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1
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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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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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.<br>Applied Science, Faculty of<br>Civil Engineering, Department of<br>Graduate
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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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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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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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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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Bugaldian, Adel Abdulmoula. "Concrete columns confined with scrap tires." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0022/MQ52289.pdf.
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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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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.<br>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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Xue, Hongyu. "Structural behaviour of high strength concrete columns." Thesis, University of Westminster, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339246.
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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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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 Civil<br>A 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.<br>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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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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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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Abd, El Fattah Ahmed Mohsen. "Behavior of concrete columns under various confinement effects." Diss., Kansas State University, 2012. http://hdl.handle.net/2097/13533.
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Doctor of Philosophy<br>Department of Civil Engineering<br>Hayder Rasheed<br>The analysis of concrete columns using unconfined concrete models is a well established practice. On the other hand, prediction of the actual ultimate capacity of confined concrete columns requires specialized nonlinear analysis. Modern codes and standards are introducing the need to perform extreme event analysis. There has been a number of studies that focused on the analysis and testing of concentric columns or cylinders. This case has the highest confinement utilization since the entire section is under confined compression. On the other hand, the augmentation of compressive strength and ductility due to full axial confinement is not applicable to pure bending and combined bending and axial load cases simply because the area of effective confined concrete in compression is reduced. The higher eccentricity causes smaller confined concrete region in compression yielding smaller increase in strength and ductility of concrete. Accordingly, the ultimate confined strength is gradually reduced from the fully confined value fcc (at zero eccentricity) to the unconfined value f’c (at infinite eccentricity) as a function of the compression area to total area ratio. The higher the eccentricity the smaller the confined concrete compression zone. This paradigm is used to implement adaptive eccentric model utilizing the well known Mander Model and Lam and Teng Model.
Generalization of the moment of area approach is utilized based on proportional loading, finite layer procedure and the secant stiffness approach, in an iterative incremental numerical model to achieve equilibrium points of P- and M- response up to failure. This numerical analysis is adaptod to asses the confining effect in circular cross sectional columns confined with FRP and conventional lateral steel together; concrete filled steel tube (CFST) circular columns and rectangular columns confined with conventional lateral steel. This model is validated against experimental data found in literature. The comparison shows good correlation. Finally computer software is developed based on the non-linear numerical analysis. The software is equipped with an elegant graphics interface that assimilates input data, detail drawings, capacity diagrams and demand point mapping in a single sheet. Options for preliminary design, section and reinforcement selection are seamlessly integrated as well. The software generates 2D interaction diagrams for circular columns, 3D failure surface for rectangular columns and allows the user to determine the 2D interaction diagrams for any angle between the x-axis and the resultant moment. Improvements to KDOT Bridge Design Manual using this software with reference to AASHTO LRFD are made. This study is limited to stub columns.
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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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Razvi, Salim R. "Confinement of normal and high-strength concrete columns." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/10075.
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A comprehensive research project was conducted to investigate the behaviour and design of earthquake resistant normal-strength and high-strength concrete columns. The project included three essential components; testing of full size columns, development of an analytical model, and development of a design procedure. The experimental program consisted of material research and structural testing. The first phase was designed to study mechanical properties of high-strength concrete, which involved testing of a large number of concrete cylinders. The second phase was designed to investigate performance of confined normal and high-strength concrete columns under concentric compression. The experimental program included tests of 46 full size square and circular columns, with concrete strength ranging between 60 MPa and 124 MPa. The parameters considered included; cross-sectional shape (circular and square), volumetric ratio and spacing of transverse reinforcement, distribution of longitudinal reinforcement and resulting tie arrangement, yield strength of transverse reinforcement, concrete compressive strength, influence of longitudinal reinforcement in circular columns, and type of circular reinforcement (continuous spiral and circular hoops). The analytical component of the research program involved development of a mathematical model to represent stress-strain relationship of confined concrete. This was done in two steps. The first step included formulation of the relationship for normal strength concrete, for which extensive test data was available. The second step involved modification of the model for high-strength concrete. An extensive literature survey was first conducted, followed by evaluation of previous test data. This information was used, along with the results of the experimental phase of this investigation to develop a generalized cofinement model for normal-strength and high-strength concrete columns. The analytical and experimental research was used in developing a design procedure for confinement of earthquake resistant concrete columns. The procedure includes all the relevant parameters of confinement that have been observed to be important in column tests, and relates the design variables to deformation capacities. A displacement based design methodology was developed, where the lateral drift demand is a design parameter. This approach leads to different confinement steel requirements for columns with different deformability demands, an approach currently lacking in practice. Furthermore, the reinforcement arrangement is recognized as a design parameter, allowing lower volumetric ratio of confinement reinforcement for efficient arrangements. This may result in significant savings in steel, eliminating the common problem of steel congestion in earthquake resistant columns. (Abstract shortened by UMI.)
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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.<br>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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Becque, Jurgen. "Analytical modeling of concrete columns confined by FRP." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0025/MQ51686.pdf.
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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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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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Aho, Mark Francis. "A database for encased and concrete-filled columns." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/19061.
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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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Sabri, Amirreza. "Seismic Retrofit of Concrete Columns by Transverse Prestressing." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/26079.
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Performance of buildings and bridges during past earthquakes has indicated that many of these structures are vulnerable to seismic damage and structural collapse. The deficiencies in pre-1970s design codes have resulted in poor performance of reinforced concrete structures during seismic excitations. The Richter Magnitude 6.6 - 1971 San Fernando Earthquake raised awareness for seismic retrofit needs of existing buildings for the first time. The majority of deficiencies of vulnerable concrete columns can be overcome through seismic retrofits that involve additional transverse reinforcement. This can be done either by providing reinforced concrete, steel, or fibre-reinforced polymer (FRP) jackets around existing columns; or by applying transverse prestressing to columns (RetroBelt System).
The research project presented in this thesis involves a seismic retrofit methodology for seismically deficient building and bridge columns, utilizing the use of high-strength packaging straps as external reinforcement for transverse prestressing. The emphasis in the project is placed on experimental research. Three seismically deficient full-size reinforced concrete columns, with a circular, a square and a rectangular cross- section, either critical in shear or flexure, were designed, built and tested under simulated seismic loading. The results indicate that external prestressing of columns in transverse direction with high-strength steel straps improves ductility and energy dissipation capacity of seismically deficient columns. They further indicate that current analytical techniques can be used to predict the force-displacement relationships of columns. A design approach is presented for the retrofit methodology investigated.
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Friis, Jesper. "Structural performance of confined high strength concrete columns." Thesis, City University London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397864.
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BUFFONI, SALETE SOUZA DE OLIVEIRA. "BUCKLING ANALYSIS OF LONGITUDINAL REINFORCEMENT IN CONCRETE COLUMNS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5517@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>A flambagem das armaduras longitudinais em pilares de
concreto armado
pode ocorrer na região entre dois estribos consecutivos, ou
pode envolver um
certo número de estribos. As normas de projeto existentes
não fornecem uma
metodologia apropriada para o dimensionamento dos estribos
em diferentes
situações. O presente trabalho tem por objetivo desenvolver
uma formulação que
permita analisar a flambagem das armaduras longitudinais em
pilares de concreto
armado submetidos a carregamento axial levando em conta o
espaçamento entre
os estribos, o diâmetro e arranjo dos estribos na seção
transversal e o diâmetro das
armaduras longitudinais. Para este propósito um método
analítico para a avaliação
da flambagem da armadura longitudinal é proposto,
considerando-se as barras
longitudinais restringidas pela rigidez axial ou à flexão
dos estribos. Admite-se
que a armadura longitudinal funciona como uma coluna
esbelta. Consideram-se
duas formas de modelagem da atuação dos estribos: como
apoios elásticos
discretos e como base elástica contínua. O presente
trabalho trata a coluna com
um ou mais modos de deformação, incluindo certas não-
linearidades. São
fornecidos cargas críticas e caminhos pós-críticos para
tais casos. Como resultado
deste estudo, apresenta-se uma proposta para
dimensionamento racional dos
estribos que permite estudar diferentes alternativas em um
ábaco de utilização
simples para projeto. Apresentam-se comparações com
resultados experimentais
da literatura em pilares de concreto armado. Isto permite
uma avaliação crítica dos
desenvolvimentos teóricos realizados e da forma proposta de
dimensionamento
racional dos estribos.<br>Buckling of longitudinal reinforcement in reinforced
concrete columns may
occur in the region between two consecutive ties, or may
involve a number of ties.
The existing design code specifications do not provide an
appropriate
methodology for the design of the transversal reinforcement
in different situations.
The main objective of the present work is to develop a
formulation to allow to
analyze the buckling of longitudinal bars in reinforced
concrete columns taking
into account the tie spacing, the diameter and arrangement
of the ties in the cross
section and the longitudinal bar diameter. For this purpose
an analytical method
for the evaluation of the buckling load of longitudinal
bars is described, as a
function of the constraint imposed by the axial or flexural
stiffness of the stirrups.
The longitudinal bar is considered as a column deforming
according to thin beam
theory. The tie action is described either by a set
discrete elastic supports or by a
continuous elastic foundation. The theoretical analysis
considers the column with
one or more deformation modes, with some degree of
nonlinearity, including the
analysis of post-critical equilibrium paths. As a result of
this study, rational
criteria for spacing and sizing of transversal
reinforcement are derived, allowing
to study different alternatives in an abacus of simple use
for design. Several
comparisons with the results obtained experimentally by
other authors in
reinforced concrete columns are presented, allowing for an
evaluation of the
validity of the theoretical developments and the rational
design methodology
proposed herein.
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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 Civil<br>The 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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Mollazadeh, Mohammad Hassan. "Load introduction into concrete-filled steel tubular columns." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/load-introduction-into-concretefilled-steel-tubular-columns(6750e9ae-b2c4-46d4-858f-c4a3f238439c).html.
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Concrete-Filled Steel Tubular (CFST) columns are increasingly being used because of their many advantages, including high strength, high ductility, and higher fire resistance than conventional steel or concrete columns of the same size. In order to maximise the advantages of CFST column, composite action of the column should be ensured. In realistic structures, the load is not directly applied to the entire CFST column section and is introduced from the beam-column connection. Simple shear connections, which are usually preferred in constructions, are only connected to the external face of the steel tube and there is an issue about how this load is introduced to the concrete core, through the bond at the steel/concrete interface. There are fundamental errors in the load introduction mechanism assumed in various current design methods. Furthermore, based on this erroneous load introduction mechanism, construction methods, such as placing shear connectors inside the steel tube or using through-column plates, are recommended to ensure complete load introduction. However, these methods are either impractical or uneconomical. The aim of this project, therefore, is to develop a thorough understanding of the load introduction mechanism and to use the new insights to assess design implications, for both ambient temperature and fire safety design. The research has been conducted through physical testing, extensive numerical modelling and detailed analytical derivations. A series of new load introduction tests, in which square CFST columns are loaded through simple fin plate connections, are carried out. These tests are designed to investigate the effects of changing column lengths below and above the connection, the effectiveness of using shear connectors inside the steel tube below the connection (according to Eurocode 4) and using a cap plate on the column top for load introduction into the concrete core. The test results indicate that the connection load is introduced to the concrete core through the column length above and within the connection or the cap plate on top of the column. This is different from the currently assumed mechanism of load introduction which assumes that load introduction occurs from underneath the connection. Below the connection, there is transfer of forces from the steel tube to the concrete core, but the total force in the column remains unchanged. Consequently, using shear connectors below the connection is ineffective in increasing CFST column strength, as has been demonstrated by the tests. The physical tests are supplemented by an extensive numerical parametric study to check whether the conclusions are applicable to different design conditions and to provide data for development of a new design method. The parameters include: section geometry (square, circular, and rectangular), position of load application to CFST column, dimensions of the square column cross-section, steel tube thickness, connection length, column length above the connection, column length below the connection, and maximum bond stress at the steel-concrete interface. The numerical simulation results confirm the experimental observations. Furthermore, the numerical simulation results indicate that the entire column length and the entire perimeter of the steel-concrete interface above and within the connection are engaged in load introduction. Based on the experimental and numerical simulation results, a simple calculation method has been proposed to calculate the column cross-section resistance under compression. According to this equation, the concrete compression resistance to the composite column is the minimum of the plastic resistance or the bond strength within and above the connection. This gives rise to a “concrete strength reduction factor” to account for incomplete load introduction, being the ratio of the load introduced to the concrete core through the interface bond to the concrete plastic resistance. Based on the new load introduction calculation method and using representative values of column dimensions and concrete cylinder strength, it has been demonstrated that complete load introduction can be achieved in almost all practical arrangements of concrete-filled tubular construction. For slender CFST column design, this concrete strength reduction factor should also be used to calculate the CFST column cross-section flexural stiffness. For a CFST column under combined axial compression and bending, the concrete strength reduction factor should be used when calculating the compression force, but should be ignored when calculating the bending resistance because composite action is not necessary for bending of the CFST column. The new load introduction mechanism induces additional compression in the concrete core and possible tension in the steel tube above the connection. Therefore, the concrete core of the column above the connection in multi-storey construction should be designed to resist the additional compression force. For the steel tube, in ambient temperature design, the steel contribution ratio (steel section resistance/plastic resistance of composite cross-section) of the top floor column should be at least 0.25. For fire resistance design, the steel contribution ratio of the top floor columns, those on the floor below the top floor, and those two floors below the top floor, should not be less than 0.5, 0.33, and 0.25 respectively.
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Gurbuz, Tuba. "Impact performance and mitigation of reinforced concrete columns." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/122182/1/Tuba_Gurbuz_Thesis.pdf.
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This thesis studies the behavior of RC columns vulnerable to vehicular impacts and develops an appropriate retrofitting technique to mitigate the adverse effects of the impact. The findings of this research will inform new designs and retrofitting of existing designs to enhance their safety and protect the structures they support
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Thompson, Theron James. "The effects of long-duration earthquakes on concrete bridges with poorly confined columns." Online access for everyone, 2004. http://www.dissertations.wsu.edu/Thesis/Fall2004/T%5FThompson%5F090304.pdf.
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Perea, Tiziano. "Analytical and experimental study on slender concrete-filled steel tube columns and beam-columns." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37303.
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The use of composite steel-concrete columns and beam-columns in many structural systems is increasing globally due to the intrinsic synergy when these materials are designed and detailed together properly. However, limited test data are available to justify the structural system response factors and comprehensive design equations in current design specifications. This research, through the testing of 18 full-scale, slender concrete-filled steel tube (CFT) beam-columns, attempts to address the latter need. The circular and rectangular CFT specimens tested for this research are by far the longest and the most slender full-scale CFT members tested worldwide. These CFT specimens were subjected to a complex load protocol that includes pure compression, uniaxial and biaxial bending combined with compression, pure torsion, and torsion combined with compression. In addition, data from the hydrostatic pressure on the steel tubes due to the fresh concrete at casting was evaluated. The single most important contribution of this research is the clarification of the interaction between strength and stability in slender composite concrete-filled columns and beam-columns. Parallel to the experimental study, advanced computational analyses were carried out to calibrate material and element models that characterize the salient features of the observed CFT response, such as steel local buckling and residual stresses, concrete confinement, stability effects, strength, and stiffness degradation, among others. Based on the observed behavior, simplified guidelines for the computation of the strength and stiffness parameters for CFT columns and beam-columns are proposed for design purposes.
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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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Kim, Dong Keon. "A Database for Composite Columns." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7126.
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A database of composite column tests was augmented and utilized to evaluate the proposed AISC 2005 provisions. The database consists of column and beam-column steel-concrete columns (or encased, SRC), circular concrete filled tubes (CCFT), and rectangular concrete filled tube (RCFT). Information on material and geometric properties on each specimen was summarized. The database includes 119 SRC columns, 136 SRC beam-columns, 312 circular CFT columns, 198 circular CFT beam-columns, 222 rectangular CFT columns and 194 rectangular CFT beam-columns. The database has a total of 1181 specimens, an addition of 451 specimens over those in the original database (Aho 1996).
The data on each specimen was analyzed and compared with current design provision for composite columns (AISC 1999 and Eurocode 4), and reassessed by the upcoming 2005 AISC specification. The data indicates that the Eurocode gives good predictions for columns and the AISC 2005 method performs very well for beam-columns. For rectangular CFT columns, all three methods predict the ultimate capacity very well. The main improvement for the AISC 2005 method is its ability to handle specimens which have high yield stress and/or high strength concrete.
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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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Elghazouli, Ahmed Youssef. "Earthquake resistance of composite beam-columns." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/7906.
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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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Endeshaw, Mesay Abebaw. "Seismic retrofit of rectangular bridge columns using CFRP wrapping." Online access for everyone, 2008. http://www.dissertations.wsu.edu/Thesis/Spring2008/M_Endeshaw_030408.pdf.
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Xiang, Zhen Xian. "Punching shear strength of waffle slabs at internal columns." Thesis, University of Leeds, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367299.
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Rocca, Silvia. "Experimental and analytical evaluation of FRP-confined large size reinforced concrete columns." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/Rocca_09007dcc803bfaf5.pdf.
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Thesis (Ph. D.)--University of Missouri--Rolla, 2007.<br>Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed February 12, 2008) Includes bibliographical references.
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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.
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Microreproduction of original thesis.<br>Thesis (PhD)--Stellenbosch University, 1990.<br>Some digitised pages may appear illegible due to the condition of the original microfiche copy.<br>ENGLISH ABSTRACT: see item for full text<br>AFRIKAANSE OPSOMMING: sien item vir volteks.
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Koen, Johan Alexander. "An investigation into the axial capacity of eccentrically loaded concrete filled double skin tube columns." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96797.
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Thesis (MSc)--Stellenbosch University, 2015.<br>ENGLISH ABSTRACT: Concrete filled double skin tube (CFDST) columns is a new method of column construction. CFDST columns consists of two steel hollow sections, one inside the other, concentrically aligned. The cross-sections of the two hollow sections does not have to be the same shape. Concrete is cast in between the two hollow sections resulting in a CFDST. This study only considers CFDST columns constructed with circular steel hollow sections. The advantages of CFDST construction include:
● The inner and outer steel hollow sections replaces the traditional steel reinforcement that would be used in a normal reinforced concrete column. This reduces the construction time since there is no need to construct a reinforcing cage.
● The steel hollow sections acts as a stay in place formwork, eliminating the need for traditional formwork. This also reduces construction time.
● The steel hollow sections confine the concrete, making it more ductile and increasing its yield strength.
The objective of this study is to identify methods that can predict the axial capacity of eccentrically loaded circular CFDST columns. Methods chosen for the investigation are:
1. Finite element model (FEM). A model was developed to predict the behaviour of eccentrically loaded CFDST columns. The FE model uses a concrete material model proposed in literature for stub columns. The aim was to determine whether the material model is suited for this application.
2. The failure load of CFDST columns under concentric loading was calculated using a model obtained in literature. These capacities were compared to the experimental test results of eccentrically loaded CFDST columns to establish a correlation.
This study found that the concrete material model used does not adequately capture the behaviour resulting in the axial response of the column being too stiff. The difference between the eccentrically loaded experimental test results and the calculated concentrically loaded capacity showed a clear trend that could be used to predict the capacity of eccentrically loaded CFDST columns.<br>AFRIKAANSE OPSOMMING: Beton-gevulde dubbel laag pyp (BGDLP) kolomme is ‘n nuwe metode van kolom konstruksie. BGDLP kolomme bestaan uit twee staal pyp snitte, die een binne die ander geplaas met hul middelpunte opgelyn, die dwarssnit van die twee pype hoef nie dieselfde vorm te wees nie. Beton word dan in die wand tussen die twee pyp snitte gegiet. Die resultaat is ‘n hol beton snit. Hierdie studie handel slegs oor BGDLP kolomme wat met ronde pyp snitte verwaardig is. Die volgende voordele kan aan BGDLP toegeken word:
● Die binne en buite staalpype vervang die tradisionele staal bewapening was in normale bewapende-beton gebruik sou word. Dus verminder dit die tyd wat dit sal neem om die kolom op te rig.
● Die staalpypsnitte is ook permanente vormwerk. Dit doen dus weg met die gebruik van normale bekisting, wat ook konstruksie tyd spaar.
● Die buite-staalpypsnit bekamp die uitsetting van die beton onder las. Hierdie bekamping veroorsaak dat die beton se gedrag meer daktiel is en ‘n hoër falings spanning kan bereik.
Die doel van die studie is om metodes te identifiseer wat gebruik kan word om die aksiale kapasiteit onder eksentriese laste van BGDLP kolomme te bepaal. Twee metodes was gekies:
1. Eindige element model. ‘n Model was ontwikkel om die gedrag van BGDLP kolomme te voorspel. Die mikpunt was om te bepaal of ‘n beton materiaal gedrag model vanuit die literatuur gebruik kan word om BGDLP kolomme te modelleer.
2. Die swiglas van BGDLP kolomme onder konsentriese belasting was bereken vanaf vergelykings uit die literatuur. Hierdie swiglaste was vergelyk met die eksperimentele toets resultate vir eksentriese belaste BGDLP kolomme om ‘n korrelasie te vind.
Hierdie studie het bewys dat die beton materiaal model uit die literatuur kan nie gebruik word om die swiglaste van BGDLP kolomme te bepaal nie. Die model het die gedrag te styf gemodelleer. Die verskil tussen die berekende konsentriese belaste swiglas en die eksperimentele resultate van eksentriese BGDLP kolomme was voorspelbaar en kan gebruik word om die swiglas van eksentriese belaste BGDLP kolomme te voorspel.
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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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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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Bayrak, Oguzhan. "Seismic performance of rectilinearly confined high strength concrete columns." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq41101.pdf.
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Mes, Derek. "Seismic retrofitting of concrete bridge columns by external prestressing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0005/MQ45242.pdf.
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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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Hart, Steven D. "Performance of confined concrete columns under simulated life cycles." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/607.
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