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Baczkowski, Bartlomiej Jan. "Steel fibre reinforced concrete coupling beams /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202007%20BACZKO.
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Chang, Peter. "Fracture characteristics of reinforced concrete beams." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65925.
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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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Chana, Palvinder Singh. "Shear failure of reinforced concrete beams." Thesis, University College London (University of London), 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282869.
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Fang, Libin. "Shear enhancement in reinforced concrete beams." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/25113.
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The shear failure of reinforced concrete beams has been widely investigated over many years. Despite this, there is no consensus on the relative importance of the underlying mechanisms of shear resistance. The main objective of this thesis is to develop improved design guidelines for shear enhancement in beams with multiple concentrated loads applied on their upper side within a distance of 2d from the edge of supports (where d is the beam effective depth). The research involves a combination of laboratory testing, nonlinear finite element analysis and analytical work. Many tests have been carried out on beams with single point loads within 2d of supports but only a handful on beams with multiple point loads within 2d of supports. This is a significant omission since such loading commonly arises in practice. The author carried out a series of tests on beams loaded with up to two point loads within 2d of supports. The tests were designed to investigate the influences on shear strength of loading arrangement, cover and bearing plate dimensions. The latter two were varied to investigate the underlying realism of key assumptions implicit in the Strut and Tie Modelling (STM) technique. Detailed measurements were made of the kinematics of the critical shear crack. These measurements were used to assess the relative contributions of aggregate interlock, dowel action and the flexural compressive zone to shear resistance. Novel STMs are proposed for modelling shear enhancement in simply supported and continuous beams. NLFEA is used to assist in the development of the STM. The STM are validated with test data and are shown to give reasonable strength predictions that are of comparable accuracy to the author's NLFEA. STM gives particularly good predictions of shear resistance if the strut strengths are calculated in accordance with the recommendations of the modified compression field theory rather than the recommendations of Eurocode 2, which can result in strength being overestimated. However, the STM are shown to overestimate the influences of bearing plate dimensions and cover on shear resistance.
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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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Barris, Peña Cristina. "Serviceability behaviour of fibre reinforced polymer reinforced concrete beams." Doctoral thesis, Universitat de Girona, 2011. http://hdl.handle.net/10803/7772.
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El uso de materiales compuestos de matriz polimérica (FRP) emerge como alternativa al hormigón convencionalmente armado con acero debido a la mayor resistencia a la corrosión de dichos materiales. El presente estudio investiga el comportamiento en servicio de vigas de hormigón armadas con barras de FRP mediante un análisis teórico y experimental. Se presentan los resultados experimentales de veintiséis vigas de hormigón armadas con barras de material compuesto de fibra de vidrio (GFRP) y una armada con acero, todas ellas ensayadas a flexión de cuatro puntos. Los resultados experimentales son analizados y comparados con algunos de los modelos de predicción más significativos de flechas y fisuración, observándose, en general, una predicción adecuada del comportamiento experimental hasta cargas de servicio. El análisis de sección fisurada (CSA) estima la carga última con precisión, aunque se registra un incremento de la flecha experimental para cargas superiores a las de servicio. Esta diferencia se atribuye a la influencia de las deformaciones por esfuerzo cortante y se calcula experimentalmente.Se presentan los aspectos principales que influyen en los estados límites de servicio: tensiones de los materiales, ancho máximo de fisura y flecha máxima permitida. Se presenta una metodología para el diseño de dichos elementos bajo las condiciones de servicio. El procedimiento presentado permite optimizar las dimensiones de la sección respecto a metodologías más generales.
Fibre reinforced polymer (FRP) bars have emerged as an alternative to steel for reinforced concrete (RC) elements in aggressive environments due to their non-corrosive properties. This study investigates the short-term serviceability behaviour of FRP RC beams through theoretical and experimental analysis. Twenty-six RC beams reinforced with glass-FRP (GFRP) and one steel RC beam are tested under four-point loading. The experimental results are discussed and compared to some of the most representative prediction models of deflections and cracking for steel and FRP RC finding that prediction models generally provide adequate values up to the service load. Additionally, cracked section analysis (CSA) is used to analyse the flexural behaviour of the specimens until failure. CSA estimates the ultimate load with accuracy, but it underestimates the experimental deflection beyond the service load level. This increment is mainly attributed in this work to shear induced deflection and it is experimentally calculated.
A discussion on the main aspects of the SLS of FRP RC is introduced: the stresses in materials, maximum crack width and the allowable deflection. A methodology for the design of FRP RC at the serviceability requirements is presented, which allows optimizing the overall depth of the element with respect to more generalised methodologies.
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Lam, Wai-yin. "Plate-reinforced composite coupling beams experimental and numerical studies /." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37311797.
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Svecová, Dagmar. "Behaviour of concrete beams reinforced withFRP prestressed concrete prisms." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0006/NQ42809.pdf.
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Ball, Ryan. "Experimental analysis of composite reinforced concrete beams." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1177002341.
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Al-Azzawi, Bakr. "Fatigue of reinforced concrete beams retrofitted with ultra-high performance fibre- reinforced concrete." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/108101/.
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Concrete structures deteriorate over time due to different reasons and thus may not perform their function satisfactorily. Repair and rehabilitation of deteriorated concrete structures is often preferred over demolition and rebuilding for economic reasons. Various metallic and nonmetallic materials have been used in the past for repair and rehabilitation. These materials have advantages and disadvantages. The latter are connected with the mismatch in the properties of these materials with the material of the structure being repaired which often resulted in unwanted failure modes, e.g. delamination. For this reason, new cement-based ultra-high performance reinforced with steel fibres repair materials have been developed in the last two decades, which restore (and even enhance) the structural response and improve the durability of repaired concrete structures. One such ultra-high-performance fibre-reinforced concrete material is CARDIFRC. It is characterized by very high compressive strength, high tensile /flexural strength, and high energy-absorption capacity. However, it is very expensive and thus industrially uncompetitive due to the very high cost of thin brass-coated steel fibres used in it. It is therefore important to develop a version of CARDIFRC that is industrially competitive. This is one of the objectives of this research. An ultra-high-performance fibre-reinforced concrete (UHPFRC) has been developed that is far less expensive than CARDIFRC and at the same time self-compacting. The steps necessary to achieve this have been described in this work. In addition, a full mechanical and fracture characterisation (i.e. size-independent fracture energy and the corresponding bi-linear stress-crack opening relationship) of this UHPFRC is presented. A nonlinear cracked hinge model has been used to back calculate the stress-crack opening relation of this material in an inverse manner from the test data. The second objective of this research concerns the flexural fatigue behaviour of this new UHPFRC. Tests have been conducted under several stress amplitude ranges. It has been found that the distribution of fibres plays a vital role in its fatigue resistance. Regions with few or no fibres can drastically reduce its fatigue life. As expected, non-zero mean stress leads to a significant reduction in the fatigue life of a material compared to cyclic loading with zero mean. The variation in compliance during cyclic loading has been used to estimate the expected fatigue life under a given cyclic load range, since the tests were terminated at one million cycles. The third objective of this research concerns the flexural fatigue behaviour of RC beams retrofitted with precast strips of this self-compacting UHPFRC on the tension face. Fatigue tests under several stress amplitude ranges have shown that this UHPFRC is an excellent retrofit material under fatigue loading. Again, the variation in compliance during the fatigue loading has been used to estimate the expected fatigue life for retrofitted RC beams.
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趙作周 and Zuozhou Zhao. "Nonlinear behaviour of reinforced concrete coupling beams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31243927.
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Zhao, Zuozhou. "Nonlinear behaviour of reinforced concrete coupling beams /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23589395.
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Yapa, Hiran Deshantha. "Optimum shear strengthening of reinforced concrete beams." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/265518.
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External prestressed carbon fibre reinforced polymer (CFRP) straps can be used to strengthen shear deficient reinforced concrete (RC) structures. The strengthening system is associated with a number of parameters including the number of straps, strap locations, strap stiffness, and strap prestress. The initial goal of this research was to identify the optimum values for these parameters in order to design an efficient and effective shear retrofitting system. The shear friction theory (SFT) and modified compression field theory (MCFT) were identified as potential predictive theories to model the shear behaviour of RC beams retrofitted with CFRP straps. Possible modifications to the theories to reflect CFRP prestressed straps were investigated. Two popular optimisation algorithms namely the genetic algorithm (GA) and particle swarm optimisation (PSO) were coded and tested with six test functions. These algorithms were used to find the optimum shear retrofitting configurations and also to reduce the computational cost associated with the SFT and MCFT evaluations. An experimental investigation was carried out to validate the SFT and MCFT predictions for various CFRP strap configurations. The investigation consisted of an unstrengthened control beam and five CFRP strengthened beams. The shear behaviour of the beams was significantly influenced by the CFRP strap configurations. A critical load level where the beam stiffness started to deteriorate significantly was identified. It was found that there was a correlation between this load level and the yielding of the internal shear links and a rapid increase in crack openmg. The SFT and MCFT were validated using the experimental results. The peak shear capacities predicted using the SFT were more consistent with the stiffness deteriorating loads identified in the experimental investigation than with the ultimate loads of the beams. The reinforcement forces and crack opening values found from the SFT were consistent with the experimental results. The MCFT predicted the total shear response, ultimate shear capacity, crack opening, and internal and external reinforcement forces in the beams. The accuracy of the MCFT predictions reduced slightly when either the strap configuration was highly nonuniforrn or the initial prestress level in the straps was relatively low. The shear link yielding load levels predicted by the MCFT were found to be similar to the SFT predictions. By using the coded optimisation algorithms in combination with the SFT or MCFT, the optimum CFRP strap configurations were found for a selected case study. Both theories predicted an offset for the optimum strap locations from the locations associated with equal spacings along the shear span. A reasonable agreement between the SFT and MCFT predictions for the optimum shear strengths and strap locations was observed. A parametric study demonstrated that the concrete strength, internal shear link locations, beam depth, and shear span to depth ratio of the beam do not significantly influence the optimum strengthening configurations for the CFRP strap system. External prestressed carbon fibre reinforced polymer (CFRP) straps can be used to strengthen shear deficient reinforced concrete (RC) structures. The strengthening system is associated with a number of parameters including the number of straps, strap locations, strap stiffness, and strap prestress. The initial goal of this research was to identify the optimum values for these parameters in order to design an efficient and effective shear retrofitting system. The shear friction theory (SFT) and modified compression field theory (MCFT) were identified as potential predictive theories to model the shear behaviour ofRC beams retrofitted with CFRP straps. Possible modifications to the theories to reflect CFRP prestressed straps were investigated. Two popular optimisation algorithms namely the genetic algorithm (GA) and particle swarm optimisation (PSO) were coded and tested with six test functions. These algorithms were used to find the optimum shear retrofitting configurations and also to reduce the computational cost associated with the SFT and MCFT evaluations. An experimental investigation was ca1Tied out to validate the SFT and MCFT predictions for various CFRP strap configurations. The investigation consisted of an unstrengthened control beam and five CFRP strengthened beams. The shear behaviour of the beams was significantly influenced by the CFRP strap configurations. A critical load level where the beam stiffness started to deteriorate significantly was identified. It was found that there was a correlation between this load level and the yielding of the internal shear links and a rapid increase in crack opening. The SFT and MCFT were validated using the experimental results. The peak shear capacities predicted using the SFT were more consistent with the stiffness deteriorating loads identified in the experimental investigation than with the ultimate loads of the beams. The reinforcement forces and crack opening values found from the SFT were consistent with the experimental results. The MCFT predicted the total shear response, ultimate shear capacity, crack opening, and internal and external reinforcement forces in the beams. The accuracy of the MCFT predictions reduced slightly when either the strap configuration was highly nonuniform or the initial prestress level in the straps was relatively low. The shear link yielding load levels predicted by the MCFT were found to be similar to the SFT predictions. By using the coded optimisation algorithms in combination with the SFT or MCFT, the optimum CFRP strap configurations were found for a selected case study. Both theories predicted an offset for the optimum strap locations from the locations associated with equal spacings along the shear span. A reasonable agreement between the SFT and MCFT predictions for the optimum shear strengths and strap locations was observed. A parametric study demonstrated that the concrete strength, internal shear link locations, beam depth, and shear span to depth ratio of the beam do not significantly influence the optimum strengthening configurations for the CFRP strap system.
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Fazio, Robert. "Flexural behaviour of corroded reinforced concrete beams." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29592.pdf.
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Sokolov, Aleksandr. "Tension stiffening model for reinforced concrete beams." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20100803_110628-45999.
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Modelling behaviour of cracked tensile concrete is a complicated issue. Due to bond with reinforcement, the cracked concrete between cracks carries a certain amount of tensile force normal to the cracked plane. Concrete adheres to rein-forcement bars and contributes to overall stiffness of the structure. The phe-nomenon, called tension-stiffening, has significant influence on the results of short-term deformational analysis. Assumption of a tension-stiffening law has great influence on numerical results of load – deflection behaviour of reinforced concrete members subjected to short – term loading. Under wrong assumption of this law, errors in calculated deflections, particularly for lightly members, may exceed 100 %. Most known tension-stiffening relationships relate average stresses to average strains. However, some experimental and theoretical investi-gations have shown that tension-stiffening may be affected by other parameters. The scientific supervisor of the thesis has proposed a tension-stiffening model depending on reinforcement ratio. This model has been developed using experi-mental data reported in the literature. Besides, concrete shrinkage effect was not taken into account. The main objective of this PhD dissertation is to propose a tension-stiffening law for bending RC members subjected to short-term loading with eliminated concrete shrinkage effect.Gelžbetonis yra kompozitinė medžiaga, kurios komponentai yra betonas ir plieninė armatūra. Kaip žinoma, betono stipris tempiant yra 10-20 kartų mažesnis nei stipris gniuždant. Atrodytų, kad tempiamojo betono įtaka, atlaikant įrąžas skerspjūvyje, yra nereikšminga. Iš tiesų, nustatant lenkiamųjų elementų stiprumą normaliniame pjūvyje, tempiamo betono įtempių galima nevertinti. Kita vertus, skaičiuojant įlinkius, neįvertinus tempiamojo betono įtakos, gali būti daroma didesnė nei 100 % paklaida. Adekvatus supleišėjusio tempiamojo betono įtakos įvertinimas, nustatant trumpalaike apkrova veikiamų gelžbetoninių elementų deformacijas, yra bene svarbiausia ir sudėtingiausia problema. Plyšio vietoje betonas negali atlaikyti tempimo įtempių, todėl visą įrąžą atlaiko armatūra. Kadangi plyšyje ir gretimuose pjūviuose armatūra praslysta betono atžvilgiu, kontakto zonoje atsiranda tangentiniai įtempiai. Šie įtempiai perduodami betonui, todėl jis atlaiko tempimo įtempius. Armatūros ir betono sąveika ruožuose tarp plyšių standina gelžbetoninį elementą. Supleišėjusio betono gebėjimas atlaikyti tempimo įtempius vadinama tempimo sustandėjimu (angl. tension stiffening). Šis efektas dažniausiai modeliuojamas supleišėjusio betono įtempių ir deformacijų diagrama, taikant vidutinių plyšių koncepciją. Tuomet neatsižvelgiama į diskrečius plyšius, o supleišėjęs betonas traktuojamas kaip ortotropinė medžiaga su pakitusiomis savybėmis. Dauguma tempimo sustandėjimo modelių įvertina betono įtempių... [toliau žr. visą tekstą]
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Fazio, Robert 1970. "Flexural behaviour of corroded reinforced concrete beams." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27219.
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This report presents the results of a laboratory investigation of the influence of the corrosion process on the flexural capacity such as strength, deflection and steel and concrete strains in reinforced concrete beams. Examination of the behaviour of crack development was also examined.Fourteen simply supported concrete beams were cast and subjected to two third point concentrated loads, increased monotonically until failure. The strength, strain and crack development data were recorded to assess the corrosion rate and its effect on the steel bars.
An electrochemical system was used to achieve the different corrosion levels. The specimens were immersed in a 5 percent of sodium chloride by weight of water for a period of one to thirty weeks. An initial voltage of 1 volt was impressed through the beams to initiate and to accelerate the corrosion process. A steel plate was immersed in the solution to act as a cathode and force the steel reinforced concrete beam to act as an anode.
The report discusses the defects and environmental factors influencing the corrosion process. (Abstract shortened by UMI.)
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羅文惠 and Man-wai Law. "Strain energy capacity of reinforced concrete beams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1987. http://hub.hku.hk/bib/B31207704.
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Tan, Chuan Ming. "Nonlinear vibrations of cracked reinforced concrete beams." Thesis, University of Nottingham, 2003. http://eprints.nottingham.ac.uk/28976/.
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Although a great deal of work in investigating the possibility of using linear vibration techniques to detect damage in bridges has been carried out over the past 25 years, there are still some major concerns, such as poor sensitivity of modal parameters to damage, requirement of baseline data, need of measuring excitation force as well as environmental effects. Nonlinearity in the vibration characteristics when the structure is damaged further complicates the problem and causes doubts on the feasibility of applying these techniques on actual structures. Understanding of the nonlinear behaviour is therefore crucial. The aim of the work presented herein is to improve the current understanding of the nonlinear vibration characteristics of reinforced concrete beams and to assess its importance to the subject of structural health monitoring of bridges. These non-linear vibration characteristics were studied by conducting harmonic excitation vibration tests on reinforced concrete beams at various damage levels. In order to detect and characterise the nonlinear behaviour, both linear and nonlinear system identification techniques were used. Results indicated that the responses of the tested beams showed marked softening behaviour and that this non-linear vibration behaviour varied with increasing damage. The restoring force surface technique was applied to the test data and results suggested that cracks in reinforced concrete beams never fully closed in the vibration cycle. Existing phenomenological models suggested by other researchers were investigated and compared with the experimental results. The study confirmed that a bilinear crack model would not be sufficient to replicate the observed vibrating cracked reinforced concrete beams' behaviour. Based on these phenomenological models, an empirical model was derived. Using the empirical crack model proposed, the author suggested a means of estimating the ratio of cracked and uncracked stiffness of a vibrating cracked reinforced concrete beam. The author further suggested a possible routine for structural health monitoring for reinforced concrete beam and stressed that it could be extended for more complicated structures, like bridges. To improve understanding of the nonlinearities in the vibration characteristics, a damage mechanics model of cracked reinforced concrete beam was suggested. Based on strain softening behaviour of concrete material under tensile force, the model is capable of including damage in the form of a moment rotation relationship over the cracked region. Results from the vibration analysis of the model were compared with experimental data.
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Houmsi, Ahmed. "Shear strength of reinforced concrete haunched beams." Thesis, University of Strathclyde, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241959.
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Hristova, Elena Hristova. "Residual strength of corroded reinforced concrete beams." Thesis, Sheffield Hallam University, 2006. http://shura.shu.ac.uk/19838/.
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Currently, much research is focused on the corrosion of reinforcement in concrete members. However, none addresses the problems associated with the residual strength of reinforced concrete beams exhibiting both main and shear reinforcement corrosion simultaneously. The aim of this research, therefore, was to determine the residual strength of corroded reinforced concrete beams where various degrees of reinforcement corrosion is present in both the main and shear reinforcement. This may provide a better understanding of the performance of deteriorated reinforced concrete beams in service. One of the main causes of concrete deterioration is corrosion of the steel reinforcement and thus a reduction of the residual service life. In general, corrosion of reinforcement is believed to affect the structural performance of concrete elements in two ways. Firstly, by reducing the rebar cross sectional area, and secondly, by loss of bond strength between the concrete and steel reinforcement and resulting growth of cracks due to the formation of corrosion products at concrete/reinforcement interface. The experimental programme was carried out to provide information on the loss of strength resulting from corrosion to the main and shear reinforcement. Corrosion was induced by means of external power supplies. The test programme was divided into three series. Series I was devised to determine the residual flexural strength of reinforced concrete beams where different diameters of main (high yield) reinforcement were subjected to varying degrees of accelerated corrosion (shear strength was provided by mild steel shear reinforcement which remained unaffected by corrosion). Series II was devised to determine the residual shear strength of reinforced concrete beams where the shear (mild steel) reinforcement was subjected to varying degrees of accelerated corrosion (flexural strength was provided by high yield steel which was protected from corrosion). Finally, Series III was devised to determine the residual strength of reinforced concrete beams where both the main (high yield) and shear (mild steel) reinforcement were simultaneously corroded and the effect of this on the performance of the beam was determined. In total, 116 beams were subjected to accelerated corrosion using an impressed current imposed on the reinforcement. Each beam was loaded to failure to determine the strength loss. Four degrees of corrosion were targeted, ranging from 0% (control) to 15%, in increments of 5%.The results of the laboratory tests determined the significance of both main and shear reinforcement corrosion on the performance of deteriorated reinforced concrete beams. In addition, simplified analytical equations were developed which may assist the engineer in assessing the residual strength of corroded reinforced concrete beams.
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Sas, Gabriel. "FRP shear strengthening of reinforced concrete beams." Doctoral thesis, Luleå tekniska universitet, Byggkonstruktion och -produktion, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25881.
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The shear failure mechanisms of flexural reinforced concrete (RC) members is highly complex; its precise details cannot be explained with simple analytical relationships, and are the topic of considerable scientific debate. The studies described and examined the three most used shear theories in the world – the fixed angle truss model (45°TM), the variable angle truss model (VAT), and modified compression field theory (MCFT). These three theories rest on the assumption that a beam loaded in shear behaves as a truss. However, this assumption is applied in different ways in various codes. In this thesis, three major standards, each of which uses a different implementation of these theories (CEN, 2005; ACI-318, 2008; CSA-A23.3, 2009), were used to predict the shear force capacity of a RC railway bridge that was strengthened in flexure with near surface mounted (NSM) carbon fibre reinforced polymers (CFRP) and then tested to failure. The data obtained in this test indicated that the codes underestimated the real shear behaviour of the bridge. There are some accepted reasons for such inaccuracies, namely the use of empirically derived equations in the ACI (2008) and CSA (2009) standards and the omission of the concrete contribution in CEN (2005). Moreover, the NSM reinforcement material used exhibits elastic behaviour until the point of failure; it was found that the use of such materials introduces further decreases the accuracy of the models’ predictions. The strains that developed in the area of the bridge where shear failure was expected were monitored throughout the test using a specially-developed photographic method. The results obtained with this method were promising, especially for research purposes, since it generated reliable data using relatively affordable tools.The use of FRP for shear strengthening introduces further complications to the problem of shear in reinforced concrete members because introduces two new failure modes: debonding at the concrete interface and fibre rupture of the FRP. Extensive research has been carried out on FRP shear strengthening around the world. Much of the data gathered in these studies has been compiled in a database. By analysing this large database, it was found that the effectiveness of FRP shear strengthening is influenced by many factors, including the properties of the FRPs, the FRP strengthening configuration used, the nature of the beam’s cross-section, the shear span to depth ratio, the presence of stirrups, and the nature of the tensile reinforcement. Analysis of this database also demonstrated that most of the studies reported in the literature had focused on investigating the influence of the properties of the FRPs and the different configuration systems, and that the other factors mentioned above have been sparsely investigated if not totally ignored. The strengthening configuration and the amount of fibres influence the failure mode of the FRP and the shear force that it can carry. It appears that the side-bonded and the U-wrapped configurations are most prone to failure by debonding. This is consistent with the findings of various small experimental programs, and was confirmed by analysis of the larger dataset. These findings are relevant because failure of the FRP by debonding is more complex mechanism than is the rupture of the fibres mechanism. As is shown in this thesis, the extent to which the FRP variables (properties and strengthening configuration) can affect the point at which failure occurs and the mode by which it happens is dependent on the quantity of stirrups and tensile reinforcement in the beam, to the position of the load in relation to the size of the cross section (shear span to depth ratio), the type of strengthening configuration, the concrete and FRP properties. For design purposes, it is important to predict the shear failure of FRP shear strengthened beams with as much accuracy as possible. Therefore, a design model for debonding of the shear strengthening of concrete beams with FRP was developed and the limitations of the truss model analogy were highlighted. The fracture mechanics approach was used to analyse the behaviour of the bond between the FRP composites and the concrete. In this model, of the parameters examined, the fracture energy of concrete and the axial rigidity of the FRP are considered to be the most important. The effective strain in the FRP when debonding occurs was determined and the limitations of the anchorage length over the cross section were analysed; ultimately, a simple iterative method for shear debonding was proposed. Since the model’s predictions were considered satisfactory but not really precise, an extensive review of the literature was conducted. All of the significant theoretical models for predicting the shear capacity of FRP strengthened RC beams that have been reported over the years were analysed and commented on, and their predictions were compared to the results recorded in a preliminary experimental database. The predictions of the models that are most widely used in design were compared to the experimental results reported in the database; the model developed by the author was evaluated alongside these more established models. All of the models, including that presented in this thesis, were found to generate inaccurate predictions, but two models have been calibrated so as to provide safe estimates of the FRP shear capacity. Finally a new model for FRP shear strengthening was proposed for use in engineering. The new model was developed on the basis of an analysis of the contents of the database of experimental findings. The model incorporates several design equations adopted from various models and is set up for engineering use. The predictions of the shear force carried by the FRP strengthening material are found to be conservative.Godkänd; 2011; 20110328 (gabsas); DISPUTATION Ämnesområde: Konstruktionsteknik/Structural Engineering Opponent: Professor Giorgio Monti, University of Rome, Italy Ordförande: Professor Björn Täljsten, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Fredag den 29 april 2011, kl 13.00 Plats: F1031, Luleå tekniska universitet
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Law, Man-wai. "Strain energy capacity of reinforced concrete beams /." [Hong Kong : University of Hong Kong], 1987. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12228175.
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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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Al-lami, Karrar Ali. "Experimental Investigation of Fiber Reinforced Concrete Beams." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2296.
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Shear strength of fiber reinforced concrete beams was studied in this research project. Three types of fibers were examined: hooked-end steel fiber, crimped-steel fiber, and crimped-monofilament polypropylene fibers. The experimental program included five beam specimens. Two of the beams were control specimens in which one was reinforced with minimum shear reinforcement according to ACI 318, while the other one did not have any shear reinforcement. Each one of the other three specimens was reinforced with one of the above mentioned fibers by 1% volumetric ratio. In addition to the beam specimens, three prisms were also made for each type fiber to determine their toughness.
The aim of this research was to investigate the following questions for medium-high concrete strength 1) to evaluate the effectiveness of each type of fibers on the shear strength, 2) to investigate the shear strength, toughness, crack patterns and near ultimate load crack width of each beam, and 3) to determine if using 1% volumetric ratio of fibers as shear reinforcement in beams would provide adequate strength and stiffness properties comparable to reinforcing steel used as minimum shear reinforcement.
The results showed that all three types of fibers increased the shear capacity of the beam specimens more than the beam reinforced with minimum shear reinforcement. Moreover, some of the fibers used could shift the type of failure from a pure shear failure to a combined flexural-shear or pure flexural failure.
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Abdulmajid, Amin Ali Ahmed. "Strengthening of reinforced concrete beams using carbon fibre reinforced plastic." Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/1998.
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FILHO, JULIO JERONIMO HOLTZ SILVA. "CARBON FIBER REINFORCED POLYMER TORSION STRENGTHENING OF REINFORCED CONCRETE BEAMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10658@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOEste estudo teórico-experimental analisa o comportamento até a ruptura de vigas de concreto armado reforçadas externamente à torção com compósitos de fibras de carbono (CFC). No programa experimental, sete vigas de concreto armado, com seção transversal de 20 cm x 40 cm e 420 cm de comprimento, com mesma armadura de aço longitudinal e transversal e concreto com mesma resistência à compressão, foram ensaiadas até a ruptura. As vigas testadas foram divididas em três séries, sendo uma viga de referência sem reforço, três vigas com reforço transversal externo e três vigas com reforço externo transversal e longitudinal. Para a realização dos ensaios foi montada uma estrutura auxiliar de aço capaz de transferir às vigas a solicitação de torção pura. No estudo teórico foram desenvolvidas duas formulações. A primeira formulação, baseada no modelo da treliça espacial generalizada com abrandamento de tensões, apresenta uma sistemática para traçado da curva momento torçor x ângulo de torção por unidade de comprimento de vigas de concreto armado reforçadas à torção. A segunda formulação, fundamentada no modelo da Analogia da Treliça Espacial de acordo com a filosofia de dimensionamento do Eurocode 2, apresenta uma sistemática para dimensionamento de reforço com CFC . As duas metodologias adotam um modelo para determinação da aderência entre o substrato de concreto e o reforço. A inclusão da aderência nos modelos desenvolvidos é de grande importância porque em geral a ruptura do elemento estrutural ocorre devido ao descolamento do CFC. Os resultados experimentais obtidos nos testes das vigas foram utilizados para validar as duas formulações teóricas desenvolvidas. Os resultados experimentais apresentaram boa aproximação quando comparados com os modelos propostos. Verificou-se que todas as vigas reforçadas apresentaram um acréscimo de resistência à torção em torno de 40% em relação à viga de referência. Verificou-se que, após a fissuração, as vigas reforçadas apresentaram perda de rigidez inferior à da viga de referência. Observou-se que o ângulo da fissura medido experimentalmente, o ângulo de inclinação calculado pelo estado de deformação e o ângulo de inclinação calculado pelo estado de tensão da viga apresentaram valores próximos para cada viga.
A theoretical-experimental research on the torsional behavior up to failure of reinforced concrete beams strengthened with external carbon fiber composites (CFC) was carried out. The experimental study comprises a series of seven reinforced concrete beams with the same compressive strength of concrete loaded to failure and subjected to torsion. The beams dimensions were 20 cm x 40 cm x 420 cm. The test specimens had the same internal steel reinforcement. The beams were divided in three series: the reference beam without strengthening; three beams with the external strengthening applied transversally and three beams with the external strengthening applied transversally and longitudinally. For the accomplishment of the tests an auxiliary steel structure was mounted, capable to transfer to the beams the pure torsion moment. In the theoretical study two analytical procedures were developed. The first formulation, based on the softened space truss model for torsion, presents a systematic to obtain the curve torsion moment x torsion angle per length unit of the reinforced concrete beams with CFC torsion strengthening. The second systematic, based on the Space Truss Model in accordance with the Eurocode 2, presents the design of the CFC strengthening. Both methodologies adopt the Chen and Teng bond model between concrete and CFC. The consideration of the bond in the developed models is very important because the failure of the concrete members often occurs from debonding of the CFC. The experimental results from the beams tests were used to validate the two analytical procedures. Good agreement was obtained with the experimental and analytical results. For all the strengthened beams the average values of torsion strength were increased by 40% when compared to the reference beam. After cracking, the loss of rigidity in the strengthened beams was lower then in the reference beam. The cracking angle experimentally measured and the strut angles evaluated by strain state and stress state presented close values.
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羅紹湘 and Siu-seong Law. "Failure of reinforced concrete beam-columns." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31207327.
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Law, Siu-seong. "Failure of reinforced concrete beam-columns /." [Hong Kong : University of Hong Kong], 1985. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12263631.
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Yang, Zhenjun. "Discrete crack modelling of plated concrete beams." Thesis, University of Wolverhampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247276.
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Strengthening reinforced concrete (RC) beams using externally bonded steel plates or fibre reinforced polymer (FRP) composites to enhance their structural performance has been paid great attention in recent years. RC beams strengthened in such way (plated RC beams) have many failure modes different from those of conventional concrete beams. A better understanding on the behaviour of the strengthened beams is essential for safe and economical design of strengthening schemes. This thesis presents research into discrete crack modelling of plated RC beams using a specialised computer program developed in this research. A key factor affecting the behaviour and reliability of strengthened concrete structures is the bond strength between the steel or FRP plate and the concrete substrate. A literature review has shown that many different methods have been used to test this bond strength. An extensive analysis on the stress distribution in various test set-ups was conducted using the finite element analysis (FEA). Results show that stress distribution can be significantly different among different set-ups, for similar materials and geometry. The bond strength and failure modes can be significantly dependent on the adopted test method. These suggest that it is important to develop a standard test method so that test results from different sources are comparable. The research studied a number of issues in using a discrete crack model based FEA method to model the behaviour of plated RC beams: Firstly, extensive FEA carried out in this research shows that the accuracy of predicted stress intensity factors may be significantly improved by adding a rosette around the crack tip in linear elastic fracture mechanics (LEFM) problems, but the optimum rosette size is problem dependent. In order to avoid this uncertainty, a new procedure was devised which resulted in good predictions even for very coarse meshes. Secondly, a mixed-mode discrete crack LEFM based FEA model was developed to model the behaviour of plated RC beams. Automatic multiple crack propagation during the whole loading process until the failure of the structure was modelled. Simulation of the concrete cover separation failure mode has been particularly success. Numerical results confirmed that the bonding of a plate leads to smaller and more closely spaced cracks than the un-strengthened beam. For plated beams, the cracking can have significant effect on the stress distribution in the FRP plates. The length of the plate has a significant effect on the failure mode. Finally, 16 numerical strategies were compared for solving problems associated with sharp snap-back behaviour encountered in modelling discrete crack propagation in concrete beams using non-linear fracture mechanics. A four-point single notched shear beam with nonlinear interface elements representing the discrete cracks was used for this purpose. The results show that the effectiveness and efficiency may vary considerably from one to another, with the local arc-length based procedures in conjunction with tangential stiffness strategy and reversible unloading model being the most robust.
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Svecova, Dagmar Carleton University Dissertation Engineering Civil and Environmental. "Behaviour of concrete beams reinforced with FRP prestressed concrete prisms." Ottawa, 1998.
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Pan, Jinlong. "Crack-induced debonding failure in fiber reinforced plastics (FRP) strengthened concrete beams : experimental and theoretical analysis /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202005%20PAN.
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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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Siu, Wing-ho. "Flexural strengthening of reinforced concrete beams by bolted side plates." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43278735.
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Mohamed, Ali M. S. "Peeling of plates adhesively bonded to reinforced concrete beams /." Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phm6968.pdf.
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Boyd, Andrew James. "Rehabilitation of reinforced concrete beams with sprayed glass fiber reinforced polymers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61068.pdf.
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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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Deng, Jiangang. "Durability of carbon fiber reinforced polymer (CFRP) repair/strengthening concrete beams." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1663060011&sid=2&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Cladera, Bohigas Antoni. "Shear design of reinforced high-strength concrete beams." Doctoral thesis, Universitat Politècnica de Catalunya, 2003. http://hdl.handle.net/10803/6155.
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Aunque el hormigón de alta resistencia se está utilizando de manera creciente en los últimos años para la construcción de estructuras, la norma Española vigente, la Instrucción EHE, sólo abarca hormigones de resistencias características a compresión inferiores a 50 MPa. El aumento de resistencia del hormigón está directamente asociado a una mejora en la mayoría de sus prestaciones, especialmente de la durabilidad, aunque también produce un aumento en la fragilidad y una disminución de la rugosidad de las fisuras, lo que afecta de forma muy especial a la resistencia a cortante.El objetivo principal de este trabajo es contribuir al avance del conocimiento del comportamiento frente a la rotura por cortante de vigas de hormigón de alta resistencia. Para ello, y en primer lugar, se ha llevado a cabo una extensa revisión del estado actual del conocimiento de la resistencia a cortante, tanto para hormigón convencional como para hormigón de alta resistencia, así como una profunda investigación de campañas experimentales anteriores.
Se ha realizado una campaña experimental sobre vigas de hormigón de alta resistencia sometidas a flexión y cortante. La resistencia a compresión del hormigón de las vigas variaba entre 50 y 87 MPa. Las principales variables de diseño eran la cuantía de armadura longitudinal y transversal. Los resultados obtenidos experimentalmente han sido analizados para estudiar la influencia de las distintas variables en función de la resistencia a compresión del hormigón.
Con el objetivo de tener en cuenta, no sólo los resultados de nuestros ensayos, sino también la gran cantidad de información disponible en la bibliografía técnica, se ha preparado una base de datos con vigas de hormigón convencional y de alta resistencia a partir del banco de datos de la Universidad de Illinois. Los resultados empíricos han sido comparados con los cortantes últimos calculados según la Instrucción EHE, las especificaciones AASHTO LRFD, el Código ACI 318-99 y el programa Response-2000, basado en la teoría modificada del campo de compresiones.
Se han construido dos Redes Neuronales Artificiales (RNA) para predecir la resistencia a cortante en base a la gran cantidad de resultados experimentales. La principal característica de las RNA es su habilidad para aprender, mediante el ajuste de pesos internos, incluso cuando los datos de entrada y salida presentan un cierto nivel de ruido. Con los resultados de la RNA se ha realizado un análisis paramétrico de cada variable que afecta la resistencia última a cortante.
Se han propuesto nuevas expresiones que tienen el cuenta el comportamiento observado para el diseño frente al esfuerzo cortante de vigas tanto de hormigón convencional como de alta resistencia con y sin armadura a cortante, así como una nueva ecuación para la determinación de la armadura mínima a cortante. Las nuevas expresiones presentan resultados que se ajustan mejor a los resultados experimentales que los obtenidos mediante la utilización de las normativas vigentes.
Finalmente se han planteado varias sugerencias de futuras líneas de trabajo, que son resultado de la propia evolución del conocimiento sobre el tema de estudio durante el desarrollo de esta tesis.
Although High-Strength Concrete has been increasingly used in the construction industry during the last few years, current Spanish Structural Concrete code of practice (EHE) only covers concrete of strengths up to 50 MPa. An increase in the strength of concrete is directly associated with an improvement in most of its properties, in special the durability, but this also produces an increase in its brittleness and smoother crack surfaces which affects significantly the shear strength.
The aim of this research is to enhance the understanding of the behaviour of high-strength concrete beams with and without web reinforcement failing in shear. In order to achieve this objective, an extensive review of the state-of-the-art in shear strength for both normal-strength and high-strength concrete beams was made, as well as in-depth research into previous experimental campaigns.
An experimental programme involving the testing of eighteen high-strength beam specimens under a central point load was performed. The concrete compressive strength of the beams at the age of the tests ranged from 50 to 87 MPa. Primary design variables were the amount of shear and longitudinal reinforcement. The results obtained experimentally were analysed to study the influence of those parameters related to the concrete compressive strength.
With the aim of taking into account, in addition to the results of our tests, the large amount of information available, a large database was assembled based on the University of Illinois Sheardatabank for normal-strength and high-strength concrete beams. These test results were compared with failure shear strengths predicted by the EHE Code, the 2002 Final Draft of EuroCode 2, the AASHTO LRFD Specifications, the ACI Code 318-99, and Response-2000 program, a computer program based on the modified compression field theory.
Furthermore, two Artificial Neural Networks (ANN) were developed to predict the shear strength of reinforced beams based on the database beam specimens. An ANN is a computational tool made up of a number of simple, highly-interconnected processing elements that constitute a network. The main feature of an ANN is its ability to learn, by means of adjusting internal weights, even when the input and output data present a degree of noise. Based on the ANN results, a parametric study was carried out to study the influence of each parameter affecting the failure shear strength.
New expressions are proposed, taking into account the observed behaviour for the design of high-strength and normal-strength reinforced concrete beams with and without web reinforcement. A new equation is given for the amount of minimum reinforcement as well. The new expressions correlate with the empirical tests better than any current code of practice.
Finally, as a natural corollary to the evolution of our understanding of this field, some recommendations for future studies are made.
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Kalkan, Ilker. "Lateral torsional buckling of rectangular reinforced concrete beams." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31788.
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Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2010.Committee Chair: Zureick Abdul-Hamid; Committee Member: Ellingwood, Bruce R.; Committee Member: Kahn, Lawrence F.; Committee Member: Kardomateas, George A.; Committee Member: Will, Kenneth M. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Yao, Zhong, and 姚钟. "Nonlinear finite element analysis of reinforced concrete beams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B5090002X.
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A nonlinear finite element program to simulate the behavior of reinforced concrete (RC) members under the action of monotonic increasing loading has been developed. The nonlinear response of the RC members is mainly due to the nonlinear material characteristics including nonlinear biaxial stress-strain relations and cracking of concrete and yielding of steel reinforcement.
A constitutive model of concrete under biaxial stress state is adopted in this thesis. In this model, concrete fails and critical cracks occur when the tensile strain of concrete exceeds the limiting tensile strain. The complete stress-strain relationship of concrete under compression and tension are employed in the study to investigate the post-peak behavior of reinforced concrete members. An elaborate cracking model has been implemented which allows concrete to crack in one or two directions. The tension stiffening effect of cracked concrete is also incorporated into this model by including a descending branch in the stress-strain curve of concrete under tension. Other nonlinear effects such as crushing of concrete in compression and yielding or strain hardening of steel reinforcement are also taken into account.
A nonlinear finite element program was developed, in which the abovementioned nonlinear effects have all been included in modeling the reinforced concrete structures. The nonlinear equations of equilibrium are solved using an incremental-iterative technique performed under displacement control. The validity of the model including the confinement effect of secondary reinforcements has been examined by analyzing three reinforced concrete beams. The performance of the numerical model was assessed by comparing results with those from available experimental data.published_or_final_version
Civil Engineering
Master
Master of Philosophy
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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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Abdullah, Mohd Sabri. "Reinforced concrete beams with steel plates for shear." Thesis, University of Dundee, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342881.
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Teo, W. T. "Adjusted reinforcement for reinforced concrete beams in shear." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419409.
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Azizi, Abdul R. "Modelling moment redistribution in continuous reinforced concrete beams." Thesis, Durham University, 1996. http://etheses.dur.ac.uk/1578/.
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Rahman, S. M. Hasanur. "Flexural behavior of GFRP-reinforced concrete continuous beams." American Society of Civil Engineers, 2016. http://hdl.handle.net/1993/31905.
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In this study, a total of twelve beams continuous over two spans of 2,800 mm each were constructed and tested to failure. The beams were divided into two series. Series 1 included six T-beams under symmetrical loading, while Series 2 dealt with six rectangular beams under unsymmetrical loading conditions. In Series 1, the test variables included material type, assumed percentage of moment redistribution, spacing of lateral reinforcement in flange, arrangement of shear reinforcement, and serviceability requirements. In Series 2, three different loading cases were considered, I) loading both spans equally, II) loading both spans maintaining a load ratio of 1.5 and III) loading one span only. Under the loading case II, the parameters of reinforcing material type, assumed percentage of moment redistribution and serviceability requirements were investigated.
The test results of both series showed that moment redistribution from the hogging to the sagging moment region took place in GFRP-RC beams which were designed for an assumed percentage of moment redistribution. In Series 1, the decrease of the stirrups spacing from 0.24d to 0.18d enhanced the moment redistribution percentage. Also, decreasing the spacing of lateral reinforcement in the flange from 450 to 150 mm improved the moment redistribution through enhancing the stiffness of the sagging moment region. In Series 2, the unsymmetrical loading conditions (loading case II and III) reduced the moment redistribution by reducing flexural stiffness in the heavily loaded span due to extensive cracking. Regarding serviceability in both series, the GFRP-RC beam designed for the same service moment calculated from the reference steel-RC beam, was able to meet the serviceability requirements for most types of the structural applications.February 2017
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McCarty, Colin Michael. "Behavior of Two-Span Continuous Reinforced Concrete Beams." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1219333577.
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James, Valontino Ruwhellon. "Fatigue Behaviour of CFRP Strengthened Reinforced Concrete Beams." Master's thesis, Faculty of Engineering and the Built Environment, 2020. http://hdl.handle.net/11427/32274.
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The performance of reinforced concrete (RC) structures, such as bridges in the heavy haul industry, may be severely impacted by fatigue when subjected to repeated cyclic loading. Fatigue not only reduces load carrying capacity and serviceability limit states (SLS), but it can cause structural failure even when the components are subjected to low stress range cyclic loading. Corrosion damage exacerbates fatigue related problems as chloride induced pitting corrosion facilitates the formation and gradual propagation of cracks under cyclic loading. A common rehabilitation and retrofitting approach that involves patch repairing and fibre reinforced polymer (FRP) strengthening has proven effective to not only restore structural capacity, but also to enhance infrastructure service life. The structural repair process involves the replacement of deteriorated cover concrete with a less permeable patch repair mortar. The patch repair only restores durability of the structure; to restore or enhance structural capacity the repair process further involves bonding of FRP laminates. Particularly in the case of FRP's with a low elastic modulus, the design is often guided by serviceability limit states as opposed to ultimate limit states (ULS), resulting in an over-reinforced structural member. In addition, the reinforcement area of commercially available FRP strengthening may exceed the design requirements, especially at low levels of corrosion damage. In both the abovementioned considerations the design may result in an over-reinforced section. At the time when this researched was proposed, the effect of increasing damage extent on fatigue behaviour of over-reinforced RC beams was not clear and merited further investigation. A scientific experimental approach was developed to investigate the long-term performance of fifteen (15) full-scale 40MPa RC beams with dimensions 155x254x2000mm and ultimate capacity of 62.3kNm. Accelerated corrosion damage was induced in varied extents which included 450mm, 800mm, 1300mm and 1800mm length to a constant degree of 10% on all specimens. Specimens from each damage extent were patch repaired using SikaCrete214 and subsequently strengthened with externally bonded with SikaCarboDurS512 carbon fibre reinforced polymer (CFRP) laminates. Four-point bending monotonic loading tests were conducted on one (1) specimen from each damage extent. The results obtained from the quasi-static tests were used to determine two (2) cyclic loading stress ranges at which the remaining 2 specimens from each damage extent would be tested under. Under the 40% and 60% stress ranges four-point bending cyclic loading tests were carried out at a test frequency of 4Hz. Information was acquired on key performance indicators that included fatigue life, crack development, failure mode and stiffness degradation, where stiffness was assessed in terms of midspan deflection, composite material strains and neutral axis shift. Information on these parameters were collected using strain gauges, linear variable differential transducers (LVDT), DEMEC strain targets and digital image correlation (DIC). Ultimate failure loads under monotonic loading showed that despite having the highest degree of corrosion, the 450mm damage extent specimen had the highest failure load of 325kN. The failure load gradually reduced to 290kN as the damage extent was increased to 1800mm and the 0mm (control) specimen failed at the lowest load of 274kN. In contrast to the static behaviour, the specimen fatigue life enhanced by 106.3% as the damage extent was increased from 450mm to 1800mm. As expected, the 40% stress range tests yielded much longer fatigue lives than their 60% stress range counterparts. Furthermore, the experimentally obtained fatigue lives were compared to three fatigue life prediction models and the Helgason and Hanson model yielded the closest correlation with the experimental results. IV ABSTRACT Crack densities were found to increase with a longer fatigue life. An increase in damage extent was found to positively affect crack development and overall stiffness of the specimen during longterm fatigue testing. This finding was further substantiated by an assessment of midspan deflection, compression concrete strain and carbon fibre strain results, which all suggested a lower neutral axis and a lower stiffness reduction rate under fatigue loading as the damage extent was increased from 450mm to 1800mm. Furthermore, the tension concrete cracks propagated gradually during longer fatigue tests periods, while the tension steel and carbon fibre were comparably less affected by the resultant internal forces. Unfortunately, the neutral axis strain measurements using DEMEC targets were unable to assess the relative effect of an increase in damage extent as well as the compression concrete and carbon fibre strains were able to. During this experimental period, it was established that the laboratory layout was not conducive for carrying out the DIC process of long-term cyclic loading tests. The area in which testing took place did not adequately protect the camera against the environment and therefore required daily storage of the equipment. Regular movement of the camera for storage purposes introduced measurement inaccuracies which accumulated over longer test periods of up 20 days. However, for the short-term tests that did not require movement of the camera, the DIC process yielded favourable results. It was possible to capture the crack patterns early in the test period when the crack growth rate and development of new cracks was high using DIC. It was found that the high strain cracks coincided with the points of maximum vertical deflection (obtained through DIC) and eventual failure location of the specimen. The points of maximum deflection obtained from the DIC process were often not at midspan, which in the absence of the DIC process, would not have been possible to predict accurately. The results have shown that the specimens with the longer damage extents exhibit improved fatigue performance than their shorter counterparts. This revealed a stark contrast to their monotonic loading performance which favoured shorter damage extents. Furthermore, DIC holds potential to predict failure location more accurately than conventional approaches used for structural health monitoring (SHS).
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El-Refaie, S. A. "Repair and strengthening of continuous reinforced concrete beams : flexural repair and strengthening of continuous reinforced concrete beams using externally bonded carbon fibre reinforced polymer." Thesis, University of Bradford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.577554.
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Ahmed, Ahmed Kamal El-Sayed. "Concrete contribution to the shear resistance of FRP-reinforced concrete beams." Thèse, [S.l. : s.n.], 2006. http://savoirs.usherbrooke.ca/handle/11143/1784.
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