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1
Kadhom, Bessam. "Blast Performance of Reinforced Concrete Columns Protected by FRP Laminates." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34752.
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Recent terrorist attacks on critical infrastructures using car bombs have heightened awareness on the needs for blast resistance of structures. Blast design of civilian buildings has not been a common practice in structural design. For this reason, there is now an urgent need to mitigate the potentially devastating effects of blast shock waves on existing structures. The current research project, the results of which are reported in this dissertation, aims to expand knowledge on blast resistance of reinforced concrete building columns, while developing a technology and design procedure for protecting critical buildings columns against the damaging effects of impulsive blast loads through the use of externally applied fibre-reinforced polymer (FRP) jackets of different material architecture. The research project has a significant experimental component, with analytical verifications.
A total of thirty two reinforced concrete columns were experimentally investigated under the effects of simulated blast loads using the University of Ottawa Shock Tube. Column dimensions were 150 mm x 150 mm in cross section and 2438 mm in length. Each concrete column was reinforced longitudinally with four 10M rebars which were tied laterally with 6.3 mm closed steel hoops, spaced at 37.5 mm and 100 mm c/c, representing seismic and non-seismic column details, respectively. The experimental research had two phases. Phase-I (sub-study) included blast tests of eight as-built, seismically detailed columns. The behaviour of these columns was explored under single and multiple blast shots, with and without the application of pre-blast axial loads. Phase-II (main-study) included column tests of different carbon FRP (CFRP) designs to investigate the significance of the use of different CFRP column jacket designs on dynamic response of twenty four seismic and non-seismic RC columns.
Analytical investigation was conducted to assess and verify the significance of experimentally investigated parameters on column response. These included the use of Single-Degree-of-Freedom (SDOF) dynamic inelastic analysis, generation of dynamic resistance functions, the effects of variable axial loads, different plastic hinge lengths and the influence of secondary moments (P- moments) on column behaviour.
The results indicate that the loading history has effects on column response, with multiple shots reducing column stiffness, and affecting dynamic response of columns relative to single blast shots of equivalent magnitude. The effect of concrete strength within the normal-strength concrete range is to increase strength and decrease deformations. Columns with CFRP jackets have considerable improvements in column deformability, with additional increases in column strength. The CFRP laminate design influences performance, with jackets having fibres in ±45o orientation especially improving column ductility and increasing plastic hinge lengths, thereby permitting redistribution of stresses and dissipating blast energy. Axial gravity loads vary during blast loads and can affect column strength. It was shown that SDOF dynamic inelastic analysis does capture key structural performance parameters in blast analysis. The consideration of experimentally observed parameters in column analysis; including the influence of CFRP design and associated change in plastic hinge length, variable axial load during response, and secondary moment (P- moments) result in significant improvements in the accuracy of blast analysis. The experimental results and the suggested improvements to the SDOF analysis technique can be used to implement a performance-based design approach recommended as part of the current research project for design of CFRP protection systems for concrete columns.This research project was conducted jointly by the National Research Council Canada (NRC) and the University of Ottawa.
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Wood, Brian Henry. "Experimental validation of an integrated FRP and visco-elastic hardening, damping, and wave-modulating system for blast resistance enhancement of RC columns." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Wood_09007dcc80538e4c.pdf.
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Thesis (M.S.)--Missouri University of Science and Technology, 2008.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed August 28, 2008) Includes bibliographical references (p. 112-115).
3
Chen, Mantai, and 陈满泰. "Combined effects of strain gradient and concrete strength on flexural strength and ductility design of RC beams and columns." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206429.
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The stress-strain relationship of concrete in flexure is one of the essential parameters in assessing the flexural strength and ductility of reinforced concrete (RC) structures. An overview of previous research studies revealed that the presence of strain gradient would affect the maximum concrete stress and respective strain developed in flexure. Previously, researchers have conducted experimental studies to investigate and quantify the strain gradient effect on maximum concrete stress and respective strain by developing two strain-gradient-dependent factors k3 and ko for modifying the flexural concrete stress-strain curve.
In this study, the author established a new analytical concrete constitutive model to describe the stress-strain behavior of both normal-and high-strength concrete in flexure with the effect of strain gradient considered. Based on this, comprehensive parametric studies have been conducted to investigate the combined effects of strain gradient and concrete strength on flexural strength and ductility design of RC beams and columns with concrete strength up to 100 MP a by employing the strain-gradient-dependent concrete stress-strain curve using non-linear moment-curvature analysis.
From the results of the parametric studies, it is evident that both the flexural strength and ductility of RC beams and columns are improved under strain gradient effect. A design value of ultimate concrete strain of 0.0032and anew equivalent rectangular concrete stress block incorporating the combined effects of strain gradient and concrete strength have been proposed and validated by comparing the proposed theoretical strength with the strength of 198 RC beams and 275 RC columns measured experimentally by other researchers. It is apparent from the comparison that the proposed equations can predict more accurately the flexural strength of RC beams and columns than the current RC design codes.
Lastly, for practical engineering design purpose, design formulas and charts have been produced for flexural strength and ductility design of RC beams and columns incorporating the combined effects of strain gradient and concrete strength.published_or_final_version
Civil Engineering
Master
Master of Philosophy
4
Peng, Jun, and 彭军. "Strain gradient effects on flexural strength and ductility design of normal-strength RC beams and columns." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48329630.
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The stress-strain characteristics of concrete developed in flexure is very important for flexural strength design of reinforced concrete (RC) members. In current RC design codes, the stress-strain curve of concrete developed in flexure is obtained by scaling down the uni-axial stress-strain curve to account for the strain gradient effect. Therefore, the maximum concrete stress that can be developed under flexure is smaller than its uni-axial strength, and the use of which always underestimates the flexural strength of RC beams and columns even though the safety factors for materials are taken as unity. Furthermore, the value of strength underestimation was different for RC beams and columns, which indicates that the extent of strain gradient will affect the maximum concrete stress and stress-strain curve developed under flexure.
To investigate the maximum concrete stress, 29 column specimens were fabricated and tested in this study. They were divided into 9 groups, each of which was poured from the same batch of concrete and contained specimens with identical cross-section properties. In each group, one specimen was tested under concentric load while the rest was/were subjected to eccentric or horizontal load. To study the strain gradient effects, the ratio of the maximum concrete compressive stress developed in the eccentrically/horizontally loaded specimens to the maximum uni-axial compressive stress developed in the counterpart concentrically loaded specimens, denoted by k3, is determined based on axial force and moment equilibriums. Subsequently, the concrete stress block parameters and the equivalent rectangular concrete stress block parameters are determined. It is found that the ratios of the maximum and equivalent concrete stress to uni-axial cylinder strength, denoted respectively by k3 and , depend significantly on strain gradient, while that of the depth of stress block to neutral axis depth, denoted by , remains relatively constant with strain gradient. Design equations are proposed to relate and with strain gradient for strength calculation, whose applicability is verified by comparing the strengths of RC beams and columns tested by various researchers with their theoretical strengths predicted by the proposed parameters and those evaluated based on provisions of RC codes.
Based on the test results, the stress-strain curve of normal-strength concrete (NSC) developed under strain gradient is derived using least-square method by minimising the errors between the theoretical axial load and moment and the respective measured values. Two formulas are developed to derive the flexural stress-strain curve, whose applicability is verified by comparing the predicted strength with those measured by other researchers.
Lastly, the application of the proposed stress-block parameters and stress-strain curve of NSC will be illustrated by developing some charts for flexural strength design of NSC beams and columns. The application will further be extended to develop strength-ductility charts for NSC beams and columns, which enable simultaneous design of strength and ductility. By adopting the proposed design charts, the flexural strength design, as well as that of the plastic hinge forming mechanism during extreme events, will be more accurate. The resulting design will be safer, more environmentally friendly and cost effective.published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
5
Bowers, Jeremy Thomas. "Nonlinear Cyclic Truss Model for Beam-Column Joints of Non-ductile RC Frames." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50437.
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Reinforced concrete (RC) moment frames comprise a significant portion of the built environment in areas with seismic hazards. The beam-to-column joints of these frames are key components that have a significant impact on the structure's behavior. Modern detailing provides sufficient strength within these joints to transfer the forces between the beams and the columns during a seismic event, but existing structures built with poor detailing are still quite prevalent. Identifying the need and extent of retrofits to ensure public safety through nondestructive means is of primary importance. Existing models used to analyze the performance of RC beam-to-column joints have either been developed for modern, well-detailed joints or are simplified so that they do not capture a broad range of phenomena.
The present study is aimed to extend a modeling technique based on the nonlinear truss analogy to the analysis of RC beam-to-column joints under cyclic loads. Steel and concrete elements were arranged into a lattice truss structure with zero-length bond-slip springs connecting them. A new steel model was implemented to more accurately capture the constitutive behavior of reinforcing bars. The joint modeling approach captured well the shear response of the joint. It also provided a good indication of the distribution of forces within the joint.
The model was validated against three recently tested beam-column subassemblies. These tests represented the detailing practice of poorly-detailed RC moment frames. The analytical results were in good agreement with the experimental data in terms of initial stiffness, strength and damage pattern through the joint.Master of Science
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Kam, Weng Yuen. "Selective Weakening and Post-Tensioning for the Seismic Retrofit of Non-Ductile RC Frames." Thesis, University of Canterbury. Department of Civil and Natural Resources Engineering, 2010. http://hdl.handle.net/10092/5237.
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This research introduces and develops a counter-intuitive seismic retrofit strategy, referred to as “Selective Weakening” (SW), for pre-1970s reinforced concrete (RC) frames with a particular emphasis on the upgrading of exterior beam-column joints. By focusing on increasing the displacement and ductility capacities of the beam-column joints, simple retrofit interventions such as selective weakening of the beam and external post-tensioning of the joint can change the local inelastic mechanism and result in improved global lateral and energy dissipation capacities.
The thesis first presents an extensive review of the seismic vulnerability and assessment of pre-1970s RC frames. Following a review of the concepts of performance-based seismic retrofit and existing seismic retrofit solutions, a thorough conceptual development of the SW retrofit strategy and techniques is presented. A “local-to-global” design procedure for the design of SW retrofit is proposed. Based on the evaluation of the hierarchy of strength at a subassembly level, a capacity-design retrofit outcome can be achieved using various combinations of levels of beam-weakening and joint post-tensioning. Analytical tools for the assessment and design of the SW-retrofitted beam-column joints are developed and compared with the test results.
Nine 2/3-scaled exterior joint subassemblies were tested under quasi-static cyclic loading to demonstrate the feasibility and effectiveness of SW retrofit for non-ductile unreinforced beam-column connections. Parameters considered in the tests included the presence of column lap-splice, slab and transverse beams, levels of post-tensioning forces and location of beam weakening. Extensive instrumentation and a rigorous testing regime allowed for a detailed experimental insight into the seismic behaviour of these as-built and retrofitted joints. Experimental-analytical comparisons highlighted some limitations of existing seismic assessment procedures and helped in developing and validating the SW retrofit design expressions. Interesting insights into the bond behaviour of the plain-round bars, joint shear cracking and post-tensioned joints were made based on the experimental results.
To complement the experimental investigation, refined fracture-mechanic finite-element (FE) modelling of the beam-column joint subassemblies and non-linear dynamic time-history analyses of RC frames were carried out. Both the experimental and numerical results have shown the potential of SW retrofit to be a simple and structurally efficient structural rehabilitation strategy for non-ductile RC frames.
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Khalil, Nariman Jaber. "Slender reinforced concrete columns." Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305374.
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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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Lillistone, Duncan. "Non-ferrous compositely reinforced concrete columns." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364791.
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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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Bhola, Rajendra Kumar. "Reliability of slender reinforced concrete columns." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25079.
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The effects of the variability in strength and loading on the reliability of slender, reinforced concrete columns are investigated using the Monte Carlo simulation technique. The columns are considered to be axially loaded with equal end eccentricities and no lateral load.
Variabilities in strength, axial load and eccentricity of axial loads are considered. A new procedure called the Implicit Uncorrelation Procedure has been developed to find the values of the failure function from the values of the basic variables named above.
The allowable axial load at various eccentricity levels corresponding to a probability of failure of one in one hundred thousand has been found for three different cross sections. Seven different slenderness ratios are considered for each cross section. The results are compared with those obtained by following the code procedures outlined in CAN3-A23.3-M77 and CSA-A23.3 (1984).
A change in the performance factor for moment magnification, ⌀m , (as given in CSA-A23.3 (1984)) is recommended in order to obtain a more accurate and consistent level of reliability in the design of slender reinforced concrete columns.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Lloyd, Alan Eric Walker. "Blast Retrofit of Reinforced Concrete Columns." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32389.
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Explosives place large demands on the lateral load carrying capacity of structures. If these loads are applied on columns, the high pressure transient loads from explosives can result in significant damage to the primary gravity load carrying elements. The loss of these elements, which are responsible from overall strength and stability of the structure, may cause collapse of all or parts of the structure. Therefore, it is important to mitigate the blast loads effects on columns. A comprehensive research study into the design, application, and use of different retrofit systems to mitigate damage to columns under blast loads has been undertaken. This research program, consisting of experimental testing and analytical investigation, sought out retrofits that address the strength of columns as well as those that enhance ductility are explored. Different materials and resistance mechanisms are used to increase column capacity. An experimental testing program was conducted using a shock tube to test the capacity of columns under blast loads. For this program, a total of sixteen reinforced concrete columns were constructed and the data from a further two columns from a previous study was compiled. Of these columns, a total of thirteen were retrofitted to mitigate the effects of blast. Carbon fibre reinforced polymer (CFRP) was applied to eight of the columns in the form of jacketing, longitudinal reinforcement, or the combination of the two. The other retrofits included steel prestressed confinement applied to one column, steel bracing acting as compression members applied to one column, and steel bracing acting as tension members applied to three columns. The columns were tested under incrementally increasing shock tube induced shock wave loading up to failure of the specimen or capacity of the shock tube. The performance of the retrofitted columns was compared with the control columns and against other retrofits. Quantitative comparisons of displacements and strains were made along with qualitative assessments of damage. The results indicated that all the retrofits increased capacity to the column, however, certain retrofits out performed others. The best FRP retrofit technique was found to be the combination of longitudinal and transverse FRP. The prestressed steel jacketing proved to be effective at increasing ductility capacity of the column. The compression brace retrofit was found to be effective in significantly increasing capacity of the column. The tension brace retrofits had the best performance over all the retrofits including the compression brace retrofit. The experimental data was used to validate analysis techniques to model the behaviour of the specimens. This technique reduced the columns to an equivalent single-degree-of-freedom (SDOF) system for dynamic analysis purposes. The reduction to the SDOF system was achieved by computing a resistance to lateral load and lateral displacement relationship. Each retrofit was carefully considered in this analysis including the retrofit’s possible effect on material and sectional properties as well as any force resistance mechanism that the retrofit introduces. The results of the modeling and experimental program were used to develop retrofit design guidelines. These guidelines are presented in detail in this thesis.
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Choe, Lisa Y. "Shear strength of circular reinforced concrete columns." Connect to resource, 2006. http://hdl.handle.net/1811/6448.
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Thesis (Honors)--Ohio State University, 2006.Title from first page of PDF file. Document formatted into pages: contains ix, 68 p.; also includes graphics. Includes bibliographical references (p. 43-45). Available online via Ohio State University's Knowledge Bank.
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Soesianawati, M. T. "Limited ductility design of reinforced concrete columns." Thesis, University of Canterbury. Department of Civil Engineering, 1986. http://hdl.handle.net/10092/3643.
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This report describes an experimental and analytical investigation
of the strength and ductility of reinforced concrete columns.
Four columns of square cross-section were tested under axial
compression loading and cyclic lateral loading applied at mid-height which
simulated seismic loading.
The main variable investigated was the quantity of transverse
confining steel used, which ranged between 17 to 46 percent of the NZS
3101:1982 recommended quantity for ductile detailing.
The experimental results are reported in the form of lateral loaddisplacement
and lateral load-curvatures hysteresis loops, curvature
profiles, transverse steel strain distributions and concrete compressive
strains.
The results are discussed and compared with the analytical predictions.
A modified equation for the quantity of confining reinforcement in
rectangular columns is recommended. Conclusions are made regarding the
ductility available from columns containing substantially less transverse
confining reinforcement than recommended by the New Zealand concrete
design code.
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Rodrigues, Hugo Filipe Pinheiro. "Biaxial seismic behaviour of reinforced concrete columns." Doctoral thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/8772.
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Doutoramento em Engenharia CivilA análise dos efeitos dos sismos mostra que a investigação em engenharia sísmica deve dar especial atenção à avaliação da vulnerabilidade das construções existentes, frequentemente desprovidas de adequada resistência sísmica tal como acontece em edifícios de betão armado (BA) de muitas cidades em países do sul da Europa, entre os quais Portugal. Sendo os pilares elementos estruturais fundamentais na resistência sísmica dos edifícios, deve ser dada especial atenção à sua resposta sob ações cíclicas. Acresce que o sismo é um tipo de ação cujos efeitos nos edifícios exige a consideração de duas componentes horizontais, o que tem exigências mais severas nos pilares comparativamente à ação unidirecional. Assim, esta tese centra-se na avaliação da resposta estrutural de pilares de betão armado sujeitos a ações cíclicas horizontais biaxiais, em três linhas principais. Em primeiro lugar desenvolveu-se uma campanha de ensaios para o estudo do comportamento cíclico uniaxial e biaxial de pilares de betão armado com esforço axial constante. Para tal foram construídas quatro séries de pilares retangulares de betão armado (24 no total) com diferentes características geométricas e quantidades de armadura longitudinal, tendo os pilares sido ensaiados para diferentes histórias de carga. Os resultados experimentais obtidos são analisados e discutidos dando particular atenção à evolução do dano, à degradação de rigidez e resistência com o aumento das exigências de deformação, à energia dissipada, ao amortecimento viscoso equivalente; por fim é proposto um índice de dano para pilares solicitados biaxialmente. De seguida foram aplicadas diferentes estratégias de modelação não-linear para a representação do comportamento biaxial dos pilares ensaiados, considerando não-linearidade distribuída ao longo dos elementos ou concentrada nas extremidades dos mesmos. Os resultados obtidos com as várias estratégias de modelação demonstraram representar adequadamente a resposta em termos das curvas envolventes força-deslocamento, mas foram encontradas algumas dificuldades na representação da degradação de resistência e na evolução da energia dissipada. Por fim, é proposto um modelo global para a representação do comportamento não-linear em flexão de elementos de betão armado sujeitos a ações biaxiais cíclicas. Este modelo tem por base um modelo uniaxial conhecido, combinado com uma função de interação desenvolvida com base no modelo de Bouc- Wen. Esta função de interação foi calibrada com recurso a técnicas de otimização e usando resultados de uma série de análises numéricas com um modelo refinado. É ainda demonstrada a capacidade do modelo simplificado em reproduzir os resultados experimentais de ensaios biaxiais de pilares.
Recent earthquakes around the world have shown that earthquake engineering research should focus on the vulnerability assessment of existing constructions. Quite often these constructions are lacking adequate seismic resistance as in the case of several reinforced concrete buildings. Since the columns are key structural elements for the adequate seismic performance of buildings, special attention should be given to their structural response under load reversals. Moreover, earthquake effects generally require the inclusion of two horizontal component loads that are recognized to be more damaging than one-direction actions. The present thesis focuses on the assessment of the structural response of RC columns under bidirectional horizontal loads in three main streamlines. First, an experimental testing campaign was performed on 24 rectangular building columns, for different types of loading. Two specimens of each column cross-section type were uniaxially tested, one in each direction (strong and weak). All the other specimens were tested under bidirectional loading conditions for different paths. All columns were tested under constant axial loading conditions. The experimental results are presented and the global behaviour of the tested columns is discussed, particularly focusing on the damage evolution, stiffness and strength degradation associated to the increasing demands, energy dissipation and equivalent viscous damping. In this framework, one proposal is introduced for a biaxial damage index and validated against the experimental results. Subsequently, the tested columns were simulated with different non-linear modelling strategies. The studied models are classified into two categories, according to the non-linearity distribution assumed in the elements: lumpedplasticity and distributed inelasticity. The analyses show that the global envelope response is satisfactorily represented with different modelling strategies, but significant differences were found in terms of strength degradation for higher drift demands and of energy dissipation. Finally, a simplified hysteretic model is proposed for the representation of the non-linear response of reinforced concrete members subjected to biaxial bending combined with constant axial load. The proposed model corresponds to an upgrade of an existing uniaxial hysteretic model, with piecewise linear behaviour, and adopts an interaction function based on the formulation of Bouc-Wen smooth hysteretic model. The proposed biaxial model requires the same type of information as for the corresponding uniaxial one, along with a correcting term given by an interaction function which modifies the response in each uniaxial direction in order to couple the two directions’ responses. For the calibration of the proposed interaction function, optimization techniques were used in order to adjust the required parameters. The validity of the simplified model is demonstrated through the simulation of the response of reinforced concrete columns tested under biaxial loading.
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YUAN, WENQING. "SLENDERNESS EFFECTS IN FRP-REINFORCED CONCRETE COLUMNS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin988054670.
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Trezona, James Richard. "Analysis and design of circular reinforced concrete columns and concrete filled steel tube columns /." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09ENS/09enst818.pdf.
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Welp, Katherine Marie 1958. "Effective stiffness of rectangular concrete columns." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276822.
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This thesis is based upon a need to re-examine the assumptions and expand upon the results arrived at in recent studies on the flexural stiffness of reinforced concrete columns. A survey is presented of concrete column design over the last 200 years. Elastic and plastic behavior of concrete columns is discussed with respect to stiffness and Euler's buckling load. Some limitations and applications of buckling load are considered. Various current code approximations of stiffness are presented. Four possible methods for computing a more exact stiffness (EI) and their advantages and disadvantages are discussed. The formula EI = M/φ provides the best solution. The two dimensional program RECTCOL which is based on the P-M-φ relationships is developed and explained. Then RECTCOL is used to show how the column flexural stiffness varies with axial load, reinforcement ratio, yield strength of the reinforcing steel, concrete strength, cover, and column dimensions. A flow chart and source code are included by RECTCOL.
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Berry, Michael Patrick. "Performance modeling strategies for modern reinforced concrete bridge columns /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/10117.
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Chin, Helen Hau Ling. "Bending displacement capacity of elongated reinforced concrete columns." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43491.
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The bending displacement capacity of elongated wall-like gravity-load columns subjected to lateral displacements due to earthquake demands on a high-rise building is of considerable concern. The long cross-sectional dimension makes these members much less flexible compared to square columns. Elongated gravity-load columns are popular because they can be hidden in walls and because they reduce the span of floor slabs, which means the thickness of the floor slabs can be reduced. No previous tests have been done on elongated gravity-load columns subjected to simulated earthquake loading. In the current study, five half-scale specimens including four column specimens and one wall specimen were subjected to constant axial compression and reverse cyclic lateral load to determine the displacement capacity of the members. The cross-sectional width-to-length ratios of the four columns were 1:1 (square), 1:2, 1:4, 1:8 and the wall specimen was 1:8. The load-deformation responses of the specimens were predicted using two nonlinear programs Response2000 and VecTor2, as well as hand calculation procedures. The predictions were used to design the test setup and were compared with the test results in order to better understand the significance of the test results. The predicted load capacities of all specimens were found to be similar to the observed maximum loads; but the displacement capacities of all specimens were significantly higher than predicted. Slip of the vertical reinforcing bars from the column foundations contributed to a large part of the increased displacement capacity of the columns. Only the elongated columns with a cross-sectional width-to-length ratios of 1:4 and 1:8 and the wall specimen suffered complete collapse during the test.
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Machado, Rafael Ignacio. "Experimental investigation of steel tubed reinforced concrete columns." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19457.
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Tapan, Mucip. "Strength evaluation of deteriorated reinforced concrete bridge columns." Related electronic resource:, 2007. http://proquest.umi.com/pqdweb?did=1407689451&sid=1&Fmt=2&clientId=3739&RQT=309&VName=PQD.
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Spuś, Piotr. "Cost analysis of reinforced concrete slabs and columns." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11454.
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Mestrado em Engenharia CivilThe construction industry is increasingly looking for solutions that are both simple and effective and that provide cost savings, speed and flexibility of execution. Two-way slabs are a form of construction unique to reinforced concrete comparing with the other major structural materials. It is an efficient, economical, and widely used structural system. The present dissertation aims to analyze and compare costs between four types of slabs: waffle slab with recuperate molds, flat slabs with drop panels, two-way slabs with beams and flat plates. In this analysis the loads considered for the floors were of a residential type. The most common spans for slabs were considered. For the analysis of the slabs the simplified methods were used. For the design, security checks and construction rules, it was considered the current legislation applied in the member countries of the European Committee for Standardization, namely the Eurocodes. In order to compare the cost of usage of these four types of floor systems, in the analysis of the results it is shown the price for the necessary resources and the total cost of each slab for each study model per m2 of total area of a building. From this dissertation, the conclusion may be drawn that waffle slabs have a lower cost than flat slabs with enlarged column heads for all spans considered and respectively flat plates have a lower cost than slabs with beams. From all of the slabs, waffle slab is the most economical one in the range of considered spans.
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Mohammed, Mohammed Gaber Elshamandy. "GFRP-reinforced concrete columns under simulated seismic loading." Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/10242.
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Abstract : Steel and fiber-reinforced-polymer (FRP) materials have different mechanical and physical characteristics. High corrosion resistance, high strength to weight ratio, non-conductivity, favorable fatigue enable the FRP to be considered as alternative reinforcement for structures in harsh environment. Meanwhile, FRP bars have low modulus of elasticity and linear-elastic stress-strain curve. These features raise concerns about the applicability of using such materials as reinforcement for structures prone to earthquakes. The main demand for the structural members in structures subjected to seismic loads is dissipating energy without strength loss which is known as ductility. In the rigid frames, columns are expected to be the primary elements of energy dissipation in structures subjected to seismic loads.
The present study addresses the feasibility of reinforced-concrete columns totally reinforced with glass-fiber-reinforced-polymer (GFRP) bars achieving reasonable strength and the drift requirements specified in various codes. Eleven full-scale reinforced concrete columns—two reinforced with steel bars (as reference specimens) and nine totally reinforced with GFRP bars—were constructed and tested to failure. The columns were tested under quasi-static reversed cyclic lateral loading and simultaneously subjected to compression axial load. The columns are 400 mm square cross-section with a shear span 1650 mm. The specimen simulates a column with 3.7 m in height in a typical building with the point of contra-flexure located at the column mid-height. The tested parameters were the longitudinal reinforcement ratio (0.63, 0.95 and 2.14), the spacing of the transverse stirrups (80, 100, 150), tie configuration (C1, C2, C3 and C4), and axial load level (20%, 30% and 40%).
The test results clearly show that properly designed and detailed GFRP-reinforced concrete columns could reach high deformation levels with no strength degradation. An acceptable level of energy dissipation compared with steel-reinforced concrete columns is provided by GFRP reinforced concrete columns. The dissipated energy of GFRP reinforced concrete columns was 75% and 70% of the counter steel columns at 2.5% and 4% drift ratio respectively. High drift capacity achieved by the columns up to 10% with no significant loss in strength. The high drift capacity and acceptable dissipated energy enable the GFRP columns to be part of the moment resisting frames in regions prone to seismic activities. The experimental ultimate drift ratios were compared with the estimated drift ratios using the confinement Equation in CSA S806-12. It was found from the comparison that the confinement Equation underestimates values of the drift ratios thus the experimental drift ratios were used to modify transverse FRP reinforcement area in CSA S806-12. The hysteretic behavior encouraged to propose a design procedure for the columns to be part of the moderate ductile and ductile moment resisting frames. The development of design guidelines, however, depends on determining the elastic and inelastic deformations and on assessing the force modification factor and equivalent plastic-hinge length for GFRP-reinforced concrete columns. The experimental results of the GFRP-reinforced columns were used to justify the design guideline, proving the accuracy of the proposed design equations.L’acier et les matériaux à base de polymères renforcés de fibres (PRF) ont des caractéristiques physiques et mécaniques différentes. La résistance à la haute corrosion, le rapport résistance vs poids, la non-conductivité et la bonne résistance à la fatigue font des barres d’armature en PRF, un renforcement alternatif aux barres d’armature en acier, pour des structures dans des environnements agressifs. Cependant, les barres d’armature en PRF ont un bas module d’élasticité et une courbe contrainte-déformation sous forme linéaire. Ces caractéristiques soulèvent des problèmes d'applicabilité quant à l’utilisation de tels matériaux comme renforcement pour des structures situées en forte zone sismique. La principale exigence pour les éléments structuraux des structures soumises à des charges sismiques est la dissipation d'énergie sans perte de résistance connue sous le nom de ductilité. Dans les structures rigides de type cadre, on s'attend à ce que les colonnes soient les premiers éléments à dissiper l'énergie dans les structures soumises à ces charges. La présente étude traite de la faisabilité des colonnes en béton armé entièrement renforcées de barres d’armature en polymères renforcés de fibres de verre (PRFV), obtenant une résistance et un déplacement latéral raisonnable par rapport aux exigences spécifiées dans divers codes. Onze colonnes à grande échelle ont été fabriquées: deux colonnes renforcées de barres d'acier (comme spécimens de référence) et neuf colonnes renforcées entièrement de barres en PRFV. Les colonnes ont été testées jusqu’à la rupture sous une charge quasi-statique latérale cyclique inversée et soumises simultanément à une charge axiale de compression. Les colonnes ont une section carrée de 400 mm avec une portée de cisaillement de 1650 mm pour simuler une colonne de 3,7 m de hauteur dans un bâtiment typique avec le point d’inflexion situé à la mi-hauteur. Les paramètres testés sont : le taux d’armature longitudinal (0,63%, 0,95% et 2,14 %), l'espacement des étriers (80mm, 100mm, 150 mm), les différentes configurations (C1, C2, C3 et C4) et le niveau de charge axiale (20%, 30 % et 40%). Les résultats des essais montrent clairement que les colonnes en béton renforcées de PRFV et bien conçues peuvent atteindre des niveaux de déformation élevés sans réduction de résistance. Un niveau acceptable de dissipation d'énergie, par rapport aux colonnes en béton armé avec de l’armature en acier, est atteint par les colonnes en béton armé de PRFV. L'énergie dissipée des colonnes en béton armé de PRFV était respectivement de 75% et 70% des colonnes en acier à un rapport déplacement latéral de 2,5% et 4%. Un déplacement supérieur a été atteint par les colonnes en PRFV jusqu'à 10% sans perte significative de résistance. La capacité d’un déplacement supérieur et l’énergie dissipée acceptable permettent aux colonnes en PRFV de participer au moment résistant dans des régions sujettes à des activités sismiques. Les rapports des déplacements expérimentaux ultimes ont été comparés avec les rapports estimés en utilisant l’Équation de confinement du code CSA S806-12. À partir de la comparaison, il a été trouvé que l’Équation de confinement sous-estime les valeurs des rapports de déplacement, donc les rapports de déplacement expérimentaux étaient utilisés pour modifier la zone de renforcement transversal du code CSA S806-12. Le comportement hystérétique encourage à proposer une procédure de conception pour que les colonnes fassent partie des cadres rigides à ductilité modérée et résistant au moment. Cependant, l'élaboration de guides de conception dépend de la détermination des déformations élastiques et inélastiques et de l'évaluation du facteur de modification de la force sismique et de la longueur de la rotule plastique pour les colonnes en béton armé renforcées de PRFV. Les résultats expérimentaux des colonnes renforcées de PRFV étudiées ont été utilisés pour justifier la ligne directrice de conception, ce qui prouve l’efficacité des équations de conception proposées.
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Simon, Rodney. "Experimental investigation of repaired reinforced concrete highway bridge columns." Master's thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-03022010-020020/.
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Gao, Bo. "FRP strengthened RC beams : taper design and theoretical analysis /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?MECH%202005%20GAO.
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Ross, Jason Donald. "Analytical models for reinforced concrete columns retrofitted with fiber-reinforced polymer composites." Connect to resource, 2007. http://hdl.handle.net/1811/25128.
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Thesis (Honors)--Ohio State University, 2007.Title from first page of PDF file. Document formatted into pages: contains 67 p.; also includes graphics. Includes bibliographical references (p. 60-62). Available online via Ohio State University's Knowledge Bank.
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Ho, Ching-ming Johnny, and 何正銘. "Inelastic design of reinforced concrete beams and limited ductilehigh-strength concrete columns." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B27500305.
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Acun, Bora. "Energy Based Seismic Performance Assessment Of Reinforced Concrete Columns." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611728/index.pdf.
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Severe seismic events in urban regions during the last two decades revealed that the structures constructed before the development of modern seismic codes are the most vulnerable to earthquakes. Sub-standard reinforced concrete buildings constitute an important part of this highly vulnerable urban building stock. There is urgent need for the development and improvement of methods for seismic performance assessment of existing reinforced concrete structures.
As an alternative to current conventional force-based assessment methods, a performance evaluation procedure for structural members, mainly reinforced concrete columns is proposed in this study, by using an energy-based approach combined with the low cycle fatigue concept. An energy-based hysteresis model is further introduced for representing the inelastic response of column members under severe seismic excitations. The shape of the hysteresis loops are controlled by the dissipated cumulative energy whereas the ultimate strength is governed by the low cycle fatigue behavior. These two basic characteristics are obtained experimentally from full scale specimens tested under constant and variable amplitude
displacement cycles.
The first phase of the experimental program presented in the study constitutes of testing sub-standard non-conforming column specimens. The second phase of testing was conducted on standard, code compliant reinforced concrete columns. A
total number of 13 specimens were tested. The behavior of these specimens was observed individually and comparatively according to the performance based objectives. The results obtained from the experiments were employed for developing relations between the energy dissipation capacity of specimens, the specimen properties as well as the imposed displacement history. Moreover, the measured rotation capacities at the plastic regions are evaluated comparatively with the limits proposed by modern displacement-based seismic design and assessment provisions.
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Imbeau, Paul. "Response of Reinforced Concrete Columns Subjected to Impact Loading." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23067.
Full textAbstract:
Reinforced Concrete (RC) bridge piers, RC columns along exterior of buildings or those located in parking garages are designed to support large compressive axial loads but are vulnerable to transverse out-of-plane loadings, such as those arising from impacts or explosions. To address a lack of understanding regarding blast and impact response of RC members and the need for retrofit techniques to address deficiencies in existing structures, a multi-disciplinary team including various institutes of the National Research Council and the University of Ottawa has initiated work towards developing a fibre reinforced polymer composite protection system for RC columns subjected to extreme shocks. This thesis will focus on the impact program of the aforementioned project. An extensive literature review was conducted to gain a better understanding of: impact loading and associated dynamic effects; experimental testing of RC members subjected to impact; experimental testing of axially loaded members; and retrofit methods for the protection of RC under impact loading. Five half-scale RC columns were constructed and tested using a drop-weight impact machine and two additional specimens were tested under static loading. Deflections, strain distributions within the columns, impact loads and reaction loads were measured during the testing of the built RC members. Comparisons of experimental datum were established between members with differing levels of axial load and between a retrofitted and a non-retrofitted member. Single-degree-of-freedom analysis was used to obtain the predicted response of certain columns under impact loading allowing for comparisons with experimental data.
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Dunwoodie, David. "Seismic retrofit of bridge columns using fibre-reinforced concrete." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0007/MQ44005.pdf.
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Zhou, Wenxing. "Reliability evaluations of reinforced concrete columns and steel frames." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58250.pdf.
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Melandinos, Athanasios. "Fire behaviour of reinforced concrete columns in real buildings." Thesis, University of Manchester, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488041.
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Kuper, Alan Benjamin. "Detection of delaminations of FRP retrofitted reinforced concrete columns." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Fall2009/a_kuper_111909.pdf.
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Thesis (M.S. in civil engineering)--Washington State University, December 2009.Title from PDF title page (viewed on Dec. 28, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 51).
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Abd, El Fattah Ahmed Mohsen. "Eccentricity based analysis of confined reinforced concrete circular columns." Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1121.
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ROSA, SYLVIA PECEGUEIRO DO AMARAL PEREIRA DA. "THEORETICAL AND EXPERIMENTAL ANALYSIS OF BAMBOO REINFORCED CONCRETE COLUMNS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2002. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=2904@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORAtualmente o mundo enfrenta uma grave crise ambiental e elevados índices de pobreza. Com a intenção de minimizar estes problemas esta Tese propõe a alternativa do uso do bambu como armadura em pilares de concreto armado, substituindo o aço em construções civis. O comportamento dos pilares de concreto armado é descrito através de uma revisão bibliográfica e de ensaios realizados em pilares curtos submetidos à carga axial, dos quais três foram armados com bambu e um com aço. Abordam-se aspectos relativos à taxa de armadura longitudinal, a resistência do bambu à compressão e a aderência entre bambu e concreto, para isto ensaios complementares em ripas pequenas de bambu sob carga de compressão centrada e testes de arrancamento utilizando o produto sikadur 32 gel para acrescentar aderência ao bambu e constatar sua eficiência, foram realizados e comparados com um corpo de prova armado com aço. Os pilares de concreto armados com bambu e aço foram comparados e analisados. Segundo recomendações das normas trabalhos futuros foram propostos.
Nowadays the world faces a serious environmental crisis and high poverty rates. Intending to minimize these problems, this thesis proposes the alternative usage of bamboo as reinforcement on columns of reinforced concrete, substituting steel in civil constructions. The reinforced concrete columns performance is described through a bibliographical revision and experiments done on short columns submited to axial load: three were built with bamboo and one with steel. Aspects related to the surcharge of longitudinal reinforcement, bamboo resistance to compression and adherence between bamboo and concrete are discussed extensively. With this purpose, subsequent experiments were made using small chips of bamboo submited to strong centered compression and also, Pull Out tests, utilizing the product Sikadur 32 gel to add adherence to bamboo and appraise its efficiency, were performed and compared to a body of proof built with steel. The concrete columns reinforced with bamboo and steel were thoroughly compared and analyzed. According to the pattern experiments, future developments on this research were proposed.
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Al-Bayti, Abdullah. "Vulnerability of Reinforced Concrete Columns to External Blast Loading." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35970.
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Reinforced concrete columns are essential elements that are responsible for overall strength and stability of structures. Loss of a column within a frame can cause progressive collapse. While some research has been conducted on blast performance of reinforced columns, primarily under far-field explosions, very limited work exists on the effects of close-in explosions. Dynamic response of concrete columns, in multi storey building, was investigated under close-in blast loads numerically, using FEM software LS-DYNA. A six-storey reinforced concrete building was selected for this purpose. Different standoff distance/charge mass combinations were used to investigate the failure modes of external building columns. Three different charge masses were used; i) backpack bomb having 22.67 kg (50 lbs) of TNT, ii) compact sedan car bomb with 227 kg (500 lbs) of TNT and iii) sedan car bomb with 454 kg (1000 lbs) of TNT. The explosives were placed at different distances relatively close to the structure, triggering different failure modes. Effects of transverse reinforcement and column location (edge versus corner column) were studied under different combinations of charge weight and standoff distance.
Column response under dynamic blast load was identified as either local or global. The results show that the failure mode with backpack bombs located at small standoff distance is either local breaching or concrete scabbing. Direct shear failure occurred at column supports when higher charge masses were detonated at close distances. As the standoff distance increased the response changed from breaching or direct shear to diagonal tension and flexure. The column transverse reinforcement played a major role in controlling diagonal shear cracks and promoting flexural response. Hence, the amount and spacing of transverse reinforcement were observed to be important design parameters.
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Zaina, Mazen Said Civil & Environmental Engineering Faculty of Engineering UNSW. "Strength and ductility of fibre reinforced high strength concrete columns." Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2005. http://handle.unsw.edu.au/1959.4/22054.
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The main structural objectives in column design are strength and ductility. For higher strength concretes these design objectives are offset by generally poor concrete ductility and early spalling of the concrete cover. When fibres are added to the concrete the post peak characteristics are enhanced, both in tension and in compression. Most of the available experimental data, on fibre reinforced concrete and fibre reinforced high strength concrete columns, suggest that an improvement in both ductility and load carrying capacity due to the inclusion of the fibres. In this thesis the ductility and strength of fibre reinforced high strength concrete are investigated to evaluate the effect of the different parameters on the performance of columns. The investigation includes both experimental and the numerical approaches with 56 high strength fibre reinforced concrete columns being tested. The concrete strength ranged between 80 and 100 MPa and the columns were reinforced with 1, 2 or 2.6 percent, by weight, of end hooked steel fibres. The effect of corrugated Polypropylene fibres on the column performance was also examined. No early spalling of the cover was observed in any of the steel fibre reinforced column tested in this study. A numerical model was developed for analysis of fibre and non-fibre reinforced eccentrically loaded columns. The column is modelled as finite layers of reinforced concrete. Two types of layers are used, one to represent the hinged zone and the second the unloading portion of the column. As the concrete in the hinged layers goes beyond the peak for the stress verus strain in the concrete the section will continue to deform leading to a localised region within a column. The numerical model is compared with the test data and generally shows good correlation. Using the developed model, the parameters that affect ductility in fibre-reinforced high strength concrete columns are investigated and evaluated. A design model relating column ductility with confining pressure is proposed that includes the effects of the longitudinal reinforcement ratio, the loading eccentricity and the fibre properties and content and design recommendations are given.
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Bournas, Dionysios A., Thanasis C. Triantafillou, and Catherine G. Papanicolaou. "Retrofit of Seismically Deficient RC Columns with Textile- Reinforced Mortar (TRM) Jackets." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244049636138-65944.
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The effectiveness of a new structural material, namely textilereinforced mortar (TRM), was investigated experimentally in this study as a means of confining old-type reinforced concrete columns with limited capacity due to bar buckling or due to bond failure at lap splice regions. Comparisons with equal stiffness and strength fiber-reinforced polymer (FRP) jackets allow for the evaluation of the effectiveness of TRM versus FRP. Tests were carried out on full scale non-seismically detailed RC columns subjected to cyclic uniaxial flexure under constant axial load. Thirteen cantilever-type specimens with either continuous longitudinal reinforcement (smooth or deformed) or lap splicing of longitudinal bars at the floor level were constructed and tested. Experimental results indicated that TRM jacketing is quite effective as a means of increasing the cyclic deformation capacity of old-type RC columns with poor detailing, by delaying bar buckling and by preventing splitting bond failures in columns with lap spliced bars. Compared with their FRP counterparts, TRM jackets used in this study were found to be equally effective in terms of increasing both the strength and deformation capacity of the retrofitted columns. From the response of specimens tested in this study, it can be concluded that TRM jacketing is an extremely promising solution for the confinement of reinforced concrete columns, including poorly detailed ones with or without lap splices in seismic regions.
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Wang, Lu, and 王璐. "Post-compressed plates for strengthening preloaded reinforced concretecolumns." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50162664.
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Reinforced concrete (RC) columns are the primary load-bearing structural components in buildings. Over time these columns may need to be repaired or strengthened either due to defective construction, having higher loads than those foreseen in the initial design of the structure, or as a result of material deterioration or accidental damage. Three external strengthening methods, namely steel jacketing, concrete jacketing and composite jacketing, are commonly adopted for upgrading the ultimate load capacity of RC columns. Among these strengthening techniques for RC columns, steel jacketing, which is easy to construct, less prone to debonding and has better fire resistance than bonded plates, has been proven to be an effective retrofitting scheme and is the most commonly used.
Different methods for strengthening existing RC columns have been proposed in the literature. However, no matter which jacket is used to strengthen RC columns, the adverse effects of pre-existing loads on stress-lagging between the concrete core and the new jacket have yet to be solved. In order to deal with this problem, a new postcompression approach was proposed for strengthening preloaded RC columns. In this approach, the slightly precambered steel plates were used. The advantages of this ‘post-compressed plates’ (PCP) strengthening technique are that both the strength and deformability of existing columns can be enhanced and the design life of old buildings can be prolonged.
Due to the aforementioned advantages, the PCP strengthening technique was investigated in this study. To begin with, axial compression tests of the PCP strengthened columns were conducted. The overall response, in particular the internal force distribution between concrete and steel plates was obtained. It was observed that the plate thickness and preloading level had dominant effects on the behaviour of PCP strengthened columns. Subsequently, eccentric compression tests of PCP strengthened columns were undertaken. The behaviour of PCP strengthened columns was mainly affected by the degree of eccentricity and plate thickness. Placing flat and precambered steel plates on the tension and compression sides respectively of the RC columns and using post-compression method on the compression side can significantly improve the ultimate load capacity of RC columns under large eccentricity; while placing precambered steel plates on the side faces of the RC columns can significantly improve the ultimate load capacity of RC columns under small eccentricity. Finally, axial compression tests of PCP repaired fire-exposed columns were carried out. The ultimate load capacity of fire-exposed columns can be restored up to 72% of original level by using this post-compression approach. The corresponding theoretical models were also developed to predict the ultimate load capacity of PCP strengthened columns. Comparison of theoretical and experimental results showed that the theoretical models accurately predicted the load-carrying capacities of PCP strengthened columns.
According to the experimental and theoretical results, a unified design procedure for the PCP strengthened columns was proposed to aid engineers in designing this new type of PCP strengthened columns and to ensure proper column detailing for desirable performance. The design procedure was validated by the available experimental and theoretical results.published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
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熊朝暉 and Zhaohui Xiong. "Reinforced concrete column behavior under cyclic loading." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31243836.
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Xiong, Zhaohui. "Reinforced concrete column behavior under cyclic loading /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23530121.
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Wu, Y. F. "Seismic retrofitting of rectangular reinforced concrete columns with partial interaction plating /." Title page, abstract and table of contents only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phw9591.pdf.
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Loedolff, Matthys Johannes. "The behaviour of reinforced concrete cantilever columns under lateral impact load." Thesis, Stellenbosch : Stellenbosch University, 1989. http://hdl.handle.net/10019.1/67104.
Full textAbstract:
Microreproduction of original thesis.Thesis (PhD)--Stellenbosch University, 1990.
Some digitised pages may appear illegible due to the condition of the original microfiche copy.
ENGLISH ABSTRACT: see item for full text
AFRIKAANSE OPSOMMING: sien item vir volteks.
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Jeyarupalingam, Nadarajah. "Steel, steel/concrete composite and reinforced concrete beams and columns exposed to fire." Thesis, City University London, 1996. http://openaccess.city.ac.uk/7766/.
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This thesis describes the development of a numerical method for the structural analysis of beams and columns subjected to a non-linear variation of temperatures in all three directions. The numerical method allows for analysis of a wide variety of cross sections with a number of materials and members with varying cross section along the length. The member can be subjected to any combination of axial load, end moments, lateral load and bi-axial bending. Any fire temperature characteristic can be specified. The numerical method has been validated by comparing results with a number of experimental results on steel, concrete and composite beams and columns from literature and with the experiments carried out under this research programme. Experiments were carried out on seven columns with non-uniform temperature distribution along the length and across the depth. The test rig was designed and manufactured at City University. Electrical heating elements were used to heat the specimens. To obtain a comprehensive temperature profile of the test columns several thermocouples were used. Deflection measurements were made using displacement transducers placed at different positions. Using the new method of analysis a simple design method for steel columns subjected to non-uniform temperature distribution across the depth of the section has been developed. The method has been validated with a number of results on H-section columns from numerical experiments performed using the computer programs developed in this thesis. Another parametric study has been carried out to improve the inherent fire resistance capacity of Slimflor beams. It is concluded that it is possible to design a Slimflor beam with higher fire resistance capacity than the current rating of 60 minutes by introducing steel reinforcing bars at appropriate place.
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Pinho, Rui. "Selective retrofitting of RC structures in seismic areas." Thesis, Imperial College London, 2000. http://hdl.handle.net/10044/1/7166.
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Lara, Otton. "The flexural seismic resistant design of reinforced concrete bridge columns." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/39532.
Full textAbstract:
Experimental studies about the cyclic response of reinforced concrete bridge columns designed
to avoid shear failure and subjected to cyclic, reversible, and increasing displacements have been
performed in several laboratories around the world. As a consequence there are several force-displacement relationships, called resultant models, that allow to predict the response of those
columns. However, the use of the resultant models for earthquake response requires extensive
calibration of several parameters.
In this investigation a Finite Fiber Element Model, FFEM, is obtained after calibrating first, the
response of 30 circular reinforced concrete bridge columns tested under cyclic, reversible, and
increasing displacements. Then a re-calibration is carried out in order to simulate the response of
two additional columns shake table tested under two earthquake ground motions. After obtaining
satisfactory results the FFEM was used to simulate the seismic response of three bridge columns
designed according to the prescriptions of the new seismic design bridge code.
The FFEM is able to predict directly four flexural failure mechanisms: cracking and crushing of
the unconfined and confined concrete, fracture of the longitudinal steel bars due to tension, P-Δ
effects, and fatigue of the longitudinal steel bars. Indirectly, the FFEM is able to predict the
possible buckling of the longitudinal bars by capturing the confined concrete strain time-history.
In order to capture the low-cyclic fatigue, the FFEM through inelastic dynamic analysis is able to
calculate the number of cycles and the amplitude of the cyclic plastic strains so these quantities
are introduced into the fatigue equation. The fracture of the bars due to low-cyclic fatigue is a
failure mechanism that depends on the accumulation of damage along the severe ground motion.
The way to estimate the loss of fatigue life in a steel bar is considering the effect of the duration
in the calculations since the materials stress-strain relationships are independent of the duration
of the ground motion.
In order to determine the accumulation of damage in the bridge column a Cyclic Damage Index
is proposed here. The Index is based on the energy dissipated by the column at the end of the
ground motion.
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Ferrell, Monica Joy. "Flexural Behavior of Carbon/Epoxy IsoTruss Reinforced-Concrete Beam-Columns." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd695.pdf.
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Yalçin, Cem. "Seismic evaluation and retrofit of existing reinforced concrete bridge columns." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0020/NQ46554.pdf.
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Zahn, Franz August. "Design of reinforced concrete bridge columns for strength and ductility." Thesis, University of Canterbury. Department of Civil Engineering, 1985. http://hdl.handle.net/10092/2872.
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Methods for the design of reinforced concrete bridge columns and
piers for strength and ductility are considered. The investigations cover
the following areas.
An experimental investigation of the influence of reinforcing steel
grade and amount of confining steel on the stress-strain behaviour of
confined concrete is presented. The results are discussed and compared
with theoretical models. Special attention is given to the possibility
of fracture of the confining steel.
An extensive experimental investigation into the ductile performance
of a range of reinforced concrete columns is presented. The columns were
subjected to constant axial load and cyclic lateral displacements. The
test units included four square columns with the lateral load applied
in the direction of a cross section diagonal, six circular hollow columns
with different wall thickness to diameter ratios, and four columns with
transverse reinforcement from Grade 380 steel. The available strength and
ductility of the columns is discussed and compared with the performance
of columns tested previously at the University of Canterbury, and with
theoretical predictions using monotonic as well as cyclic moment-curvature
analyses. The main variables for the solid columns were the influence of
biaxial bending, the use of Grade 380 transverse steel for confinement,
and the spacing between transverse bars along the column axis. The
circular hollow columns were unconfined on the inside face of the tube
wall, and the main variables were the influence of the axial load level
and the wall thickness.
The implications of the column test results, including the results
of other investigations, for the design of reinforced concrete columns
for strength and ductility are discussed and, where appropriate, used to
calibrate theoretical models. In particular, the influence of cyclic
loading on the strength deterioration of reinforced concrete columns with
high axial loads is emphasized. More realistic definitions of the ideal
flexural strength, of the flexural overstrength and of the yield curvature
are suggested and, together with a set of criteria for the ultimate limit
state, used to establish design charts for the available strength and
ductility of reinforced concrete columns. A cyclic moment-curvature
analysis was used for this purpose, incorporating cyclic stress-strain
models for the concrete and for the steel, thus taking into account the
cyclic strength deterioration observed for columns with high axial loads.
Finally, a rational step-by-step design procedure is presented that
will make less complex the task of considering the great number of
variables involved in the seismic design of reinforced concrete columns
for both strength and ductility.