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1
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.
Texto completo da fonteResumo:
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.
2
Wong, Koon-Wan. "Non-linear behaviour of reinforced concrete frames /". Title page, contents and abstract only, 1989. http://web4.library.adelaide.edu.au/theses/09PH/09phw872.pdf.
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3
Kenyon, Jonn Mark. "Non-linear analysis of reinforced concrete plane frames /". Title page, table of contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phk368.pdf.
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4
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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Cassidy, Eric Dana. "Development and Structural Testing of FRP Reinforced OSB Panels for Disaster Resistant Construction". Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/CassidyED2002.pdf.
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Yuan, Lie Ping. "Partial interaction behaviour of bolted side plated reinforced concrete beams". Title page, abstract and contents only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phl7161.pdf.
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Includes bibliographical references (p. 185-189) Aims to determine the effect of partial interaction on the behaviour of the concrete beam, plate and bolt connector components of the composite plated beam. Develops design rules for the determination of the ultimate capacity for bolted plate reinforced composite beams.
7
Samman, Tamim Abdulhadi. "Indeterminate reinforced concrete frames subjected to inelastic cyclic deformation". Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184307.
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Four full-size statically indeterminate reinforced concrete frames with two symmetrical bays were tested to obtain sufficient data to evaluate the adequacy of the current ACI-ASCE Committee 352 design recommendations, as well as to determine whether a relaxation of some of the limits in these guidelines can be justified. Each specimen contained three 8.5-foot-long columns, connected at mid-height by two 9-foot-long beams. Initially, a constant axial load was applied to each column. The specimens were then subjected to a displacement-controlled loading schedule to simulate the type of displacements a frame may experience during a severe earthquake. In designing the specimens, the latest recommendations of the ACI-ASCE Committee 352 and the ACI building code ACI 318-83 were satisfied except for the following modifications: (1) the flexural strength ratio (M(R)) in the second specimen was reduced from 1.4 to 1.2, (2) the shear-stress factors (γ) in the joints of the third specimen were increased from 12 and 15 to 15 and 20 for the exterior and interior joints respectively, and (3) the number of the transverse reinforcements inside the right exterior joint in the fourth specimen was reduced from 4 to 2 sets of hoops. The conclusion inferred from the results indicate that for drift levels within the elastic range, the elongations and the rotations of the beam regions near the faces of the columns, in addition to the joint shear strains, were not affected by the design values for the primary variables in the last three specimens. For larger excursions into the inelastic range, the relaxation of the current Committee 352 design recommendations in the last three specimens not only showed a significant effect in reducing the elongations and the rotations of the beams, or in increasing the joint shear strains but led to lower energy dissipation of the specimens. Consequently, the current design guidelines by the ACI-ASCE Committee 352 yield statically indeterminate frames which exhibit sufficient ductility.
8
Sheats, Matthew Reed. "Rehabilitation of reinforced concrete pier caps using carbon fiber reinforced composites". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19490.
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Gravina, Rebecca Jane. "Non-linear overload behaviour and ductility of reinforced concrete flexural members containing 500MPa grade steel reinforcement". Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phg777.pdf.
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Includes corrigenda (inserted at front) and list of publications published as a result of this research. Includes bibliographical references (leaves 192-199) Investigates the overload behaviour and modes of collapse of reinforced concrete flexural members containing 500MPa grade reinforcing steel and evaluates the adequacy of current ductility requirements for design according to AS 3600 to ensure strength and safety.
10
Lam, Wai-yin, e 林慧賢. "Plate-reinforced composite coupling beams: experimental and numerical studies". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37311797.
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11
Chau, Siu-lee, e 周小梨. "Effects of confinement and small axial load on flexural ductility of high-strength reinforced concrete beams". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31997661.
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12
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.
13
Draper, Jeffrey Dean. "Neural networks and non-destructive test/evaluation methods". Thesis, College Park, Maryland : University of Maryland, College Park, 1992. http://handle.dtic.mil/100.2/ADA254802.
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Thesis (M.S. in Civil Engineering)--University of Maryland, College Park, 1992."A scholarly paper submitted to Assistant Professor Ian Flood." Description based on title screen as viewed on April 16, 2009. Includes bibliographical references (p. 49-52). Also available in print.
14
Venkata, Vijai Kumar. "Development and testing of hurricane resistant laminated glass fiber reinforced composite window panels /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426111.
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15
Zerkane, Ali S. H. "Cyclic Loading Behavior of CFRP-Wrapped Non-Ductile Reinforced Concrete Beam-Column Joints". PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3000.
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Use of fiber reinforced polymer (FRP) material has been a good solution for many problems in many fields. FRP is available in different types (carbon and glass) and shapes (sheets, rods, and laminates). Civil engineers have used this material to overcome the weakness of concrete members that may have been caused by substandard design or due to changes in the load distribution or to correct the weakness of concrete structures over time specially those subjected to hostile weather conditions. The attachment of FRP material to concrete surfaces to promote the function of the concrete members within the frame system is called Externally Bonded Fiber Reinforced Polymer Systems. Another common way to use the FRP is called Near Surface Mounted (NSM) whereby the material is inserted into the concrete members through grooves within the concrete cover. Concrete beam-column joints designed and constructed before 1970s were characterized by weak column-strong beam. Lack of transverse reinforcement within the joint reign, hence lack of ductility in the joints, and weak concrete could be one of the main reasons that many concrete buildings failed during earthquakes around the world. A technique was used in the present work to compensate for the lack of transverse reinforcement in the beam-column joint by using the carbon fiber reinforced polymer (CFRP) sheets as an Externally Bonded Fiber Reinforced Polymer System in order to retrofit the joint region, and to transfer the failure to the concrete beams. Six specimens in one third scale were designed, constructed, and tested. The proposed retrofitting technique proved to be very effective in improving the behavior of non-ductile beam-column joints, and to change the final mode of failure. The comparison between beam-column joints before and after retrofitting is presented in this study as exhibited by load versus deflection, load versus CFRP strain, energy dissipation, and ductility.
16
Aules, Wisam Amer. "Behavior of Non-Ductile Slender Reinforced Concrete Columns Retrofit by CFRP Under Cyclic Loading". PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4804.
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In the Middle East region and many countries in the world, older reinforced concrete (RC) columns are deemed to be weak in seismic resistance because of their low amount of reinforcement, low grades of concrete, and large spacing between the transverse reinforcement. The capacity of older RC columns that are also slender is further reduced due to the secondary moments. Appropriate retrofit techniques can improve the capacity and behavior of concrete members. In this study, externally bonded Carbon Fiber Reinforced Polymer (CFRP) retrofit technique was implemented to improve the behavior of RC columns tested under constant axial load and cyclic lateral load. The study included physical testing of five half-scale slender RC columns, with shear span to depth ratio of 7. Three specimens represented columns in a 2-story, and two specimens represented columns in a 4-story building. All specimens had identical cross sections, reinforcement detail, and concrete strength. Two specimens were control, two specimens were retrofit with CFRP in the lateral direction, and one specimen retrofit in the longitudinal and lateral directions. A computer model was created to predict the lateral load-displacement relations. The experimental results show improvement in the retrofit specimens in strength, ductility, and energy dissipation. The effect of retrofitting technique applied to two full-scale prototype RC buildings, a 2-story and a 4-story building located in two cities in Iraq, Baghdad, and Erbil, was determined using SAP2000.
17
Lopez, Ibaceta Alvaro Francisco. "Seismic Performance of Substandard Reinforced Concrete Bridge Columns under Subduction-Zone Ground Motions". PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4977.
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A large magnitude, long duration subduction earthquake is impending in the Pacific Northwest, which lies near the Cascadia Subduction Zone (CSZ). Great subduction zone earthquakes are the largest earthquakes in the world and are the sole source zones that can produce earthquakes greater than M8.5. Additionally, the increased duration of a CSZ earthquake may result in more structural damage than expected. Given such seismic hazard, the assessment of reinforced concrete substructures has become crucial in order to prioritize the bridges that may need to be retrofitted and to maintain the highway network operable after a major seismic event. Recent long duration subduction earthquakes occurred in Maule, Chile (Mw 8.8, 2010) and Tohoku, Japan (Mw 9.0, 2011) are a reminder of the importance of studying the effect of subduction ground motions on structural performance. For this purpose, the seismic performance of substandard circular reinforced concrete bridge columns was experimentally evaluated using shake table tests by comparing the column response from crustal and subduction ground motions. Three continuous reinforced columns and three lap-spliced columns were tested using records from 1989 Loma Prieta, 2010 Maule and 2011 Tohoku. The results of the large-scale experiments and numerical studies demonstrated that the increased duration of subduction ground motions affects the displacement capacity and can influence the failure mode of bridge columns. Furthermore, more damage was recorded under the subduction ground motions as compared to similar maximum deformations under the crustal ground motion. The larger number of plastic strain cycles imposed by subduction ground motions influence occurrence of reinforcement bar buckling at lower displacement compared to crustal ground motions. Moreover, based on the experimental and numerical results, subduction zone ground motion effects are considered to have a significant effect on the performance of bridge columns. Therefore, it is recommended to consider the effects of subduction zone earthquakes in the performance assessment of substandard bridges, or when choosing ground motions for nonlinear time-history analysis, especially in regions prone to subduction zone mega earthquakes. Finally, for substandard bridges not yet retrofitted or upgraded seismically, the following performance limit recommendation is proposed: for the damage state of collapse, which is related to the ODOT's Life Safety performance level, the maximum strain in the longitudinal reinforcement should be reduced from 0.09 (in./in.) to a value of 0.032 (in./in.) for locations where subduction zone earthquakes are expected, to take into consideration the occurrence of bar buckling.
18
Garth, John Stuart. "Experimental Investigation of Lateral Cyclic Behavior of Wood-Based Screen-Grid Insulated Concrete Form Walls". PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1857.
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Insulated concrete forms (ICFs) are green building components that are primarily used for residential wall construction. Unlike most polystyrene based ICF variants, the Faswall ICFs used in these experiments were significantly denser because they were made from recycled wood particles and cement. The current design approach for structures constructed with this type of wall form only allows the designer to consider the contribution of the reinforced concrete cores. Previous research has shown that this approach may be conservative. This project experimentally evaluated the lateral structural response of these types of grid ICF walls under increasing amplitude of in-plane cyclic loading. Two different height-to-length (aspect) ratios (approximately 2:1 and 1:1) were investigated, as was the effect of simultaneous gravity load. Furthermore, the reinforced concrete grid was exposed for each aspect ratio in order to examine the contribution of the ICF blocks to the lateral response. Analyses of hysteretic behaviors and failure modes indicated conservatism in the current design approach for estimating lateral strength and ignoring the beneficial contribution of the ICF blocks to overall performance. The presence of the wall forms increased the lateral shear capacity of the walls by an average of 42% (compared to the walls with forms removed), while also increasing the deformation capacity by an average of 102%. Furthermore, by considering an additional gravity load of 10 kips-per-lineal-foot (klf), the shear resistance of the walls increased by 32% (versus walls only subjected to self-weight), on average, and the deformation capacity of the walls increased by an average of 19%. Comparisons of the experimental results to several design equations led to the recommendation of a design equation that was previously accepted for another type of ICF system.
19
Murahidy, Alexander Gustav. "Design, construction, dynamic testing and computer modelling of a precast prestressed reinforced concrete frame building with rocking beam-column connections and ADAS elements". Thesis, University of Canterbury. Department of Civil Engineering, 2004. http://hdl.handle.net/10092/2514.
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Following a major earthquake event, essential public amenities such as medical facilities and
transport networks need to remain functional - not only to fulfil their ongoing role in serving
the community but also to cope with the added and immediate demand of a population
affected by a natural disaster. Furthermore, the economic implications of wide spread damage
to housing and commercial facilities should not be discounted. A shift in design approach is
required that is consistent with current trends towards performance based building design. The
present aim is to achieve seismic energy dissipation during the earthquake event, without the
aftermath of damage to structural elements, whilst maintaining design economies.
Structures permitted to rock on their foundations and provide recoverable rotations at the
beam-column interfaces offer significant advantages over those using conventional ductile
detailing. A jointed construction philosophy can be applied whereby structural elements are
connected with unbonded prestressing tendons. Supplemental damping is provided by
replaceable flexural steel components designed to deform inelastically. For this research a
multi-storey test building of one quarter scale has been constructed and tested on an
earthquake simulator at the University of Canterbury. A computer model has been developed
and a set ofpreliminary design procedures proposed.
20
Bothma, Jacques. "The structural use of synthetic fibres : thickness design of concrete slabs on grade". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85877.
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Thesis (MScEng)-- Stellenbosch University, 2013.ENGLISH ABSTRACT: Concrete is used in most of the modern day infrastructure. It is a building material for which there exist various design codes and guidelines for its use and construction. It is strong in compression, but lacks tensile strength in its fresh and hardened states and, when unreinforced, fails in a brittle manner. The structural use of synthetic fibres in concrete is investigated in this study to determine its effect on enhancing the mechanical properties of concrete. Slabs on grade are used as the application for which the concrete is tested. The material behaviour is investigated in parallel with two floor design theories. These are the Westegaard theory and the Yield-Line theory. The Westegaard theory uses elastic theory to calculate floor thicknesses while the Yield-Line theory includes plastic behaviour. Conceptual designs are performed with the two theories and material parameters are determined from flexural tests conducted on synthetic fibre reinforced concrete (SynFRC) specimens. Large scale slab tests are performed to verify design values from the two theories. Higher loads till first-crack were measured during tests with concrete slabs reinforced with polypropylene fibres than for unreinforced concrete. It is found that the use of synthetic fibres in concrete increases the post-crack ductility of the material. The Westegaard theory is conservative in its design approach by over-estimating design thicknesses. This was concluded as unreinforced slabs reached higher failure loads than predicted by this theory. The Yield-Line theory predicts design thicknesses more accurately while still accounting for the requirements set by the ultimate- and serviceability limit states. By using SynFRC in combination with the Yield-Line theory as design method, thinner floor slabs can be obtained than with the Westegaard theory.
AFRIKAANSE OPSOMMING: Beton word gebruik as boumateriaal in meeste hedendaagse infrastruktuur. Daar bestaan verskeie ontwerp kodes en riglyne vir die gebruik en oprig van beton strukture. Alhoewel beton sterk in kompressie is, het beton ‘n swak treksterkte in beide die vars- en harde fases en faal dit in ‘n bros manier indien onbewapen. Die gebruik van sintetiese vesels in beton word in hierdie projek ondersoek om die invloed daarvan op die eienskappe van die meganiesegedrag van beton te bepaal. Grond geondersteunde vloere word as toepassing gebruik. Parallel met die materiaalgedrag wat ondersoek word, word twee ontwerpsteorieë ook ondersoek. Dit is die teorie van Westegaard en die Swig-Lyn teorie. Die teorie van Westegaard gebruik elastiese teorie in ontwerpsberekeninge terwyl die Swig-Lyn teorie ‘n plastiese analise gebruik. ‘n Konseptuele vloerontwerp is gedoen deur beide die ontwerpsmetodes te gebruik. Materiaalparameters is bepaal deur buig-toetse uit te voer op sintetiesevesel-bewapende beton. Grootskaalse betonblaaie is gegiet en getoets om die akkuraatheid van die twee metodes te verifieer. Die betonblaaie wat bewapen was met polipropileen vesels het groter laste gedra tot by faling as die blaaie wat nie bewapen was nie. Die vesels verbeter die gedrag van beton in die plastiese gebied van materiaalgedrag deurdat laste ondersteun word nadat die beton alreeds gekraak het. Die Westegaard teorie kan as konserwatief beskou word deurdat dit vloerdiktes oorskat. Hierdie stelling is gegrond op eksperimentele data wat bewys dat onbewapende betonblaaie groter laste kan dra as wat voorspel word deur die Westegaard teorie. Die Swig-Lyn teorie voorspel ontwerpsdiktes meer akkuraat terwyl daar steeds aan die vereistes van swigting en diensbaarheid voldoen word. Deur gebruik te maak van sintetiese vesels en die Swig-Lyn teorie kan dunner betonblaaie ontwerp word as met die Westegaard teorie.
21
Ghasemi, Sahar. "Innovative Modular High Performance Lightweight Decks for Accelerated Bridge Construction". FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2248.
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At an average age of 42 years, 10% of the nation’s over 607,000 bridges are posted for load restrictions, with an additional 15% considered structurally deficient or functionally obsolete. While there are major concerns with decks in 75% of structurally deficient bridges, often weight and geometry of the deck further limit the load rating and functionality of the bridge. Traditional deck systems and construction methods usually lead to prolonged periods of traffic delays, limiting options for transportation agencies to replace or widen a bridge, especially in urban areas.
The purpose of this study was to develop a new generation of ultra-lightweight super shallow solid deck systems to replace open grid steel decks on movable bridges and as well serve as a viable alternative in bridge deck replacements across the country. The study has led to a lightweight low-profile asymmetric waffle deck made with advanced materials. The asymmetry comes from the arrangement of primary and secondary ribs, respectively perpendicular and parallel to the direction of traffic. The waffle deck is made with ultrahigh performance concrete (UHPC) reinforced with either high-strength steel (HSS) or carbon fiber reinforced polymer (CFRP) reinforcement. With this combination, the deck weight was limited to below 21 psf and its overall depth to only 4 inch, while still meeting the strength and ductility demands for 4 ft. typical stringer spacing. It was further envisioned that the ultra-high strength of UHPC is best matched with the high strength of HSS or CFRP reinforcement for an efficient system and the ductile behavior of UHPC can help mask the linear elastic response of CFRP reinforcement and result in an overall ductile system. The issues of consideration from the design and constructability perspectives have included strength and stiffness, bond and development length for the reinforcement, punching shear and panel action. A series of experiments were conducted to help address these issues. Additionally full-size panels were made for testing under heavy vehicle simulator (HVS) at the accelerated pavement testing (APT) facility in Gainesville. Detailed finite element analyses were also carried out to help guide the design of this new generation of bridge decks. The research has confirmed the superior performance of the new deck system and its feasibility.
22
Ogura, Hiroki, Venkatesh Naidu Nerella e Viktor Mechtcherine. "Developing and Testing of Strain-Hardening Cement-Based Composites (SHCC) in the Context of 3D-Printing". Molecular Diversity Preservation International (MDPI), 2018. https://tud.qucosa.de/id/qucosa%3A33325.
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Incorporating reinforcement into the practice of digital concrete construction, often called 3D-concrete-printing, is a prerequisite for wide-ranging, structural applications of this new technology. Strain-Hardening Cement-based Composites (SHCC) offer one possible solution to this challenge. In this work, printable SHCC were developed and tested. The composites could be extruded through a nozzle of a 3D-printer so that continuous filaments could be deposited, one upon the other, to build lab-scaled wall specimens without noticeable deformation of the bottom layers. The specimens extracted from the printed walls exhibited multiple fine cracks and pronounced strain-hardening characteristics under uniaxial tensile loading, even for fiber volume fractions as low as 1.0%. In fact, the strain-hardening characteristics of printed specimens were superior to those of mold-cast SHCC specimens.
23
Al-Soudani, Maha. "Diagnosis of reinforced concrete structures in civil engineering by GPR technology : development of alternate methods for precise geometric recognition". Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30090.
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La méconnaissance de la géométrie réelle d'une structure mène à une évaluation incorrecte de son état. Par conséquent, une estimation imprécise de sa capacité portante, sa durabilité, sa stabilité et la nécessité de mettre en place une réparation ou un renforcement. En outre, l'optimisation du temps requis pour le processus de réparation a besoin de bien connaître les différentes parties de la structure à évaluer et également pour éviter les zones critiques telles que les aciers, les câbles, etc., lors de la réparation. Par conséquent, il est nécessaire d'utiliser des techniques d'évaluation non destructive (END) afin de connaître la géométrie réelle de la structure, notamment l'emplacement des armatures dans les structures en béton armé. Le GPR est considéré comme une technique non-destructive idéale pour détecter et localiser les renforts. Cependant, sa précision de localisation est limitée. Le but de ce projet de recherche a donc été d'accroître la précision du GPR en matière de reconnaissance géométrique interne de structures en béton armé. L'objectif principal de cette étude est de localiser précisément le positionnement des armatures dans le plan ausculté ainsi qu'en profondeur. Pour atteindre cet objectif, une nouvelle méthodologie de mesures et du traitement des signaux GPR a été proposée dans cette étude. Plusieurs configurations d'acquisition de données en utilisant des signaux simulés sont testées pour proposer et développer un algorithme d'imagerie du milieu de propagation afin de définir sa géométrie interne et de localiser précisément les barres de renforcement. Des traitements supplémentaires sont appliqués pour améliorer la précision de la détection et pour identifier les différentes interfaces dans le milieu testé. L'algorithme et le traitement sont appliqués aux signaux simulés. Des validations expérimentales ont ensuite été appliquées aux signaux réels acquis sur différentes dalles en béton armé. L'objectif est de tester la capacité de l'algorithme d'imagerie proposé pour localiser différents objets enfouis. Les résultats encourageants montrent que cet algorithme est capable d'estimer la position de différents objets enfouis et pas uniquement les armatures avec une erreur d'estimation de (0-1) mm. Les performances de l'algorithme ont été comparées à celles d'une méthode de migration et aux résultats de mesure obtenus avec un pachomètre. Ces comparaisons ont systématiquement révélé une meilleure précision de la localisation avec l'algorithme développé.Une autre étude a été proposée dans ce travail en testant l'algorithme avec des signaux réels modifiés. Ces signaux sont produits en réduisant le gain le moins possible. La conclusion la plus évidente de cette étude est que l'algorithme proposé est capable de localiser les différents objets même si les signaux réfléchis par eux sont de faible amplitudeLack of acquaintance in the real geometry of a structure leads to incorrect evaluation of its state. Consequently, this will lead to inaccurate estimation of bearing capacity, durability, stability and moreover, the need for repair or strengthening. Furthermore, optimization of the required time for repair process needs to well recognize the parts of structure to be assessed and also to avoid the critical zones such as reinforcing bars, cables, etc., during repairing. Therefore; it becomes necessary to use a non-destructive testing (NDT) method in order to know the real geometry of structure in particular, the location of reinforcements in reinforced concrete structures. GPR is considered as an ideal non-invasive technique in detecting and locating these reinforcements. However, its accuracy in localization is limited. The aim of this research project has therefore been to increase the accuracy of GPR in recognizing the internal geometry of reinforced concrete structures. The main objective of this study is to locate accurately the position of reinforcements into three dimensions. To achieve this purpose, a new methodology for GPR measurement and processing is proposed in this study.Several configurations of data acquisition using simulated signals are tested to propose and develop an appropriate imaging algorithm for the propagation medium to imagine its internal geometry and to locate accurately the reinforcing bars. Further processing are applied to improve the accuracy of detection and to identify the different interfaces in the tested medium. Both algorithm and processing are applied on simulated signals. Subsequent experimental validations have been applied using real signals acquired from different real reinforced concrete slabs. The goal is to test the ability of proposed imaging algorithm for the localization of different targets. The encouraging results indicate that this algorithm is able to estimate the position of different buried targets and not only the reinforcing bars with an estimation error of (0-1)mm.The performance of proposed algorithm has compared to those of migration method and to the results obtained from pachometer. These comparisons have systematically revealed a better localization accuracy using the developed algorithm.Another study has been proposed in this work by testing the algorithm using modified real signals. These signals are produced by reducing the gain as less as possible. The most obvious finding to emerge from this study is that the proposed algorithm is able to localize the different goals even if the signals reflected by them are of low amplitude
24
Graeff, Matthew Kent. "The Repair of Laterally Damaged Concrete Bridge Girders Using Carbon Fiber Reinforcing Polymers (CFRP)". UNF Digital Commons, 2012. http://digitalcommons.unf.edu/etd/592.
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In recent years the use of carbon fiber reinforcing polymers (CFRP) to repair damaged structural components has become more accepted and practiced. However, the current reference for designing FRP systems to repair and strengthen reinforced concrete (RC) and prestressed concrete (PSC) girders has limitations. Similarly, very few resources address solutions for the debonding problem associated with CFRP laminates or the use of CFRP laminates to repair structural members with pre-existing damage. The included experimental program consists of testing both RC and PSC girders with simulated lateral damage and CFRP repairs. A total of 34 RC beams were statically tested under a 4-point loading until failure and had cross-section dimensions of 5” x 10” (14cm x 25.4cm), were 8’ long (2.44m), and were reinforced with either #3 or #4 mild steel rebar. 13 PSC girders having cross-section dimensions representing a half-scaled AASHTO type II shape, were 20’ long (6.1m), and were prestressed with five 7/16” (11.1mm) diameter low-lax 7-wire strands. Ten of the PSC girders were statically loaded until failure under a 4-point testing setup, but 3 PSC girders were dynamically tested under fatigue loading using a 3-point arrangement. Different configurations of CFRP laminates, number and spacing of CFRP transverse U-wraps, and amount of longitudinal CFRP layers are studied. The results present the flexural behavior of all specimen including load-deflection characteristics, strain characteristics, and modes of failure. Ultimately, results are used to recommend important considerations, needed criteria, and proper design procedures for a safe and optimized CFRP repair configuration.
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Bernard, Lukáš. "Stavební průzkum a diagnostika železobetonové konstrukce". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409951.
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This diploma thesis deals with construction and technological survey of the reinforced concrete structure. The first part of the diploma thesis deals with the properties of the reinforced concrete and with the building survey methods applied in the second part of the thesis. The second part of the diploma thesis focuses on diagnostics of existing structure. More specifically, the hardness of the concrete is tested using a Schmidt hammer and then it is further specified by testing the cores. The reinforcement in the reinforced concrete is also tested using electromagnetic indicator, ground-penetrating radar, and chopped probes. Lastly, a static assessment of the selected girder and column is conducted.
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El-Gharib, Georges. "Evaluation of the Empirical Deck Design for Vehicular Bridges". UNF Digital Commons, 2014. http://digitalcommons.unf.edu/etd/489.
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This research evaluated the feasibility of the empirical design method for reinforced concrete bridge decks for the Florida Department of Transportation [FDOT]. There are currently three methods used for deck design: empirical method, traditional method and finite element method. This research investigated and compared the steel reinforcement ratios and the stress developed in the reinforcing steel for the three different methods of deck design. This study included analysis of 15 bridge models that met the FDOT standards. The main beams were designed and load rated using commercial software to obtain live load deflections. The bridges were checked to verify that they met the empirical method conditions based on the FDOT Structures Design Guidelines – January 2009. The reinforced concrete decks were designed using the traditional design method. Then the bridges were analyzed using three-dimensional linear finite element models with moving live loads. The reinforced concrete decks were designed using dead load moment, live load moment, and future wearing surface moment obtained from the finite element models. The required reinforcing steel ratio obtained from the finite element method was compared to the required reinforcing steel ratio obtained from traditional design method and the empirical design method. Based on the type of beams, deck thicknesses, method of analysis, and other assumptions used in this study, in most cases the required reinforcing steel obtained from the finite element design is closer to that obtained from the empirical design method than that obtained from the traditional design method. It is recommended that the reinforcing steel ratio obtained from the empirical design method be used with increased deck thicknesses to control cracking in the bridge decks interior bays.
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Thölken, Denise. "Efeito da rigidez de pilar parede no comportamento sísmico de edifício de concreto armado". Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/962.
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Este trabalho tem como objeto o estudo do efeito da rigidez de pilar parede no comportamento estrutural de edifícios de concreto armado submetidos a sismos. Foram consideradas as premissas da norma brasileira ABNT NBR15421:2006, que apresenta os critérios para projeto de estruturas resistentes a sismo. A análise linear com emprego dos métodos da norma - método das forças horizontais equivalentes, método espectral e histórico de aceleração no tempo - foi aplicada em edifícios com dois tipos de sistemas estruturais, sendo eles pórtico de concreto e sistema dual pórtico de concreto e pilar parede. Os resultados foram analisados nos pórticos de extremidade das estruturas nos sentidos longitudinal (x) e transversal (y), comparando-se os deslocamentos de cada pavimento e esforços cortantes, momento fletor e normal nas bases dos pilares. A comparação foi realizada entre os três métodos aplicados e os sistemas estruturais analisados.The aim of this work is to study the stiffness effect of wall columns on structural behavior of reinforced concrete buildings subjected to seismic action. The premises of the Brazilian standard ABNT NBR14521:2006 were considered, which presents criteria for earthquake resistant design of structures. The linear analysis employed the methods of the Brazilian standard - equivalent static load method, response spectrum analysis and time history method - were applied to buildings with two types of structural systems, namely concrete frame and dual system concrete frame and wall columns. The results were analyzed in edge frames structures in the longitudinal and transverse directions, comparing the displacement of each floor and shear, bending moment and axial forces on the bases of the columns. A comparison was made between the three methods applied and the structural systems analyzed.
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Lau, Shuk-lei. "Rehabilitation of reinforced concrete beam-column joints using glass fibre reinforced polymer sheets". Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B32001630.
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Kaděrová, Jana. "Multi-filament yarns testing for textile-reinforced concrete". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225556.
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The scope of the presented master thesis was the experimental study of multi-filament yarns made of AR-glass and used for textile-reinforced concrete. The behavior under the tensile loading was investigated by laboratory tests. A high number of yarn specimens (over 300) of six different lengths (from 1 cm to 74 cm) was tested to obtain statistically significant data which were subsequently corrected and statistically processed. The numerical model of the multi-filament bundle was studied and applied for prediction of the yarn performance and for later results interpretation. The model of n parallel filaments describes the behavior of a bundle with varying parameters representing different sources of disorder of the response and provides the qualitative information about the influence of their randomization on the overall bundle response. The aim of the carried experiment was to validate the model presumptions and to identify the model parameters to fit the real load-displacement curves. Unfortunately, due to unsuccessful correction of measured displacements devalued by additional non-linear contribution of the unstiff experiment device the load-displacement diagrams were not applicable to model parameters identification. The statistical evaluation was carried only for the maximal load values and the effect of the specimen size (length) on its strength was demonstrated. The size effect curve did not exclude the existence of spatial correlation of material mechanical properties modifying the classical statistical Weibull theory.
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Lam, Yuet-kee Jeffery, e 林悦基. "Full-range analysis of reinforced concrete members and frames". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42182268.
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Lau, Shuk-lei, e 劉淑妮. "Rehabilitation of reinforced concrete beam-column joints using glass fibre reinforced polymer sheets". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B32001630.
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Mahjoub-Moghaddas, Hamid. "Tensile and shear impact strength of concrete and fibre reinforced concrete". Thesis, Cardiff University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261439.
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黃玉平 e Yuping Huang. "Nonlinear analysis of reinforced concrete structures". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31233090.
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Huang, Yuping. "Nonlinear analysis of reinforced concrete structures /". [Hong Kong] : University of Hong Kong, 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13458917.
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Banthia, Nemkumar P. "Impact resistance of concrete". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26956.
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During its service life, a structure may be subjected to various environmental and loading conditions. However, in general, the properties determined under one set of conditions may not be used to determine the behaviour of the material under a different set of conditions. For example, it is well known that concrete is a strain rate sensitive material; therefore, its properties determined under conventional static loading cannot be used to predict the performance of concrete subjected to high strain rates. The problem is serious because these high strain rate loadings are associated with large amounts of energy imparted to the structure in a very short period of time, and concrete is a brittle material. Since the strain rate sensitivity of concrete prohibits the use of its statically determined properties in assessing its behaviour under dynamic conditions, high strain rate tests are required.
Impact tests were carried out on about 500 concrete beams. An instrumented drop weight impact machine was used. The instrumentation included strain gauges mounted in the striking end of the hammer (called 'the tup'), and also in one of the support anvils. In addition, three accelerometers were mounted along the length of the beam in order to obtain the beam response, and also to enable the inertial correction to the observed tup load to be made. Two different concrete mixes, normal strength with a compressive strength of 42 MPa, and high strength with a compressive strength of 82 MPa, were tested. The effect of two types of fibres, high modulus steel, and low modulus fibrillated polypropylene, in enhancing concrete properties was investigated. In addition, tests were also conducted on beams with conventional reinforcement. Hammer drop heights ranging from 0.15m to 2.30m were used. Static tests were conducted on companion specimens for a direct comparison with the dynamic results.
In general, it was found that concrete is a very stain rate sensitive material. Both the peak bending loads and the fracture energies were higher under dynamic conditions than under static conditions. Fibres, particularly the steel fibres, were found to significantly increase the ductility and the impact resistance of the composite. High strength concrete made with microsilica, in certain circumstances, was found to behave in a far more brittle manner than normal strength concrete.
High speed photography (at 10,000 frames per second) was used to study the propagation of cracks under impact loading. In general, the crack velocities were found to be far lower than the theoretical crack velocities. The presence of reinforcement, either in the form of fibres, or of continuous bars was found to reduce the crack velocity. A model was proposed based on a time step integration technique to evaluate the response of a beam subjected to an external impact pulse. The model was capable of predicting not only the experimentally observed non-linear behaviour of concrete under impact loading, but also the more pronounced brittle behaviour of high strength concrete.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Ho, Ching-ming Johnny, e 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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Al-lami, Karrar Ali. "Experimental Investigation of Fiber Reinforced Concrete Beams". PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2296.
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Shear strength of fiber reinforced concrete beams was studied in this research project. Three types of fibers were examined: hooked-end steel fiber, crimped-steel fiber, and crimped-monofilament polypropylene fibers. The experimental program included five beam specimens. Two of the beams were control specimens in which one was reinforced with minimum shear reinforcement according to ACI 318, while the other one did not have any shear reinforcement. Each one of the other three specimens was reinforced with one of the above mentioned fibers by 1% volumetric ratio. In addition to the beam specimens, three prisms were also made for each type fiber to determine their toughness.
The aim of this research was to investigate the following questions for medium-high concrete strength 1) to evaluate the effectiveness of each type of fibers on the shear strength, 2) to investigate the shear strength, toughness, crack patterns and near ultimate load crack width of each beam, and 3) to determine if using 1% volumetric ratio of fibers as shear reinforcement in beams would provide adequate strength and stiffness properties comparable to reinforcing steel used as minimum shear reinforcement.
The results showed that all three types of fibers increased the shear capacity of the beam specimens more than the beam reinforced with minimum shear reinforcement. Moreover, some of the fibers used could shift the type of failure from a pure shear failure to a combined flexural-shear or pure flexural failure.
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Levesque, Adam Paul. "Fire performance of reinforced concrete slabs". Link to electronic thesis, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-042806-171420/.
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Sasher, William C. "Testing, assessment and FRP strengthening of concrete T-beam bridges in Pennsylvania". Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5876.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains viii, 177 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 130-136).
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Rubin, Ariel. "Strenghtening of reinforced concrete bridge decks with carbon fiber composites". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19320.
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Olonisakin, Akinwumi Adeyemi. "Reinforced concrete slabs with partial lateral edge restraint". Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325008.
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Betaque, Andrew D. "Evaluation of software for analysis and design of reinforced concrete structures". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09192009-040235/.
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Newtson, Craig M. "Reconstruction algorithms to improve nondestructive evaluation of reinforced concrete /". Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/10114.
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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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Panagiotou, Marios. "Seismic design, testing and analysis of reinforced concrete wall buildings". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3307372.
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Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed July 22, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 241-247).
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Seljen, Andreas. "Testing of Fibre Reinforced Concrete : Shear Capacity of I-Beams". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22389.
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A series of full-scale steel fibre reinforced I-beams with varying web width has been tested in shear failure. A rectangular steel fibre reinforced beam and a conventionally reinforced I-beam have also been tested for comparison. The concrete used is a self-compacting concrete with a B45 classification. The concrete contains 1%vol (78,5kg/m3) steel fibres with end-hooks of type Dramix 3D 65/60.The load-deflection and load-shear crack opening response has been analysed for all beams and been compared with each other. A fibre count has also been conducted to investigate the influence the element size has on the fibre orientation. The results have been compared with guidelines from COIN and Model Code based on residual flexural tensile strengths from small beam tests according to NS-EN 14651. The report also gives an introduction of steel fibre reinforced concrete and design guidelines used to estimate the shear capacity.The results show that steel fibres have a significant effect on the shear capacity. All beams had more capacity than expected based on calculations made prior to testing. The ultimate shear capacity seems to be higher for I-beams than rectangular beams. A high fibre orientation factor in the longitudinal direction is found in the web in all beams, though a low representation of fibres around the tensile reinforcement. The orientation factor seems to increase with more slender elements. A good correlation between ultimate shear capacity and fibre orientation factor is not found within the range studied. However, the load at first crack seems to increase with higher longitudinal fibre orientation factor. An increase in the first crack load is also found for the SFRC beam compared to the beam with stirrups.
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Wang, Lu, e 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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Drbohlav, Martin. "Realizace rekonstrukce mostu u obce Planá". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392224.
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The part of the construction project "Reconstruction of the realization of the bridge at Planá" is elaborated. These are in particular the following: technical report for the construction tech-nological project, object time schedule of the construction, study of the implementation of the main technological stages of construction, project of the building site and implementation of the reinforced concrete structures.
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Cheng, Bei, e 程蓓. "Retrofitting of deep concrete coupling beams by laterally restrained side plates". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B45791132.
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Rafeeq, Ranj. "Torsional Strengthening of Reinforced Concrete Beams Using CFRP Composites". PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3125.
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Few decades ago, there were no guidelines for torsion design of reinforced concrete (RC) beams. Hence, many existing beams in older buildings have a lack of adequate torsional strength since they were not properly designed for torsion. One way to regain/rehabilitate adequate torsional strength is through application of externally bonded carbon fiber reinforced polymers (CFRP). To date, American Concrete Institute (ACI) code, as well as other building codes, do not have recommendations or provisions for strengthening RC beams for torsion using fiber-reinforced polymer (FRP) composites due to the inexistence of conclusive experimental and analytical data. Of the very limited works on this behavior, the majority of the focus has been devoted to experimental works. Realistic spandrel beams in a building that lack torsional strength were modelled in this research, and strengthened to examine various behaviors such as load capacity, deflection, torque, twist, crack propagation, ductility, and failure modes. For this purpose, six RC beams were tested: four reference beams and two strengthened beams were used to observe additional capacity through the use of carbon fiber-reinforced polymer (CFRP) sheets. To strengthen the beams, one layer of sheets was completely wrapped around them. Results show an additional torsional capacity of 63% and 178% relative to their respective reference beams. Through strengthening, modes of failure of the beams changed from brittle torsion-dominated failure to shear-flexure failure in both beams. The study also included crack pattern and ductility of test beams. Cracks became smaller in width and more evenly distributed across the torsion-loaded area, and torsional ductility was enhanced by 266% and 165% respectively. Flexural ductility was also greatly enhanced by more than five folds. Finally, using ACI 318-14, ACI 440.2R-02, and available formulae in the literature, the beams were analyzed and the respective values were compared.