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Ghavam-Shahidy, Hamid. "Lightweight aggregate reinforced concrete deep beams." Thesis, University of Dundee, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503556.
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Green, Jeremy Robert, and Jeremy Robert Green. "Behaviour of reinforced concrete deep beams." Master's thesis, University of Cape Town, 1985. http://hdl.handle.net/11427/23219.
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Twenty five model beams were progressively loaded to failure in order to investigate the influence of the following variables on the behaviour of reinforced concrete deep beams : i) Concrete compressive strength ii) Reinforcement iii) Geometry. The model beams were all of 1500mm span, with a depth of 750mm. This span to depth ratio of 2 corresponds to the upper limit, to which the recommendations for deep beam design applies, as provided by many current codes of practice. Methods currently in use for the design of reinforced concrete deep beams were reviewed and compared. The experimental results were compared with the predictions of these design methods. This comparison revealed a large lack of agreement in the predictions of the cracking and ultimate strengths of deep beams.
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Tian, Shichuan. "Shear behaviour of ferrocement deep beams." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/shear-behaviour-of-ferrocement-deep-beams(88ca7d6e-e285-4ec6-8741-da3f89047bde).html.
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This thesis presents the results of an experimental, numerical and analytical study to develop a design method to calculate shear resistance of flanged ferrocement beams with vertical mesh reinforcements in the web. Two groups of full-scale testing were conducted comprising of three I beams and four U beams. The I beams had the same geometry and reinforcement arrangements, but differed in the matrix strength or shear span to depth ratio. The U beams differed in web and flange thickness, reinforcement arrangements, matrix strength and shear span to depth ratio. The experimental data were used for validation of finite element models which had been developed using the ABAQUS software. The validated models were subsequently employed to conduct a comprehensive parametric study to investigate the effects of a number of design parameters, including the effect of matrix strength, shear span to depth ratio, cross sectional area, length of clear span, volume fraction of meshes and amount of rebar. The main conclusion from the experiments and parametric studies were: shear failure may occur only when the shear span to depth ratio is smaller than 1.5; the shear strength may increase by increasing the matrix strength, volume fraction of meshes, cross sectional area and amount of rebar. The main type of shear failure for I beams was diagonal splitting while for U beams it was shear flexural. Based on the results from the experimental and numerical studies, a shear design guide for ferrocement beams was developed. A set of empirical equations for the two different failure types and an improved strut-and-tie were proposed. By comparison with the procedures currently in practice, it is demonstrated that the methodology proposed in this thesis is likely to give much better predictions for shear capacity of flanged ferrocement beams.
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Ismail, Kamaran Sulaiman. "Shear behaviour of reinforced concrete deep beams." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/12600/.
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RC deep beams are key safety critical structural systems carrying heavy loads over short span, such as transfer girders in tall buildings and bridges. Current design provisions in codes of practice fail to predict accurately and reliably the shear capacity of RC deep beams and in some cases they are unsafe. This work aims to develop a better understanding of the behaviour of RC deep beams and governing parameters, and to improve existing design methods to more accurately predict the shear capacity of such members. An extensive experimental programme examining 24 RC deep beams is carried out. The investigated parameters include concrete strength, shear span to depth ratio, shear reinforcement and member depth. To develop a better insight on the distribution and magnitude of developed stresses in the shear span, finite element analysis is also performed. The microplane model M4 is implemented as a VUMAT code in ABAQUS to represent the behaviour of concrete in a more reliable manner and validated against experimental tests on RC deep beams. This model is utilised in a parametric study to further investigate the effect of concrete strength, shear span to depth ratio and shear reinforcement. The experimental and numerical results show that concrete strength and shear span to depth ratio are the two most important parameters in controlling the behaviour of RC deep beams, and that shear strength is size dependent. The analysis also shows that minimum amount of shear reinforcement can increase the shear capacity of RC deep beams by around 20% but more shear reinforcement does not provide significant additional capacity. A lateral tensile strain based effectiveness factor is proposed to estimate the strength of the inclined strut to be used in strut-and-tie model. Additionally, node factors to estimate the developed strength in different type of nodes are proposed. The proposed model is evaluated against a large experimental database and the results show that it yields more accurate and reliable results than any of the existing models. The model is characterized by the lowest standard deviations of 0.26 for both RC deep beams with and without shear reinforcement and accounts more accurately for all influencing parameters.
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Tang, Chi Wai John. "Reinforced concrete deep beams : behaviour, analysis and design." Thesis, University of Newcastle Upon Tyne, 1987. http://hdl.handle.net/10443/626.
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The work described in this thesis is concerned with the behaviour, analysis and design of reinforced concrete beams. A brief historical review of the methods of analysis on deep beams is given. The current major codes of practice and design manuals associated with reinforced concrete deep beams are reviewed. This study has been useful in identifying the limitations of the current design documents on the subject of deep beams. Because of the acute shortage of information regarding buckling, web-opening and combined loading, three test programmes are performed to provide experimental evidence on these topics. Their behaviour is examined in terms crack developments, crack patterns, modes of failure, in-plane and lateral displacements, ultimate loads, strains and stresses. The ultimate buckling strength of the slender deep beams without web-openings are analysed using the methods described in the CIRIA Guide (1977). Adopting the same methods in the guide, an attempt has been made to analyse the buckling strength of deep beams with web-openings. Based on the structural idealization of Kong et al (1973), a modified approach is proposed for the ultimate shear strength of deep beams with web-openings. In addition, the CIRIA ultimate shear interaction equation for deep beams under combined top and bottom loadings is studied and an equation is proposed for the uniformly distributed loading cases. Finally, based upon these findings, some design recommendations are given.
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Chemrouk, Mohamed. "Slender concrete deep beams : behaviour, serviceability and strength." Thesis, University of Newcastle upon Tyne, 1988. http://hdl.handle.net/10443/3103.
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Reinforced concrete deep beams have useful applications in construction. However, their design is not yet covered by the British Standard BS 8110: 1985 which explicitly states that "for the design of deep beams, reference should be made to specialist literature". A selection of literature on deep beams is considered. First, the major works that have led to design recommendations are reviewed. Then, the current major codes and manuals covering deep beams, namely the CIRIA Guide, the European CEB-FIP model code, the American ACI(318-83) (revised 1986) code and the Canadian CAN3-A22.3-MB4 code are outlined; worked examples are given in order to illustrate their practical applications and compare their different approaches to deep beam design. The purpose of this literature review was to define the deep beam problem and identify the major questions still remaining unanswered together with the limitations of the present design documents on the subject. The nature of diagonal cracking in slender deep beams has recently raised a question as to the application of the shear-strength equation in cl.3.4.2 of the CIRIA Deep Beam Guide. The effectiveness of web reinforcement on serviceability and strength of deep beams in general is also an area where strong disagreement exists. A testing programme, consisting of 15 beams of height/thickness ratios ranging from 20 to 50 and grouped in 3 different series, was performed to provide information on these two areas. The main variables were the height/thickness ratio and the quantity and arrangement of web steel. The beams were tested under concentrically applied two point-loads. Based on the test results and observations, modifications are given for the CIRIA equation and other formulae derived from stocky deep beam tests to be used in slender ones for analysis and design purposes. A new formula is also proposed for the prediction of the ultimate shear capacity. The stability of deep beams is another area which has received less attention in the past by researchers and designers who often avoided the problem by opting for stocky sections. To quote from the CIRIA Guide "as a possible criterion of failure, buckling can not be disregarded". However, information on such topic is very scarce in the literature. Currently, the only documents that provide design guidelines for buckling are the CIRIA Guide and the Portland Cement Association Design Aid, both of which are based on theoretical studies and engineering judgement. An experimental testing programme, consisting of 7 large scale beam-panels with height/thickness ratios in the range of 20 to 70 and a constant span/depth ratio of 1.0, provided buckling data against which the reliability of the two design documents was assessed. These tests confirmed that both documents offer a safe buckling design with the CIRIA Guide being too conservative. Although deep beams are frequently continuous over several spans, very little published data exist for such beams. For this purpose, 12 two-span continuous concrete deep beams with span/depth ratios less than 1.0 and having different quantities and arrangements of web reinforcement were tested under two point-loads. The specimens were heavily instrumented to obtain as much information as possible about the behaviour of the beams at each stage of loading. Applied loads and reactions were among the measurements made and enabled the actual bending moment distribution to be determined and compared to that of corresponding continuous shallow beams. Based on the test results and observations and in the light of other published work, recommendations are given for the bearing, shear and flexural design of continuous deep beams.
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Ahmad, BouSaleh. "Effects of anchorage details on response of deep beams." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98946.
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As part of a research program at McGill University, involving the testing of eight full-scale deep beams, this research studies the response of four full-scale deep beams that were designed in accordance with the strut-and-tie model provisions of the CSA Standard A23.3 (2004). All of the deep beams had a centre-to-centre spacing of 2000 mm between the two supports, 1000 mm in height, and 350 mm in thickness. They were simply supported with an application of a single point load at midspan. The total length of the four beams varies depending on the type of anchorage being used. The four anchorage details that were considered in this study include a straight development length, a standard 90 degree hook, friction-welded 1.5 in. (38 mm) diameter circular headed bars and friction-welded 2 in. (50 mm) diameter headed bars. The dimensions of the loading pad and the bearing pads were 200 mm (and 300 mm) and 100 mm, respectively. All beams were reinforced with two layers of five 15M bars forming the tension tie reinforcement. El-Jorf (2006) carried out the testing and analysis of the other four full-scale deep beams in this overall research program.This research project demonstrated that providing friction-welded circular headed bars capable of developing the full yield strength at the head results in shorter beams and improved response compared to straight bar embedment details. Providing a lead-in length as well as friction-welded circular headed bars, with reduced head size, provides improved ductility compared to the straight bar embedment and compared to the hooked anchorage. This research also shows that benefits of confinement pressures at the supports can increase the bar stress although the provided development length is below code requirements.
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Wong, Ha Hang Aaron. "Buckling and stability of slender reinforced concrete deep beams." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279763.
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Ashour, Ashraf Fawzy. "Behaviour and strength of reinforced concrete continuous deep beams." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319339.
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SANTOS, GLAUCIA GLEICE MACIEL DOS. "DESIGN METHODS FOR SIMPLY SUPPORTED REINFORCED CONCRETE DEEP BEAMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1262@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORAs principais recomendações para o dimensionamento de vigas-parede, como o ACI 318-95, o CEB-FIP, a Norma Canadense CAN-A23.3-M84 e o Guia 2 da CIRIA, apresentam métodos de cálculo que não cobrem satisfatoriamente o projeto de tais vigas. Outras normas, ainda, não trazem nenhuma indicação especial de dimensionamento. A própria Norma Brasileira, a NBR 6118, por exemplo, declara apenas que vigas desse tipo devem ser calculadas como chapas no regime elástico. O Código Britânico corrente BS 8110 explicitamente comenta que “para o projeto de vigas-parede, referência deve ser feita à literatura especializada”. Por razões como as citadas acima, a obtenção de um método racional, baseado em um claro mecanismo de ruptura e que leve em conta os principais parâmetros que influenciam a resistência última das vigas-parede tem sido o objetivo de vários pesquisadores de todo o mundo nas duas últimas décadas. Neste trabalho são apresentados, comentados e analisados vários métodos de dimensionamento de vigas-parede biapoiadas de concreto armado. Os métodos de cálculo são aplicados ao total de trinta e sete vigas ensaiadas no Laboratório de Estruturas e Materiais (L.E.M) da PUC-Rio, desde 1979, e a algumas vigas descritas na literatura, visando a obtenção de um método que gere resultados de carga última os mais próximos possíveis dos obtidos experimentalmente, e tendo como objetivo futuro a obtenção de recomendações que possam ser propostas para a Norma Brasileira.Os ensaios das trinta e sete vigas, no total, referenciadas acima, fazem parte de pesquisas teórico-experimentais realizadas na PUC-Rio por Guimarães (1980), Vasconcelos (1982) e Velasco (1984), sob a orientação do Prof. K. Ghavami. Várias conclusões foram obtidas em cada uma dessas dissertações de mestrado, separadamente, mas nenhum estudo havia sido feito no sentido de comparar os resultados encontrados. O presente trabalho também tem como objetivo obter informações comparativas relacionadas às 37 vigas citadas, com o respaldo da literatura atualizada.
The major codes that contain recommendations and discussions concerning the design of deep beams, including the ACI Building Code 318-95, the Canadian Code CAN-A23.3- M84, the CEB-FIP Model Code and the CIRIA Guide 2, present design methods that do not cover adequately the dimensioning of this type of beams. Nevertheless, some other codes don’t give any special recommendation. The Brazilian Code (NBR 6118), for instance, just explains that this type of beams should be calculated as a plate in elastic range. Another example is the current British Code BS 8110, which explicitly states that “for design of deep beams, reference should be made to specialist literature”. Because of reasons as those mentioned above, obtaining a rational method not only based on a clear mechanism of failure but taking into account the main parameters that have influence on the ultimate strength of deep beams, has been the purpose of several researchers in the whole world in the last two decades. In this work, some methods for the design of simply supported reinforced concrete deep beams are presented, examined and commented upon. These methods are applied to a total of 37 beams tested in the Laboratory of Structures and Materials (L.E.M) of PUC-Rio, since 1979, and to some beams reported in the literature, in order to yield a method which can predict results of ultimate load closer to those ones obtained experimentally. The future aim is to achieve recommendations that could be proposed to the Brazilian Code. The tests of the 37 beams just referred are included in theoretical-experimental research done by Guimarães (1980), Vasconcelos (1982) and Velasco (1984), which took place in PUC-Rio, orientated by Professor Khosrow Ghavami. Several concluding remarks were obtained in each Master Thesis, apart from one another, but there wasn’t any work that compared these results. The present work is also intended to provide some comparative information regarding the 37 deep beams mentioned above, with the support given by the current literature.
Las principales recomendaciones para el dimensionamiento de vigas- parede, como el ACI 318-95, el CEB-FIP, la Norma Canadiense CAN-A23.3-M84 y la Guía 2 de la CIRIA, presentan métodos de cálculo que no cubren satisfactoriamente el proyecto de tales vigas. Otras normas no ofrecen ninguna indicación especial de dimensionamiento. La própria Norma Brasileira, la NBR 6118, por ejemplo, declara solamente que vigas de ese tipo deben ser calculadas como chapas en el régimen elástico. El Código Británico actual BS 8110 explicitamente comenta que para
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Khatab, Mahmoud A. T. "Behaviour of continuously supported self-compacting concrete deep beams." Thesis, University of Bradford, 2016. http://hdl.handle.net/10454/14628.
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The present research is conducted to investigate the structural behaviour of continuously supported deep beams made with SCC. A series of tests on eight reinforced two-span continuous deep beams made with SCC was performed. The main parameters investigated were the shear span-to-depth ratio, the amount and configuration of web reinforcement and the main longitudinal reinforcement ratio. All beams failed due to a major diagonal crack formed between the applied mid-span load and the intermediate support separating the beam into two blocks: the first one rotated around the end support leaving the rest of the beam fixed on the other two supports. The amount and configuration of web reinforcement had a major effect in controlling the shear capacity of SCC continuous deep beams. The shear provisions of the ACI 318M-11 reasonably predicted the load capacity of SCC continuous deep beams. The strut-and-tie model recommended by different design codes showed conservative results for all SCC continuous deep beams. The ACI Building Code (ACI 318M-11) predictions were more accurate than those of the EC2 and Canadian Code (CSA23.3-04). The proposed effectiveness factor equations for the strut-and-tie model showed accurate predictions compared to the experimental results. The different equations of the effectiveness factor used in upper-bound analysis can reasonably be applied to the prediction of the load capacity of continuously supported SCC deep beams although they were proposed for normal concrete (NC). The proposed three dimensional FE model accurately predicted the failure modes, the load capacity and the load-deflection response of the beams tested.
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El-Jorf, Rula Refat. "Study of support bearing details on response of deep beams." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98956.
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This thesis reports on research, performed at McGill University, on the experimental responses of four deep beams forming part of a larger research program involving eight deep beams. The other four beams are reported by BouSaleh (2006).The beams reported in this thesis were tested in an attempt to obtain crushing at the support nodal zones through the provisions of inadequate bearing area for beams with different tension tie anchorage details.
In order to study the influence of different anchorages of the main tension tie, the beams were designed with the same strut-and-tie model in accordance with the CSA Standard (2004). The four full-scale simply supported deep beams had similar dimensions of 1000 mm in height, 350 mm in thickness, and a span of 2000 mm centre-to-centre between the supports. The four beams contained two layers of five 15M reinforcement. However, the length of each specimen varied according to the different anchorage details.
The tension tie reinforcement anchored by straight bar embedment resulted in the longest beam. Identical overall lengths were provided for the specimens anchored using 90° standard hooks and friction-welded headed bars of head size 1.5 in. (38 mm). Finally, the shortest beam was anchored using friction welded headed bars of 2 in. (50 mm) head size.
The beam containing hooked anchorages performed better than the beam with straight bar embedment, with higher capacity and ductility. The reduced head size friction-welded headed bars, further anchored with a lead-in length, resulted in a higher nodal zone bearing stresses, better confinement for the concrete and higher ductility compared to the straight bar embedment and the hooked anchorage. The friction-welded headed bars having heads with an area equal to ten times the bar area not only reduced the length of the beam significantly and were capable of developing the full yield strength of the bar at the inner side of the head. The beam with full size heads achieved a higher capacity than the beam with the straight bar embedment and reached about the same capacity as the beam with hooked end anchorage.
This research also demonstrates the beneficial effect of the confining transverse pressure provided at the support nodal zones by the support reactions, in improving the bond. This effect resulted in higher bar stresses than those predicted using the CSA and ACI code development length expressions.
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Shalookh, Othman H. Zinkaah. "Behaviour of continuous concrete deep beams reinforced with GFRP bars." Thesis, University of Bradford, 2019. http://hdl.handle.net/10454/18381.
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Kulkarni, Allakh. "An Application of Strut-and-Tie Model to Deep Beams." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1312554372.
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Wong, Kam Kau. "Shear strength and bearing capacity of reinforced concrete deep beams." Thesis, University of Leeds, 1986. http://etheses.whiterose.ac.uk/450/.
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Reinforced concrete deep beans with small span/depth ratios usually fail by crushing of concrete in the bearing zone above the supports. In order to increase the load carrying capacity of deep beans, bearing strength around the supports should be enhanced. The first part of this study involved the investigation of bearing capacity of plain and reinforced concrete blocks. Effects of edge distance, footing to loading area ratios, heights, base friction and size effect are studied with plain concrete blocks. Bearing capacities of reinforced concrete blocks with different forms, diameter and spacing of reinforcement are also investigated. It is found that interlocking stirrups at small spacing are the most effective form of reinforcement. A failure mechanism for a concrete block in bearing is proposed and found to give the best estimate as compared with other models by different researchers. The second part is concerned with the behaviour of reinforced concrete deep beans with span/depth ratios ranging from 0.7 to 1. 1. These beans were tested under uniformly distributed load at the top. It is found that a shear crack is formed along the line joining the inner edge of the support to the third point at the top level of the bean. The concrete block on the outer side of the crack rotates about the centre of pressure in the compression zone. Shear strength is determined by shear in the compression zone, aggregate interlock of the shear crack and dowel action and the components of forces of reinforcement across the crack. Based on these observations, a model of the failure mechanism in shear is proposed which gives excellent results in comparison with other models proposed.
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Cheng, Bei, and 程蓓. "Retrofitting of deep concrete coupling beams by laterally restrained side plates." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B45791132.
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Kunieda, Minoru, Naoshi Ueda, Yoshihito Yamamoto, Hikaru Nakamura, and Yasar Hanifi Gedik. "Effect of Stirrups on the Shear Failure Mechanism of Deep Beams." 日本コンクリート工学会, 2012. http://hdl.handle.net/2237/20960.
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Bechtel, Andrew Joseph. "External strengthening of reinforced concrete pier caps." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42809.
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The shear capacity of reinforced concrete pier caps in existing bridge support systems can be a factor which limits the capacity of an existing bridge. In their usual configuration, pier caps behave as deep beams and have the ability to carry load through tied arch action after the formation of diagonal cracks. Externally bonded fiber reinforced polymer (FRP) reinforcement has been shown to increase the shear capacity of reinforced concrete members which carry load through beam action. However, there is an insufficient amount of research to make it a viable strengthening system for beams which carry load through arch action, such as pier caps. Accordingly, this research was aimed at investigating the behavior of reinforced concrete pier caps through a coordinated experimental and analytical program and to recommend an external strengthening method for pier caps with perceived deficiencies in shear strength.
The experimental study was performed on laboratory specimens based on an existing bridge in Georgia. A number of factors were examined, including size, percentage longitudinal reinforcement and crack control reinforcement. The results showed that increasing the longitudinal tension reinforcement increased the beam capacity by changing the shape of the tied arch. In contrast, the presence of crack control reinforcement did not change the point at which diagonal cracking occurred, but it did increase the ultimate capacity by reinforcing the concrete against splitting. The results of the experimental study were used in conjunction with a larger database to examine different analytical methods for estimating the ultimate capacity of deep beams, and a new method was developed for the design of external strengthening. Two specimens were tested with externally bonded FRP reinforcement applied longitudinally to increase the strength of the tension tie. The test results correlated well with the proposed method of analysis and showed that increasing the strength of the longitudinal tension tie is an effective way to increase the strength of a reinforced concrete deep beam.
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張敬東 and Jingdong Zhang. "The development of positron deep level transient spectroscopy using variable energy positron beam and conventional deep level transientspectroscopy using digital capacitance meter." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31227077.
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Zhang, Jingdong. "The development of positron deep level transient spectroscopy using variable energy positron beam and conventional deep level transient spectroscopy using digital capacitance meter /." Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25155076.
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Shahnewaz, Md. "Shear behavior of reinforced concrete deep beams under static and dynamic loads." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44521.
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Reinforced concrete (RC) deep beams predominantly fail in shear which is brittle and sudden in nature that can lead to catastrophic consequences. Therefore, it is critical to determine the shear behavior of RC deep beams accurately under both static and dynamic loads.
In this study, a database of the existing experimental results of deep beams failing in shear under static loading was constructed. The database was used to propose two simplified shear equations using genetic algorithm (GA) to evaluate the shear strength of deep beams with and without web reinforcement under static loads. Reliability analysis was performed to calibrate the equations for design purposes. The resistance factors for the design equations were calculated for a target reliability index of 3.5 to achieve an acceptable level of structural safety.
A deep beam section designed following the building codes considering only static loads may behave differently under dynamic loading condition. Therefore, in this study, deep beams were analyzed under reversed cyclic loading to simulate the seismic effects. The ultimate load capacity, energy dissipation capacity, and ductility capacity were calculated in deep beams with different reinforcement ratios.
In RC structures, deep beams have interaction with other structural elements through connections. Therefore, to predict the shear behavior of deep beams in real structure under seismic loads, it is necessary to analyze a full structure with a deep beam. A seven storey RC office building with a deep transfer beam was designed following the CSA A23.3 standards. The structure was analyzed using non-linear pushover and non-linear dynamic time history analysis. The deep beam was evaluated for the shear deficiency under different earthquake records for the soil condition of the City of Vancouver. The analysis results showed a significant shear deficiency of about 25% in the deep beam. The use of carbon fibre reinforced polymer (CFRP) resulted in increasing the shear capacity of a deep beam by up to 82%.
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Hosseini, Rahimeh, and Anita Nolsjö. "The effect of reinforcement configuration on crack widths in concrete deep beams." Thesis, KTH, Betongbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208709.
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Reinforced concrete deep beams are known for applications in tall buildings, foundations and offshore structures. Deep beams are structural elements with length and height within the same magnitude and have significantly smaller thickness compared to a conventional concrete beam. Deep beams in bending have non-linear strain distribution compared to conventional beams where Bernoulli’s hypothesis is valid. Crack formation is a common problem in reinforced concrete structures, which reduce the durability of the structure. Once the concrete cracks the tension reinforcement carry the tensile forces instead of the concrete. Therefore, the design of tension reinforcement is important since the serviceability should be retained even after the structure cracks. The crack widths can be limited by using proper reinforcement and one alternative is to combine tensile reinforcement with crack reinforcement. The function of the reinforcement is to distribute the cracks over the cross section which leads to that many smaller cracks occur instead of fewer, wider cracks. Small cracks are seen as less of a problem compared to large cracks since larger cracks reduce the durability significantly. For deep beams, there is at the present no well-substantiated analysis model for how crack widths shall be calculated when having reinforcement in multiple layers with different diameters. The use of crack reinforcement in the outer bottom layer has by tradition been considered as a cost efficient way to achieve small crack widths. In this work the crack width in deep beams have been analysed using the finite element program Atena 2D. The numerical results have been verified by analytical calculations based on Eurocode 2. The aim is to achieve reduced crack widths by analysing the combination of crack- and tensile reinforcement compared to the case with tensile reinforcement only. Tensile reinforcement has a larger diameter, for example ø25 mm, and crack reinforcement has smaller diameters, often between ø10 and ø16 mm. The result from the calculations with Atena showed that there was an improvement regarding the reduction of crack widths when using crack reinforcement in combination with tensile reinforcement compared to using tensile reinforcement only. However, this improvement decreased by using reinforcement in multiple layers since a tensile reinforcement bar 1ø25 mm needed to be replaced by approximately six crack reinforcement bars 6ø10 mm in order to achieve the same total reinforcement area. The main disadvantage was that more space was required to place all reinforcement bars in the cross section, which reduced the lever arm. The reduction of the lever arm resulted in a reduced capacity for the reinforcement and the cracks might unintentionally become wider than expected. Furthermore, significant reduction of both crack widths and reinforcement stresses were obtained when the total area for a case with 7ø25 mm was increased to 9ø25 mm. The increased total area of only tensile reinforcement ø25 mm reduced the crack width more compared to using a combination of crack- and tensile reinforcement, which could simplify the construction work at building sites and minimize time consumption.Armerade höga betongbalkar är kända för tillämpningar i höga byggnader, grundsulor och offshore konstruktioner. Höga balkar är konstruktionselement med längd och höjd i samma storleksordning och har betydligt mindre tjocklek jämfört med en konventionell betongbalk. Höga balkar i böjning har en icke-linjär töjningsfördelning jämfört med konventionella balkar där Bernoullis hypotes gäller. Sprickbildning är ett vanligt problem i armerade betongkonstruktioner, vilket minskar beständigheten hos konstruktionen. När betongbalken spricker kommer armeringen att ta upp dragkraften istället för betongen därför är utformningen av böjarmering viktig eftersom bruksgränstillståndet bör behållas även efter att konstruktionen spricker. Sprickvidderna kan begränsas genom att använda korrekt armering och ett alternativ är att kombinera kraftarmering med sprickarmering. Armeringens funktion är att sprida ut sprickorna över tvärsnittet vilket leder till att många små sprickor uppkommer i stället för färre, bredare sprickor. Små sprickor ses som ett mindre problem jämfört med stora sprickor eftersom större sprickor minskar beständigheten avsevärt. För höga balkar finns det för närvarande ingen välunderbyggd analysmodell för hur sprickvidder ska beräknas när de har armering i flera lager och med olika diametrar. Användningen av sprickarmering har traditionellt ansetts vara ett kostnadseffektivt sätt att uppnå små sprickvidder. I detta arbete har sprickvidden i höga balkar analyserats med hjälp av finita elementprogrammet Atena 2D. De numeriska resultaten har verifierats med analytiska beräkningar baserade på Eurokod 2. Syftet är att uppnå reducerade sprickvidder genom att analysera kombinationen av sprick- och kraftarmering jämfört med fallet med endast kraftarmering. Kraftarmeringen har en större diameter, till exempel ø25 mm och sprickarmering har mindre diametrar, ofta mellan ø10 och ø16 mm. Resultaten från beräkningarna i Atena visade att sprickvidderna minskade vid användning av sprickarmering i kombination med kraftarmering jämfört med användning av endast kraftarmering. Denna förbättring minskade emellertid i och med användning av armering i flera lager. En kraftarmeringsstång 1ø25 mm behöver ersättas med ungefär sex sprickarmeringsstänger, 6ø10 mm, för att uppnå samma totala armeringsarea. Den största nackdelen var att det krävdes mer utrymme för att placera alla sprickarmeringsstänger i tvärsnittet, vilket minskade hävarmen. Minskningen av hävarmen medförde en reducerad kapacitet i armeringen och sprickorna blev bredare än förväntat. Vidare erhölls signifikant reduktion av både sprickvidder och armeringsspänningar när den totala arean för ett fall med 7ø25 mm ökades till 9ø25 mm. Den ökade totalarean av endast kraftarmeringsstänger ø25 mm minskade sprickvidden mer jämfört med att använda en kombination av sprick- och kraftarmering vilket skulle kunna förenkla byggarbetet på byggarbetsplatser och minimera tidsförbrukningen.
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Li, Ding 1969. "Behaviour and modeling of deep beams with high shear span-to-depth ratios." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80119.
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A study of the response of eight full-scale deep beams was carried out at McGill University. Four beams were tested by Li (2003) and this thesis reports on the testing of the remaining four beams. The deep beams reported in this thesis were 2000 mm long by 400 mm thick. Two beams had an overall depth of 520 mm and the other two beams had an overall depth of 810 mm. Two beams were reinforced with main tension tie reinforcement only, while the other two contained both vertical and horizontal uniformly distributed reinforcement.These beams were tested under concentrated load to investigate the influence of span-to-depth ratio and the influence of uniformly distributed horizontal and vertical reinforcement. The presence of uniformly distributed steel resulted in higher capacities, better crack control and also served to control bond splitting failures near the supports. Four approaches were used to predict the capacities: a plane-section model, a simplified strut-and-tie model, a model based on the 1996 FIP Recommendations and a refined strut-and-tie model. The 1996 FIP (Federation Internationale de la Precontrainte) Recommendations gave conservative predictions suitable for design. The refined strut-and-tie model gave the most accurate predictions due to the fact that this approach accounted for the contributions of both the horizontal and vertical uniformly distributed reinforcement in the strut-and-tie model.
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Li, Zhen Yu 1972. "Behaviour and modeling of deep beams with low shear span-to-depth ratios." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80122.
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The purpose of this research program was to study the behaviour of full-scale deep beams with realistic reinforcement details. In the overall research program, a total of eight deep beams were tested. A companion study by Li (2003) presents the results of four of these beams. This research examines the other four beams, two without uniformly distributed crack control reinforcement and two with distributed horizontal and vertical reinforcement. The specimens' dimensions were 2000 mm long and 400 mm thick, with two specimens having heights of 1160 mm and the other two heights of 1840 mm. The specimens were loaded with a central loading plate 300 mm long and 400 mm wide. The end bearing plates were 250 mm long and 400 mm wide. All specimens contained seven 15M bars forming the main tension tie reinforcement.The test results provided information on the influence of the uniformly distributed reinforcement and the crack and strain development up to failure. The ductility of the specimens containing only the main tension ties was limited due to the formation of splitting cracks along the anchorages of the main tension ties during the later stages of testing. The uniformly distributed reinforcement provided additional tension ties that increased the capacity and the ductility. Strut-and-tie models were developed to predict the capacities. The FIP Recommendations (FIP 1996) were used to determine the contributions of the two major mechanisms, direct strut action and indirect strut action. This approach gave very conservative strength predictions. More refined strut-and-tie models were developed for the specimens with uniformly distributed reinforcement. These refined models gave more accurate predictions of the capacities of the deep beams.
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Albarram, Ahmed. "Behaviour of headed stud connectors in composite beams with very deep profiled sheeting." Thesis, University of East London, 2018. http://roar.uel.ac.uk/8079/.
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Lack of design rules and no past research on the behaviour of composite beams with steel decks deeper than 80 mm is a major knowledge gap. Thus, this research provides fundamental information on the behaviour of headed stud connectors with narrow and very deep decks. After a series of extensive validation, a vast number of 3-D push-off tests are modelled using ABAQUS/Explicit package. Both secondary and primary composite beam systems are investigated. Critical examination is conducted on the existing design equations to assess their accuracy in predicting the shear stud capacity with the use of narrow and very deep decks. The numerical analysis regarding the secondary composite beams showed that the shear stud capacity with narrow and very deep decks (i.e. 100 and 146 mm deep) was almost 65% of that obtained from the traditional steel decks (60-80 mm deep). The shear stud capacity was mainly affected by the concrete embedded within ribs. Reinforcing that area by a unique wire-mesh bars layout, which has not been investigated before, led the load bearing capacity to increase by 24%. For the primary composite beams, the numerical analysis indicated that the correlation between very deep decks and traditional ones regarding the shear stud capacity can not be represented through the rib deck geometry as it was believed in the past. A new concept was introduced to more accurately explain that correlation. This was through the effective cross-sectional area of concrete. The existing design equations, when validated, did not account for narrow and very deep decks. As a result, a big discrepancy up to 50% was noticed between the predicted strengths and FE results in some cases, especially among EC4 and ANSI/AISC provisions. This necessitated to introduce more effective formulae. The developed equations regarding the secondary composite beams covered for the first time a wide range of ribbed geometries including narrow and very deep decks. For the primary composite beams, the correlation between different types of decks was established in the new equations through the effective cross-sectional area of concrete. The reliability of the new equations was proven against many previous experiments. The accuracy in results remained within ±10%. Besides the accuracy, the new equations are easy to use. This will help the designers to directly apply these equations in the practice.
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Mohamed, Khaled Ahmed. "Performance and strut efficiency factor of concrete deep beams reinforced with GFRP bars." Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/7613.
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Abstract : Deep reinforced concrete beams are commonly used as transfer girders or bridge bents, at which its safety is often crucial for the stability of the whole structure. Such elements are exposed to the aggressive environment in northern climates causing steel-corrosion problems due to the excessive use of de-icing salts. Fiber-reinforced polymers (FRP) emerged as non-corroded reinforcing materials to overcome such problems in RC elements. The present study aims to address the applicability of concrete deep beams totally reinforced with FRP bars. Ten full-scale deep beams with dimensions of 1200 × 300 × 5000 mm were constructed and tested to failure under two-point loading. Test variables were shear-span depth ratio (equal to 1.47, 1.13, and 0.83) and different configurations of web reinforcement (including vertical and/or horizontal web reinforcement). Failure of all specimens was preceded by crushing in the concrete diagonal strut, which is the typical failure of deep beams. The test results indicated that, all web reinforcement configurations employed in the tested specimens yielded insignificant effects on the ultimate strength. However, strength of specimens containing horizontal-only web reinforcement were unexpectedly lower than that of specimens without web reinforcement. The web reinforcement’s main contribution was significant crack-width control. The tested specimens exhibited reasonable deflection levels compared to the available steel-reinforced deep beams in the literature. The development of arch action was confirmed through the nearly uniform strain distribution along the length of the longitudinal reinforcement in all specimens. Additionally, the basic assumption of the strut-and-tie model (STM) was adequately used to predict the strain distribution along the longitudinal reinforcement, confirming the applicability of the STM for FRP-reinforced deep beams. Hence, a STM based model was proposed to predict the strength of FRP-reinforced deep beams using the experimental data, in addition to the available experimentally tested FRP-reinforced deep beams in the literature. Assessment of the available STMs in code provisions was conducted identifying the important parameters affecting the strut efficiency factor. The tendency of each parameter (concrete compressive strength, shear span-depth ratio, and strain in longitudinal reinforcement) was individually evaluated against the efficiency factor. Strain energy based calculations were performed to identify the appropriate truss model for detailing FRP-reinforced deep beams, hence, only four specimens with vertical web reinforcement exhibited the formation of two-panel truss model. The proposed model was capable to predict the ultimate capacity of the tested deep beams. The model was also verified against a compilation of a data-base of 172 steel-reinforced deep beams resulting in acceptable level of adequacy. The ultimate capacity and performance of the tested deep beams were also adequately predicted employing a 2D finite element program (VecTor2), which provide a powerful tool to predict the behavior of FRP-reinforced deep beams. The nonlinear finite element analysis was used to confirm some hypotheses associated with the experimental investigations.Résumé : Les poutres profondes en béton armé (BA) sont couramment utilisées comme poutre de transfert ou coude de pont, comme quoi sa sécurité est souvent cruciale pour la sécurité de l’ensemble de la structure. Ces éléments sont exposés à un environnement agressif dans les climats nordiques causant des problèmes de corrosion de l’acier en raison de l’utilisation excessive de sels de déglaçage. Les polymères renforcés de fibres (PRF) sont apparus comme des matériaux de renforcement non corrodant pour surmonter ces problèmes dans les BA. La présente étude vise à examiner la question de l'applicabilité des poutres profondes en béton complètement renforcées de barres en PRF. Dix poutres profondes à grande échelle avec des dimensions de 1200 × 300 × 5000 mm ont été construites et testées jusqu’à la rupture sous chargement en deux points. Les variables testées comprenaient différents ratios de cisaillement porté/profondeur (égal à 1.47, 1.13 et 0.83) ainsi que différentes configurations d’armature dans l’âme (incluant un renforcement vertical avec ou sans renforcement horizontal). La rupture de tous les spécimens a été précédée par l’écrasement du béton dans le mât diagonal, ce qui est la rupture typique pour les poutres profondes en BA. Les résultats ont révélé que toutes les configurations de renforcement de l’âme employées dans les spécimens d'essais avaient un effet négligeable sur la résistance ultime. Toutefois, la résistance des spécimens contenant uniquement un renforcement horizontal était étonnamment inférieure à celle des spécimens sans renforcement. La contribution principale du renforcement de l’âme était dans le contrôle de la largeur de fissuration. Les spécimens examinés présentaient une déflexion raisonnable par rapport à ce qui est disponible pour les poutres profondes renforcées en acier dans la littérature. Le développement de l'effet d'arche a été confirmé par la distribution quasi uniforme des déformations le long du renforcement longitudinal dans tous les spécimens. En outre, l'hypothèse de base du modèle des bielles et tirants (MBT) a été utilisée adéquatement pour prédire la distribution de déformation le long du renforcement longitudinal, confirmant l'applicabilité du MBT pour les poutres profondes armées de PRF. Par conséquent, un modèle basé sur un MBT a été proposé afin de prédire la résistance des poutres profondes renforcées de PRF en utilisant les données expérimentales en plus de la mise à l'épreuve expérimentalement des poutres profondes renforcées de PRF trouvées dans la littérature. Une évaluation des MTB disponibles dans les dispositions des codes a été menée afin de déterminer les paramètres importants affectant le facteur d'efficacité de la bielle. La tendance de chaque paramètre (la résistance à la compression du béton, le ratio de cisaillement porté/profondeur, et la déformation dans le renforcement longitudinal) a été évaluée individuellement contre le facteur d'efficacité. Des calculs basés sur l’énergie des déformations ont été effectués pour identifier le modèle de treillis approprié afin de détailler les poutres profondes renforcées de PRF. Par conséquent, seulement quatre spécimens avec un renforcement vertical dans l’âme présentaient la formation de modèles avec deux panneaux de treillis. Le modèle proposé a été capable de prédire la capacité ultime des poutres profondes testées. Le modèle a également été vérifié contre une base de données de 172 poutres profondes renforcées en acier aboutissant en un niveau acceptable de pertinence. La capacité ultime et la performance des poutres profondes testées ont été également adéquatement prédites employant un programme d'éléments finis en 2D (VecTor2), ce qui fournira un puissant outil pour prédire le comportement des poutres profondes renforcées de PRF. L'analyse non linéaire par éléments finis a été utilisée afin de confirmer certaines hypothèses associées à l'étude expérimentale.
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Gong, Min, and 龔敏. "A study of implantation and irradiation induced deep-level defects in 6H-SiC." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B3123849X.
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Gong, Min. "A study of implantation and irradiation induced deep-level defects in 6H-SiC /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20567078.
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Scott, Jonathan Paul. "First direct measurement of Fâ†L using ISR events in deep inelastic scattering at HERA." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326678.
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Shaker, I. M. "The strength and behaviour of fibre reinforced concrete deep beams with and without web openings." Thesis, Cardiff University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377128.
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Oliver, Katie Rosemarie. "Measurement of high Q² charged-current deep inelastic scattering with polarised positron beams using the ZEUS detector at HERA." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589602.
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This thesis presents measurements of charged current deep inelastic scattering cross sections in e+p collisions with longitudinally polarised positron beams. The measurements are based on data taken by the ZEUS detector at the HERA collider during the 2006-2007 run- ning period. The data sample has an integrated luminosity of 132 pb-1 and was taken at a centre-of-mass energy of 318 GeY. The total cross section has been measured at positive and negative values of the longitu- dinal polarisation of the positron beam (Pe). In addition, the single differential cross sections dδ / dQ2, dδ / dx and dδ / dy have been measured for Q2 > 200 Ge y2, also using both positively and negatively polarised positron beams. The reduced cross section has been measured in nine bins of Q2 in the kinematic range 280 < Q2 < 30000 Gey2 and 0.0078 < x < 0.42. The results are compared against the descriptions provided by the CTEQ6.6, MSTW 2008, HEARPDF1.0 and ZEUS-JETS PDFs. In general, the measured cross sections are well described by these predictions. Based on the measurement of the total cross section as a function of the polarisation of the positron beam, a lower limit on the mass of a hypothetical right-handed W boson has been extracted from the upper limit of the cross-section at Pe = -1. This limit is complementary to the limits obtained from direct searches (for example at CDF and D0) because the limit presented herein is for a space-like vV, whereas for direct searches, the limit on the mass of a time-like W boson is obtained. The results of this analysis have been published and have been included ill the determination of the HERAPDF theoretical prediction and also in HI and ZEUS combined results.
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Di, Tommaso Nicholas. "Influence of concrete strength and uniformly distributed reinforcement ratio on the behaviour of concrete deep beams." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114386.
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Six full-scale reinforced concrete deep beams were constructed and tested to investigate the influence of concrete strength on their behaviour. Two levels of uniformly distributed reinforcement steel were tested for three pairs of deep beams with different concrete strengths to determine the influence of the reinforcement ratio on performance. Simple strut-and-tie models, refined strut-and-tie models, and sectional analysis are used to predict the behaviour of the specimens and to verify design approaches. It was found that increased concrete strength resulted in an increase in the ratio of the bearing stress at crushing to the compressive strength of the concrete. An increase in the reinforcement ratio from 0.2% to 0.3% resulted in smaller crack widths at service load level.Six poutres profondes de grandeur réelle en béton armé ont été construits et testés pour étudier l'influence de la résistance du béton sur leur comportement. Deux niveaux d'armature distribuée uniformément ont été testés pour trois paires de poutres profondes avec des bétons de différentes résistances pour étudier l'influence du ratio d'armature sur la performance. Des modèles de bielle et tirant simples, des modèles de bielle et tirants plus complexes, et l'analyse par section sont utilisés pour prédire le comportement des spécimens et pour vérifier les approches de conception. Une augmentation de la résistance du béton a entraîné une augmentation du ratio de la contrainte d'écrasement à la résistance du béton en compression. Une augmentation du ratio d'armature de 0.2% à 0.3% a entraîné une diminution de la largeur des fissures à la charge de service.
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Bahen, Neil P. "Strut-and-tie modeling for disturbed regions in structural concrete members with emphasis on deep beams." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1447626.
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Brindley, Monika. "Shear assessment and strengthening of reinforced concrete T-beams with externally bonded CFRP sheets." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.761006.
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Existing reinforced concrete bridges may be deemed inadequate to carry the ever-increasing traffic loads according to the current codes and standards before they reach the end of their design life. It may therefore be required to either strengthen or replace these structures, which can be costly and causes disruptions to the infrastructure. This work investigates experimentally the possibilities to extend the useful life of existing reinforced concrete slab-on-beam structures deficient in shear by means of structural strengthening with fibre-reinforced polymers (FRP). The experimental campaign involved mechanical testing of ten full-scale T-beam specimens, representative of typical existing slab-on-beam bridges. Two sizes of test specimen were used to investigate the effect of size on the ultimate shear capacity of the beams. The investigated shear-strengthening configurations included externally bonded carbon fibre reinforced polymer (CFRP) sheets in a U-wrap configuration with and without end-anchorage and deep embedded CFRP bars. Unstrengthened control specimens were also tested to provide baseline for comparison. The results from the experimental programme revealed that while the deep embedment strengthening solution provides an increase in shear capacity of up to 50%, the strengthening with CFRP U-wraps results in reduced capacity compared with the underlying control beam. This presents a major implication in terms of safe design predictions of shear capacity of reinforced concrete T-beams strengthened with CFRP sheets as this is the most commonly used shear-strengthening scheme in practice. The study also demonstrated that greater contribution from the externally bonded CFRP U-wraps can be achieved using end-anchorage systems, which delay the debonding of the CFRP. The applicability of current codes of standards and guidelines was studied as well as appropriateness of using advanced numerical methods for assessment of existing reinforced concrete structures. It was found that while the standards used for assessment greatly under-predict the shear capacity, the guidelines for FRP-strengthened beams either under- or over-predict the shear capacity of the tested beams. More accurate predictions are possible using advanced fracture mechanics-based methods for both the unstrengthened as well as the strengthened beams.
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Ruske, Olaf Christian. "Measurement and phenomenology of the proton structure function Fâ†2 using the 1996 and 1997 ZEUS data at HERA." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365789.
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Ekesiöö, Anton, and Andreas Ekhamre. "Safety formats for non-linear finite element analyses of reinforced concrete beams loaded to shear failure." Thesis, KTH, Betongbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231087.
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There exists several different methods that can be used to implement a level of safety when performing non-linear finite element analysis of a structure. These methods are called safety formats and they estimate safety by different means and formulas which are partly discussed further in this thesis. The aim of this master thesis is to evaluate a model uncertainty factor for one safety format method called the estimation of coefficient of variation method (ECOV) since it is suggested to be included in the next version of Eurocode. The ECOV method will also be compared with the most common and widely used safety format which is the partial factor method (PF). The first part of this thesis presents the different safety formats more thoroughly followed by a theoretical part. The theory part aims to provide a deeper knowledge for the finite element method and non-linear finite element analysis together with some beam theory that explains shear mechanism in different beam types. The study was conducted on six beams in total, three deep beams and three slender beams. The deep beams were previously tested in the 1970s and the slender beams were previously tested in the 1990s, both test series were performed in a laboratory. All beams failed due to shear in the experimental tests. A detailed description of the beams are presented in the thesis. The simulations of the beams were all performed in the FEM- programme ATENA 2D to obtain high resemblance to the experimental test. In the results from the simulations it could be observed that the ECOV method generally got a higher capacity than the PF method. For the slender beams both methods received rather high design capacities with a mean of about 82% of the experimental capacity. For the deep beams both method reached low design capacities with a mean of around 46% of the experimental capacity. The results regarding the model uncertainty factor showed that the mean value for slender beams should be around 1.06 and for deep beams it should be around 1.25.
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O'Malley, Curtis John. "Experimental testing, analysis, and strengthening of reinforced concrete pier caps by exterior post tensioning." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41076.
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Condition assessment of existing concrete bridge pier caps using the general shear provisions of the AASHTO LRFD Bridge Design Specification has caused the Georgia Department of Transportation (GDOT) to post a large number of bridges in the State of Georgia. Posting of bridges disrupts the free flow of goods within the region served by the bridge and has a negative economic impact. To prevent structural deterioration, diagonal cracking or failure of concrete pier caps in shear, the GDOT employs an in-situ strengthening technique that utilizes an external vertical post-tensioning system. However, the fundamental mechanics of this system and its effectiveness under service load have not been examined previously.
This research examines the behavior of reinforced concrete pier caps that utilize the above strengthening system in a combined analytical and experimental program. In the experimental part of the study, two groups of full-scale reinforced concrete deep beam specimens were tested. The first group consisted of six deep beams with shear span/depth ratios of approximately 1.0, which is typical of bridge pier caps; of these six, two included the external post-tensioning system. In the second group, nine deep beam specimens that included a segment of the column representing the pier were tested; four of those tests included the external post-tensioning system. The tests revealed that the shear capacity computed using the AASHTO LRFD Bridge Design Specifications provided a conservative estimate of the specimen capacity in all but one case when compared to the experimental results. However, the AASHTO strut and tie provisions were found to provide a much closer assessment of the load carrying mechanism in the pier cap than the general shear provisions, in that they were able to predict the load at which yielding of the tension reinforcement occurred as well as the angle of the compression strut. The presence of the column segment in the second group had a significant impact on the failure mechanism developed in the specimen near ultimate load. The stress concentration at the reentrant corner between the pier cap and column interface served as an attractor for the formation of diagonal shear cracks, a mechanism not observed in previous deep beam tests in shear. The research has led to recommendations for improving the design of pier caps and the external post-tensioning system, where required, based on mechanics which are consistent with the results of the experimental program.
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Rezaei, Nazanin. "Study on Strut and Node Behavior in Strut-and-Tie Modeling." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3749.
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The strut-and-tie method (STM) is a simple and conservative method for designing concrete structures, especially deep beams. This method expresses complicated stress patterns as a simple truss or kinematic model made up of compression elements (struts), tension elements (ties), and the joints between elements (nodes). STM is based on lowerbound plasticity theorem, so using it properly will lead to a conservative design. Although the concepts of STM have been around in concrete design since the late 19th century, STM was first introduced in AASHTO LRFD in 1994 and ACI 318-02 in 2002. ACI 318 defines two different types of struts (prismatic and bottle-shaped) based on whether compression stress can spread transversely along the length of the strut. Recent work has brought into question whether these two types of struts do exist and whether current design provisions conservatively estimate failure loads for all members. The performance of struts and nodes were investigated experimentally by testing six fullscale concrete deep beams. The specimens had two different shapes (rectangular and trusslike), two different shear span-to-depth ratio (1 and 1.6), and three different types of development (externally unbonded bars, internally bonded hooked bars, and internally bonded bars with welded external plates). All the specimens were supported vertically and vii tested under a three-point load setup. Based on the results, the truss-like specimen failed at higher loads than rectangular specimens with the same shear span-to-depth ratio. According to these results and recent debate in the literature, bottle-shaped struts are not weaker than prismatic struts because of their shape. They are weaker due to shear failure where struts cross a diagonal tension field. Therefore, the structures should be separately checked for shear strength when they are designed with STM. In this dissertation, the development of the design equation for shear strength of discontinuity regions was introduced, and the procedure is under consideration for adoption in ACI 318-19. This research was expanded numerically by studying the effect of development type and length, strut type, and strut angle on the behavior of concrete deep beams. The crack patterns and load-displacement curves, which were obtained from experimental tests, were used to validate numerical models. The strength of concrete deep beams was assessed by modeling thirty-five specimens in a nonlinear finite element software. According to the results, development length and development types influenced the presence of tensile stress in the support nodes. Additionally, the effect of the tensile stresses from reinforcement development and diagonal tension were not additive in rectangular specimens.
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Bondsman, Benjamin, Barzan Al, and Felix Hedlund. "Dimensionering av höga balkar enligt fackverksanalogi : -En parametrisk studie." Thesis, Högskolan i Gävle, Energisystem och byggnadsteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-29936.
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Karlsson, Evelina. "Dimensionering av höga balkar av armerad betong : En jämförelse mellan EK2, BBK, laboratorieförsök och ATENA 2D." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-81429.
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Detta examensarbete vid Luleå tekniska universitet har utförts i samarbete med avdelningen för byggkonstruktionvid det nordiska konsultföretaget Norconsult AB. Arbetet bygger på en önskan från Norconsultatt ta fram en beräkningsmodell för höga balkar i överensstämmelse med Eurokod 2 motsvarande densom finns i BBK 04. Eurokod 2 har endast en knapphändig beskrivning av hur höga balkar bör dimensioneras.Detta skapar frustration och osäkerhet hos konstruktörer. Den tidigare svenska betongnormen,BBK 04, innehöll en tydlig och enkel mer empirisk beräkningsmetod för höga balkar, vilket gav en störresäkerhet vid projekteringen. Arbetet begränsas till att studera enkelt upplagda och kontinuerliga balkar i två spann belastade med enpunktlast mitt i vartdera spannet. Geometrin är densamma för samtliga balkar och armeringsmängdenvarieras tillsammans med brottlasten. Initialt utfördes en litteraturstudie för att erhålla en fördjupad kunskap om området samt att bygga uppen förståelse för teorin för höga balkar och den fackverksmodell som används i Eurokod 2. Vidare presenterasen försöksrapport, Rogowsky et al. (1983), som redovisar en experimentell laboratoriestudie därhöga balkar belastas till brott. Resultaten som presenteras är brottlast, töjning i betong och armering,sprickmönster samt nedböjning. Fyra enkelt upplagda och fyra kontinuerliga balkar väljs ut för vidarejämförelse och analys. Härvid används det ickelinjära beräkningsprogrammet ATENA 2D, där studeradebalkar modelleras. Handberäkningar enligt EK2 och BBK 04 utförs för respektive balk och tillhörandearmeringsmängd beräknas. En maximal brottlast itereras fram för respektive balk och beräkningsmetod (EK2 eller BBK 04). Armeringsmängdensom ges av denna beräkning modelleras i ATENA 2D och motsvarande balk analyseras.Resultaten jämförs sedan. Erhållna resultat sammanställs och jämförs med varandra: Rogowsky et al. (1983), ATENA 2D och handberäkningarnaenligt både Eurokod 2 och BBK 04. Jämförelsen visar att det finns få likheter mellan EK2och BKK 04, med avseende på erhållen armeringsmängd. BBK kräver generellt större armeringsmängdän Eurokod 2. Studien visar att beräkningarna med ATENA 2D stämmer väl överens med laboratorieförsöken.Resultaten visar även att antaganden enligt Eurokod 2 stämmer väl överens med hur de studeradebalkarna beter sig i verkligheten. En enkel beräkningsmodell som motsvarar BBKs konservativa modell är inte möjlig att ta fram inom deramar och begränsningar som finns för detta examensarbete. Istället sammanställs en modell i form av enpunktlista som förtydligar, sammanfattar och exemplifierar den mer verklighetstrogna beräkningsgångenför höga balkar enligt Eurokod 2.
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KUNIEDA, Minoru, Yoshihito YAMAMOTO, Hikaru NAKAMURA, and Y. Hanifi GEDIK. "3D-RBSM ANALYSIS OF DEEP BEAM FAILED IN SHEAR." 日本コンクリート工学会, 2010. http://hdl.handle.net/2237/20928.
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Andermatt, Matthias. "Concrete deep beams reinforced with internal FRP." Master's thesis, 2010. http://hdl.handle.net/10048/1518.
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Concrete deep beams with small shear span-to-depth (a/d) ratios are common elements in structures. However, there are few experimental results on the behaviour of FRP reinforced concrete deep beams and no specific modelling techniques exist in design codes for such members. The objectives of this study were to examine the shear behaviour of FRP reinforced concrete deep beams containing no web reinforcement and to develop a modelling technique.
Test results of 12 large-scale specimens are reported where the primary variables included the a/d ratio, reinforcement ratio, member height, and concrete strength. The results showed that an arch mechanism was able to form in FRP reinforced concrete beams having a/d 2.1. A strut and tie modelling procedure adapted from CSA A23.3-04 was capable of accurately predicting the capacity of FRP reinforced concrete deep beams containing no web reinforcement while sectional shear models gave poor, but conservative, predictions.Structural Engineering
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Ashour, Ashraf F., C. T. Morley, and N. K. Subedi. "Reinforced concrete two-span continuous deep beams." 2002. http://hdl.handle.net/10454/867.
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Yang, Keun-Hyeok, and Ashraf F. Ashour. "Influence of section depth on the structural behaviour of reinforced concrete continuous deep beams." 2007. http://hdl.handle.net/10454/863.
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YesAlthough the depth of reinforced concrete deep beams is much higher than that of slender beams, extensive existing tests on deep beams have focused on simply supported beams with a scaled depth below 600 mm. In the present paper, test results of 12 two-span reinforced concrete deep beams are reported. The main parameters investigated were the beam depth, which is varied from 400 mm to 720 mm, concrete compressive strength and shear span-tooverall depth ratio. All beams had the same longitudinal top and bottom reinforcement and no web reinforcement to assess the effect of changing the beam depth on the shear strength of such beams. All beams tested failed owing to a significant diagonal crack connecting the edges of the load and intermediate support plates. The influence of beam depth on shear strength was more pronounced on continuous deep beams than simple ones and on beams having higher concrete compressive strength. A numerical technique based on the upper bound analysis of the plasticity theory was developed to assess the load capacity of continuous deep beams. The influence of the beam depth was covered by the effectiveness factor of concrete in compression to cater for size effect. Comparisons between the total capacity from the proposed technique and that experimentally measured in the current investigation and elsewhere show good agreement, even though the section depth of beams is varied.
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Chen, Jia-Hong, and 陳佳鴻. "Shear Strength of RC T-Sectional Deep Beams." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/94624990316094979887.
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碩士國立中央大學
土木工程研究所
95
According to ACI 318-02, the RC beam with a / h ≦ 2.0 or a / d ≦ 2.5 so called as deep beams. The code suggested that the shear strength of deep beams be calculated using strut and tie model, and using the traditional experimental formula for the shear strength of normal-span beam. This study discusses the effect of three types of strut and tie model methods to analyze the tested deep beams. Meanwhile, these models applied to the prediction on not only the rectangular sectional beams but also T-sectional beams. Experiment specimens were made according to different ratios of a / d. That is, 8 rectangular beams and 10 T-beams were provided for testing The transverse reinforcement has two type of arrangement. One has no transverse reinforcement and the other has transverse and horizontal shear reinforcement designed according to ACI code. The experimental result shoes that prediction on rectangular beam and T-beams using softened strut and tie model is more accurate It also was found that the flanges contributed to some amount of shear strength of deep beams. The prediction results might not be accurate, if engineers did not consider the contribution of slab flanges for shear strength evaluation.
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Chen, Yu-Jen, and 陳佑任. "Shear Behavior of Steel Reinforced Concrete Deep Beams." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/59661100075851132644.
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碩士國立臺灣科技大學
營建工程系
89
The aim of this study is the shear strength behavior of the steel reinforced concrete (SRC) deep beams. Thirteen simply-supported beams were tested to failure by two-point monotonic loading. The varied parameters include depth of web, thickness of web, debonding of steel, and end anchorage of steel. The measured shear strength were compared with the computed values by the AISC-LRFD superposition method, the AIJ superposition method, and the softened strut-and-tie method. The ultimate load-carrying capacities were observed to be controlled by the web compression failure which is defined as the crushing of concrete within the diagonal strut at the upper end. The softened strut-and-tie method was found to yield the accurate strength estimation as well as the failure mechanism.
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Yang, Keun-Hyeok, and Ashraf F. Ashour. "Load capacity of reinforced concrete continuous deep beams." 2008. http://hdl.handle.net/10454/6245.
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Most codes of practice, such as EC2 and ACI 318-05, recommend the use of strut-and-tie models for the design of reinforced concrete deep beams. However, studies on the validity of the strut-and-tie models for continuous deep beams are rare. This paper evaluates the strut-and-tie model specified by ACI 318-05 and mechanism analysis of the plasticity theory in predicting the load capacity of 75 reinforced concrete continuous deep beams tested in the literature. The influence of such main parameters as compressive strength of concrete, shear span-to-overall depth ratio, main longitudinal bottom reinforcement, and shear reinforcement on the load capacity is also investigated using both methods and experimental results. Experimental results were closer to the predictions obtained from the mechanism analysis than the strut-and-tie model. The strut-and-tie model highly overestimated the load capacity of continuous deep beams without shear reinforcement.
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Yang, Keun-Hyeok, and Ashraf F. Ashour. "Aggregate interlock in lightweight concrete continuous deep beams." 2010. http://hdl.handle.net/10454/7562.
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yesThere are very few, if any, available experimental investigations on aggregate interlock capacity along diagonal cracks in lightweight concrete deep beams. As a result, the shear design provisions including the modification factor of ACI 318-08 and EC 2 for lightweight concrete continuous deep beams are generally developed and validated using normal weight simple deep beam specimens. This paper presents the testing of 12 continuous beams made of all-lightweight, sand-lightweight and normal weight concrete having maximum aggregate sizes of 4, 8, 13 and 19 mm. The load capacities of beams tested are compared with the predictions of strut-and-tie models recommended in ACI 318-08 and EC 2 provisions including the modification factor for lightweight concrete. The beam load capacity increased with the increase of maximum aggregate size, though the aggregate interlock contribution to the load capacity of lightweight concrete deep beams was less than that of normal weight concrete deep beams. It was also shown that the lightweight concrete modification factor in EC 2 is generally unconservative, while that in ACI 318-08 is conservative for all-lightweight concrete but turns to be unconservative for sand-lightweight concrete with a maximum aggregate size above 13 mm. The conservatism of the strut-and-tie models specified in ACI 318-08 and EC 2 decreased with the decrease of maximum aggregate size, and was less in lightweight concrete deep beams than in normal weight concrete deep beams.
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洪浩傑. "Shear Behavior of Steel Reinforced Concrete Deep Beams." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/76149783165093830469.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
91
The aim of this study is the shear strength behavior of the steel reinforced concrete (SRC) deep beams. Sixteen simply-supported beams were tested to failure by two-point monotonic loading. The varied parameters include strength of web material, types of gaps on the web, diagonal steel plate on compression direction, stiffness on the web, and position of steel. The measured shear strength was compared with the computed values by the ACI-AISC superposition method, the softened strut-and-tie-AISC superposition method, and the softened strut-and-tie method. The ultimate load-carrying capacities were observed to be controlled by the web compression failure which is defined as the crushing of concrete within the diagonal strut at the upper end. The softened strut-and-tie-AISC superposition method was found to yield the accurate strength estimation as well as the failure mechanism.
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Kah-Laun, Hong, and 洪克倫. "Shear Behavior of High Strength Concrete Deep Beams." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/64616202051598489846.
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