of steel and concrete. Although several experimental programs have been implemented in several countries, the behavior of these connections remains an object of study. In this work, we make a research on the contribution of openings in global strength of two types of connectors in perforated steel plate: the Perfobond, designed by German company Leonhardt, Andra und Partners (LAP) and Crestbond, designed by a group of brazilian researchers from UFV and UFMG. From the experimental results obtained by other authors, several semiempirical models were studied, based on some reasonable assumptions about the mechanisms that determine the resistant behavior of the connection, considering the effect of concrete dowels in the connector s openings. These new models are compared with previously proposed by some authors. For this we used experimental results of tests conducted in Brazil, Portugal and Canada. The analysis carried out allowed to obtain equations of resistance better than the existing ones, capable of estimating the resistance of Crestbond and Perfobond connectors with light weight concrete and normal concrete, as well as a better understanding of the structural behavior of those connectors. / Nos anos recentes, diversas investigações sobre conectores de cisalhamento em chapa plana de aço com perfurações vêm sendo conduzidas, com vistas à aplicação em estruturas mistas de aço e concreto. Embora vários programas experimentais tenham sido executados em diversos países, o comportamento dessas conexões ainda permanece como objeto de estudo. Neste trabalho, faz-se uma investigação sobre a contribuição das aberturas na resistência global de dois tipos de conectores em chapa perfurada: o Perfobond, criado pela empresa alemã Leonhardt, Andrå und Partners (LAP) e o Crestbond, criado no Brasil por pesquisadores da UFV e da UFMG. A partir dos resultados experimentais obtidos por outros autores, diversos modelos semiempíricos foram estudados, com base em algumas hipóteses razoáveis sobre os mecanismos resistentes que determinam o comportamento da conexão, tendo em vista o efeito de pino do concreto nas aberturas dos conectores. Esses novos modelos são comparados com outros anteriormente propostos por alguns autores. Para isso foram utilizados resultados experimentais de ensaios realizados no Brasil, em Portugal e no Canadá. As análises realizadas possibilitaram a obtenção de equações de resistência mais adequadas que as já existentes, capazes de estimar a resistência dos conectores Perfobond e Crestbond em concreto normal e em concreto leve, bem como um melhor entendimento do comportamento estrutural desses conectores.

In steel-concrete composite construction, headed stud shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface. Present knowledge of the load-slip behavior of the shear stud in composite beam is limited to data obtained from the experimental push-off tests. A finite element model to simulate the structural behavior of headed stud shear connector in steel-concrete composite beam is described in the chapter. The model is based on finite element method and takes into account linear and nonlinear behavior of the materials. The model has been validated against test results and compared with data given in the current Code of Practices, for which both demonstrate the accuracy of the model used. Parametric studies using the model to investigate variations in concrete strength and shear stud diameter are also discussed in the chapter. The model takes into account the linear and nonlinear material properties of the concrete and shear stud. The FE results compare well with the experimental push-off test results and specified data from the codes. The FE model accurately predicts the mode of failure.

No / This paper presents the experimental and numerical investigation into the behaviour of headed shear studs in composite beams with profiled metal deck flooring. A new single-sided horizontal push test arrangement is proposed to evaluate the shear capacity of the headed shear connectors in pairs with metal deck profiled sheeting. The characteristic resistance obtained from the horizontal push test is compared with Eurocode 4. A three-dimensional finite element model was developed using general purpose finite element program ABAQUS/Explicit. The shear connector capacity, load-slip behaviour and failure modes are validated against experimental results and close correlations were obtained.

yes / This paper presents an experimental study on shear strength, stiffness and ductility of demountable shear connectors in metal decking composite slabs through push-off tests. Twelve full-scale push-off tests were carried out using different concrete strength, number of connectors and different connector diameter. The experimental results showed that the demountable shear connectors in metal decking composite slabs have similar shear capacity and behaviour as welded shear studs and fulfilled the minimum ductility requirement of 6mm required by Eurocode 4. The shear capacity was compared against the prediction methods used for the welded shear connections given in Eurocode 4, AISC 360-10, ACI 318-08 and method used for bolted connection in Eurocode 3. It was found that the AISC 360-10 method overestimated the shear capacity while the ACI 318-08 method underestimated the shear capacity of specimens with single shear connector per trough. The Eurocodes method was found to provide a safe prediction for specimens with single and pair demountable connectors per trough. In addition, prediction methods given in both AISC 360-10 and ACI 318-08 for welded shear studs overestimated the shear capacity of specimens with 22 mm diameter demountable connectors that failed in concrete crushing. / PhD work from EPSRC studentship

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no / Precast concrete floors are widely used in building construction, but there is little detailed design guidance on their application in steel-framed buildings. Traditionally the steel beams have been designed to support the precast slabs on their top flange. However, there are an increasing number of composite frames and slim floor constructions where the precast slabs are designed to interact structurally with the steel frame. Composite action can be developed by welded shear connectors attached to the steel beams and by transverse reinforcement; however, this form of construction is currently outside the provisions of the current codes of practice. This paper discusses some of the particular issues that affect this form of construction, and presents design guidance using the Eurocode methodology.

Yes / This paper presents experimental and numerical investigation on an innovative composite floor system with deconstructability. In this system, a composite slab formed with metal profiled decking is connected to a steel beam using demountable shear connectors. A series of push tests was conducted to investigate the behaviour of this form of shear connectors. In addition to the push tests, a full-scale composite beam was tested to failure in the laboratory under a number of cycles of monotonic loading. For direct comparison, a similar composite beam test was conducted using same section size, concrete strength, but using the conventional welded headed stud connectors. Test results showed that the behaviour of the composite beam with demountable shear connectors is comparable with the specimen with welded shear connectors. After the test was terminated, the demountable shear connectors were unfastened and the composite floor can be easily lifted off from the steel beam. Test result showed that these demountable shear connectors possess high ductility in comparison with the equivalent welded shear connectors. Simple design rules currently use in Eurocode 4 for the welded shear connections and Eurocode 3 for bolts are proposed to predict the shear resistance of this form of demountable shear connectors.