Dissertations / Theses: 'Precast concrete'

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Ferraz, Andre Luiz Nonato. "Avaliação de retração e fluencias do concreto auto-adensavel para aplicação em elementos pre-moldados." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257677.

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Orientadores: Newton de Oliveira Pinto Junior, Monica Pinto Barbosa Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo Made available in DSpace on 2018-08-13T07:24:31Z (GMT). No. of bitstreams: 1 Ferraz_AndreLuizNonato_D.pdf: 9941000 bytes, checksum: 30542f4364161961a9bfdb7bfe736ac0 (MD5) Previous issue date: 2009 Resumo: Foram avaliados neste trabalho, teórica e experimentalmente, o comportamento reológico e mecânico do concreto auto-adensável (C.A.A.), em específico suas características frente as deformações lentas, retração e fluência, e sua aplicabilidade em peças pré-moldadas. Foram desenvolvidos duas composições de concreto de classes de resistência distintas, 35 e 55 MPa. Na etapa de dosagem foram utilizados os procedimentos do método REPETTE-MELO, onde nas pastas e argamassas, foram realizados ensaios reométricos, ensaios de fluidez e Mini-Slump, e na definição do traço do C.A.A., ensaios de controle, tais como Slump-Flow, Funil em V, caixa em L, caixa em U e tubo em U, assim como ensaios das propriedades mecânicas tais como resistência à tração, resistência à compressão, e módulo de elasticidade. A avaliação do comportamento dos concretos frente a fluência se deu nas idades de 7, 14, 28, e 56 dias, segundo a NBR 8224 (ABNT, 1983), e frente a retração de acordo com a norma MERCOSUL NM 131:9. Os resultados experimentais foram comparados com valores de concretos convencionais disponíveis na literatura. Todos os ensaios foram realizados no Laboratório CESP de Engenharia Civil, e no Laboratório de Hidrologia da UNESP em Ilha Solteira-SP. No estudo da deformação rápida, ensaios de tração na flexão foram realizados aos 28 e 56 dias. Os coeficientes de fluência foram calculados quer seja através dos valores experimentais como pela NBR 6118 e comparados entre si, apresentando boa correlação, com diferenças menores que 10% para toda as idades. A composição do concreto auto-adensável foi implantada para fins de avaliação, junto a empresa de Pré- Moldados Protendit de São José do Rio Preto-SP, onde foram moldadas vigas, em escala real, as quais apresentaram melhor acabamento e se mostraram 50% mais economicas, em relação a mão-de-obra, quando comparada com a viga de concreto convencional. Os resultados obtidos mostram que as composições de concreto auto-adensável apresentam maiores valores de retração e fluência quanto comparados com concretos convencionais de mesma resistência mecânica. O C.A.A. de resistência à compressão igual a 55 MPa apresentou menor retração e fluência básica que o C.A.A. de resistência 35 MPa. Abstract: This project analyzed, theoretically and experimentally, the mechanical and rheological behavior of the selfcompacting concrete (C.A.A.), specially its features according to slow deformation, shrinkage and creep, and its applicability in precast elements. Two compositions of concrete of different classes of resistance were developed, 35 MPa and 55 MPa. In the stage of the dosage, the procedures of the method REPETTE-MELO were used, rheometrical tests, fluidness tests and Mini-Slump were carried out on the pastes and the mortars, and control tests, such as Slump-Flow, funnel V test, box L, box U and tube U, and mechanical properties tests, such as tensile strength, compression strength and elasticity module were used to define the C.A.A. feature. The evaluation of the concrete behavior by creep happened at ages of 7, 14, 28, and 56 days, according to NBR 8224 (ABNT, 1983), and by shrinkage according to MERCOSUL NM 131:9. The experimental results were compared with values from conventional concrete available in the literature. All tests were performed at CESP Civil Engineer Laboratory, and at Hydrology Laboratory of the UNESP in Ilha Solteira-SP. In the fast deformation study, traction tests in flexion were performed at 28 and 56 days. The creep coefficients were calculated either through experimental values as by the NBR 6118 and compared each other, showing a good correlation, with differences smaller than 10% for all ages. The composition of self-compacting concrete was established for evaluation, in partnership with precast elements company Protendit of São José do Rio Preto-SP, where were shaped beams, in real scale, which showed better finishing and they showed themselves 50% more economical regarding labor, when compared with conventional concrete beam. The results reached show that the compositions of self-compacting concrete present higher values of shrinkage and creep when compared with conventional concrete of same strength. The C.A.A. that presented compression strength equal to 55 MPa showed a lower shrinkage and basic creep that C.A.A. strength of 35 MPa. Doutorado Edificações Doutor em Engenharia Civil

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Baali, Lama. "Self-consolidating concrete for precast, prestressed concrete bridge elements." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40689.

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The following thesis presents the results of four full scale beams tests as part of a research program conducted at McGill University. The purpose is to study the applicability of existing design provisions, in the American Association of State Highway and Transportation Officials (AASHTO) specifications, for the use of self-consolidating concrete (SCC) in precast pretensioned bridge girders. The test specimens had an overall length of 31 ft (9.4m) with a center-to-center span of 29 ft (8.8m). They were cast in four batches with different concrete attributes: two non air-entrained SCC mixtures and two high-performance concretes. For each type, compressive strengths of 8,000 and 10,000 psi (55.2 and 69 MPa) with release strengths of 5,000 and 6,250 psi (34.5 and 43 MPa) at 18 hours, respectively, were tested. Each girder was prestressed with eight Grade 270 seven-wire low-relaxation prestressing strands of 0.6 in (15.2 mm) diameter. Six of the strands were straight and two were harped twice, 4’-11” (1.5 m) from mid-span. The specimens were supported on neoprene bearing pads at their ends, and were tested with two equal point loads located 4’-11” (1.5 m) from mid-span. This research project demonstrated that the shear failure of the girders exceeded the predicted nominal shear resistance given by the 2004 AASHTO Specifications. The experimental flexural resistance also exceeded the predicted nominal resistance. Le présent mémoire expose les résultats de quatre poutres pleine grandeur faisant partie intégrante d’une étude effectuée à l’Université McGill. Le but de cette étude est de valider l’applicabilité des provisions de conception existantes, de l’Association Américaine des Autoroutes d’État et des Officiers de Transport (norme AASHTO), pour l’usage de béton autoplaçant (BAP) dans les poutres précontraintes et préfabriquées de ponts.Les spécimens testés ont une longueur maximale de 31 pieds (9.4 m) avec une distance du centre au centre de 29 pieds (8.8 m). Les poutres ont été coulées une à la fois avec différentes sortes de béton: deux d’entres-elles à partir de béton autoplaçant sans air entrappé, et deux avec du béton haute-performance. Pour chaque sorte, une résistance compressive de 8,000 et 10,000 psi (55.2 et 69 MPa) avec une résistance, avant de précontraindre le béton, de 5,000 et 6,250 psi (34.5 et 43 MPa) à 18 heures, respectivement, ont été testées. Chaque poutre était précontrainte avec huit tendons, grade 270, de 0.6 in (15.2 mm) de diamètre. Six de ces tendons étaient horizontaux alors que deux étaient inclinés 59 pouces (1.5 m) de chaque bord de l’axe central. Les spécimens étaient supportés aux deux extrémités sur des pads de néoprène et étaient testés avec deux charges concentriques situées 59 pouces (1.5 m) de l’axe central.Cette recherche à démontrer que la capacité en cisaillement des poutres testées excédait les valeurs nominales prévues par les normes AASHTO 2004. Les valeurs expérimentales de la résistance à la flexion des poutres aussi excèdent les valeurs nominales prédises.

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Ragupathy, Pasupathy. "Nonlinear behaviour of precast concrete frames." Thesis, City University London, 1994. http://openaccess.city.ac.uk/8380/.

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This thesis describes a new technique for studying the non-linear behaviour of reinforced concrete frames with flexible joints. The method is based on the concept of establishing an equilibrium deflected shape of a structure. The computations involve two basic levels of iteration. First, starting with an assumed nodal deformation, equilibrium deflected shapes and end forces of individual members in a structure are calculated using moment-thrust-curvature relations. The out of balance forces are computed by considering equilibrium of member forces at nodal points. In the second level of iteration based on a numerically computed nonlinear stiffness matrix, the nodal deformation are updated until the out of balance forces are negligible. The interaction of torsion with flexure has been assumed to be independent and further, the members are assumed to behave linearly in torsion. The influence of floors and cladding is ignored and only the skeleton frame is considered in the analysis. The associated computer program SWANSA based on the above method can be used as a design tool for sway and nonsway concrete frames with or without flexible joints. An interactive data entry facility allows the user to enter data by answering simple questions or by returning default values. Full scale experiments were carried out on eight column beam subframes to validate the computer program. Each subframe consisted of a two storey column with a short length of a typical mid-storey beam. Four types of connection commonly used in precast construction were selected to connect the beam to the column at mid height. Two sets of subframes were made for each connection, one each of a pair of subframes was tested for upward and downward rotations. The numerical technique is further validated with results published in literature, including experiments and the finite element method. All the comparisons show that the analysis developed in this thesis can be used to predict the behaviour of precast and other reinforced concrete frames for deflections, strains and for the ultimate loads. Finally, it is shown how a computer program based on the new numerical method can be used as an alternative method of designing rigid jointed or semi-rigid jointed precast concrete 3-dimensional frames, taking into account material and geometrical nonlinearities.

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Ronné, Phillip Dean. "The durability of precast concrete elements." Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/5007.

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Bibliography: leaves 69-72. Modern fast track construction methods increasingly favour the use of precast concrete elements. Precast box culverts are structurally significant units, subject to an important combination of bridge loadings. Culverts occasionally in contact with water pose a high durability risk. Despite this, the current specifications allow a reduction in cover to reinforcing steel for precast culverts to only 20 mm from at least 40 mm for cast-in-place culverts.

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Leung, Chun-yu Cliff, and 梁鎮宇. "Performance of in-situ concrete stitches in precast concrete segmentalbridges." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B49617758.

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Multi-span precast concrete segmental bridges are commonly constructed using the balanced cantilever method, which essentially involves sequentially extending precast segments outwards from each pier in a balanced manner. A gap of 100 to 200 mm wide is usually provided around the mid-span location between the last two approaching segments to facilitate erection. In-situ concrete is then cast to ‘stitch’ the segments together, thus making the bridge deck continuous. In the current practice, the in-situ concrete stitches are usually designed to be capable of sustaining considerable sagging moment but only minimal hogging moment. Failure of stitches may occur under exceptional circumstances that may potentially trigger a progressive collapse. However, relatively little research in this area has been carried out. In view of this, the author is motivated to undertake an extensive study of the behaviour of in-situ concrete stitches and the effects of their performance on the robustness of typical segmental bridges. Experimental study is carried out to examine the behaviour of in-situ stitches under different combinations of internal forces. Series of stitch specimens of different configurations are tested. Subsequent parametric studies are conducted numerically to examine the effects of various parameters on the load-displacement characteristics of the stitches. Formulae for strength estimation are proposed based on the results. A study of robustness involves analyzing the collapse behaviour of a structure in an extreme event and the analysis should be carried out up to and then well beyond the state of peak strength of structural members. A finite element programme for post-peak analysis is therefore developed for the present study. As the ability of a member section to sustain large inelastic deformation can ultimately affect the robustness of a structure, an investigation is conducted to examine the effects of steel content, yield strength and prestressing level on the ductility and deformability of prestressed concrete sections. Using the programme developed, the formation of collapsing mechanisms of a multi-span segmental bridge deck in an extreme event is examined. A typical bridge deck is subject to prescribed accidental load on its span in order to analyze the sequence of failure. Substantial redistribution of internal forces along the deck is observed as failures initiate, thus causing subsequent failures of other deck sections even though they have been designed to resist the internal forces at the ultimate limit state. The results indicate that any span of a multispan bridge may become a temporary end-span in the event of collapse of an adjacent span and the strength of the sections must be designed accordingly to prevent progressive failure. As a span becomes a temporary end-span, the in-situ concrete stitches may experience substantial moment and shear, and their failure could potentially trigger progressive collapse of the entire bridge deck. Towards the end of the thesis, important design considerations that can enhance the performance of in-situ concrete stitches and robustness of precast concrete segmental bridges are presented. published_or_final_version Civil Engineering Doctoral Doctor of Philosophy

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Matsumoto, Eric Eiji. "Development of a precast bent cap system /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004334.

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Joy, Westin T. "Concrete capacity design of the Cazaly hanger." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1799711381&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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Bristowe, Stuart J. (Stuart James). "Seismic response of precast concrete wall panels." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22641.

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Precast concrete structures are not widely used in severe seismic regions due the limited knowledge of the response of these systems to reversed cyclic loading. A series of four precast concrete wall panels were tested to evaluate their response to reversed cyclic loading. These units represent the wall panels of a typical single storey precast concrete structure. In order to achieve improved ductility and energy absorption characteristic, it was found that the horizontal sliding of the wall panel along the grout-wall interface must be controlled. Due to the reversed cyclic loading and the increased wall panel participation from limiting the horizontal sliding of the wall, it was determined that shear reinforcement of each precast specimen was separated into three separate component parts, joint rotation, wall panel deformations and horizontal wall panel sliding, to compare and evaluate the seismic performance of the wall panels.

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Herlihy, Michael D. "Precast concrete floor support and diaphragm action." Thesis, University of Canterbury. Engineering, 1999. http://hdl.handle.net/10092/9578.

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Experimental research, engineering analysis and theoretical developments comprise a study in which various interactions between ductile moment resisting frames and precast prestressed hollow core flooring have been examined. The most critical interaction tested involves support behaviour, and the ability of reinforcing details to provide control against loss of support and possible catastrophic flooring collapse under dilation effects. Plastic hinge dilation, also known as elongation or growth, is an inherent property of ductile concrete members when subjected to cyclic plastic deformations. Hence, the performance of floor support details is enveloped by the general design philosophy of seismic resisting structures. In the experimental phase, emphasis was placed on testing support construction joints from contemporary building practice, for direct comparison with special support tie details of known capabilities. The contemporary details were found to exhibit seriously flawed behaviour under monotonic and cyclic loading regimes. Corroborative experiments were undertaken to establish direct shear capacities between typical composite bond surfaces. In particular, these tests addressed the discrepancy that has emerged between direct shear and shear flow strengths. Also, the continuity response of conventional and proposed support detail types was examined. A composite section model was analysed to demonstrate the likely influence of prestressing steel on beam bending strength within a ductile frame environment. Likewise, the probable effects of prestressing steel on beam plastic hinge development were examined, but on a more theoretical basis. Other elements of theory have been presented. These mainly concern the general topic of elastic-plastic response in reinforced concrete elements. The particular focus of this work has been to demonstrate a rational basis to stiffness transition and plastic buckling analysis. The important role of stiffness degradation in dynamic analysis has also been examined. Although ductile moment resisting concrete frames have been emphasised, it is considered that the findings of this thesis are applicable to other structural systems, such as dry joint "hybrid" precast concrete frames and spring connected steel frame structures.

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Baird, Andrew. "Seismic performance of precast concrete cladding systems." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2014. http://hdl.handle.net/10092/9997.

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Structural engineering is facing an extraordinarily challenging era. These challenges are driven by the increasing expectations of modern society to provide low-cost, architecturally appealing structures which can withstand large earthquakes. However, being able to avoid collapse in a large earthquake is no longer enough. A building must now be able to withstand a major seismic event with negligible damage so that it is immediately occupiable following such an event. As recent earthquakes have shown, the economic consequences of not achieving this level of performance are not acceptable. Technological solutions for low-damage structural systems are emerging. However, the goal of developing a low-damage building requires improving the performance of both the structural skeleton and the non-structural components. These non-structural components include items such as the claddings, partitions, ceilings and contents. Previous research has shown that damage to such items contributes a disproportionate amount to the overall economic losses in an earthquake. One such non-structural element that has a history of poor performance is the external cladding system, and this forms the focus of this research. Cladding systems are invariably complicated and provide a number of architectural functions. Therefore, it is important than when seeking to improve their seismic performance that these functions are not neglected. The seismic vulnerability of cladding systems are determined in this research through a desktop background study, literature review, and postearthquake reconnaissance survey of their performance in the 2010 – 2011 Canterbury earthquake sequence. This study identified that precast concrete claddings present a significant life-safety risk to pedestrians, and that the effect they have upon the primary structure is not well understood. The main objective of this research is consequently to better understand the performance of precast concrete cladding systems in earthquakes. This is achieved through an experimental campaign and numerical modelling of a range of precast concrete cladding systems. The experimental campaign consists of uni-directional, quasi static cyclic earthquake simulation on a test frame which represents a single-storey, single-bay portion of a reinforced concrete building. The test frame is clad with various precast concrete cladding panel configurations. A major focus is placed upon the influence the connection between the cladding panel and structural frame has upon seismic performance. A combination of experimental component testing, finite element modelling and analytical derivation is used to develop cladding models of the cladding systems investigated. The cyclic responses of the models are compared with the experimental data to evaluate their accuracy and validity. The comparison shows that the cladding models developed provide an excellent representation of real-world cladding behaviour. The cladding models are subsequently applied to a ten-storey case-study building. The expected seismic performance is examined with and without the cladding taken into consideration. The numerical analyses of the case-study building include modal analyses, nonlinear adaptive pushover analyses, and non-linear dynamic seismic response (time history) analyses to different levels of seismic hazard. The clad frame models are compared to the bare frame model to investigate the effect the cladding has upon the structural behaviour. Both the structural performance and cladding performance are also assessed using qualitative damage states. The results show a poor performance of precast concrete cladding systems is expected when traditional connection typologies are used. This result confirms the misalignment of structural and cladding damage observed in recent earthquake events. Consequently, this research explores the potential of an innovative cladding connection. The outcomes from this research shows that the innovative cladding connection proposed here is able to achieve low-damage performance whilst also being cost comparable to a traditional cladding connection. It is also theoretically possible that the connection can provide a positive value to the seismic performance of the structure by adding addition strength, stiffness and damping. Finally, the losses associated with both the traditional and innovative cladding systems are compared in terms of tangible outcomes, namely: repair costs, repair time and casualties. The results confirm that the use of innovative cladding technology can substantially reduce the overall losses that result from cladding damage.

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Omar, Wahid. "Diaphragm action in precast concrete floor construction." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254392.

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Salmo, Salim Hanna. "Precast concrete pavements used in port areas." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315673.

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Robinson, Gary P. "Design and performance of precast concrete structures." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14722.

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A precast concrete structural system offers many advantages over in-situ casting. For example, greater control over the quality of materials and workmanship, improved health and safety (with casting carried out at ground level rather than at height) and cost efficiency (with standard forms continually re-used) are all realised through the off-site production of structural elements. As a result, a large body of research has been conducted into their performance, with many national codes of practice also devoting specific sections to design and detailing. However, contemporary design practice has been shown to not always correctly reflect the findings of published experimental studies. Concrete technology is continually evolving, as is the industry s knowledge of how to model and predict the behaviour of the resulting structural components. Using such understanding to design and justify the more efficient, cost-effective or flexible manufacture of precast components can offer a key commercial advantage to a precast manufacturer. In this context, the numerical and experimental investigations undertaken as part of this study have been specifically focussed on quantifying the advantages of utilising beneficial alternatives. Specifically the research has looked at improvements in concrete mixes, lightweight aggregates and reinforcing strategies, for precast structural elements required to transfer loads both vertically and horizontally. However, because of the non-standard solutions considered, different approaches have been used to demonstrate their suitability. Towards this goal, an alternative assessment strategy was devised for slender precast concrete panels with central reinforcement. The procedure was found to lead to design capacities that are in good agreement with actual experimental findings and should thus result in future manufacturing efficiency. The method can also be used for alternative concrete types and reinforcement layouts. Fresh and early-age material characteristics of self-compacting concrete mixes with a partial or complete replacement of traditional gravel and sand constituents with lightweight alternatives were investigated. This was done to demonstrate the feasibility of their use for the manufacture of large scale structural components, with clear benefits in terms of lifting and transportation. A computational push-down procedure was utilised to demonstrate the potential unsuitability of current tying regulations for avoiding a progressive collapse event in precast framed structures. The findings are considered to be of particular significance for these structures due to the segmental nature of the construction and the associated inherent lack of structural continuity.

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Oskarsson, Adam. "Transmission of Vibrations in Precast Concrete Slabs." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79119.

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Dynamic loads have historically not been a troubled area for concrete ﬂoors, foremostbecause of the high self-weight compared to the dynamic load. With new technical andcalculation achievements during the last decades concrete ﬂoors have become longerand more slender. This have led to more open plan structures with longer spans thatmake concrete ﬂoors more sensitive to vibrations.This thesis studies the dynamic eﬀects of hollow concrete core elements induced by co-ordinated jumping and the vibration levels that spread to the ﬂoor above. The thesisinvestigates diﬀerent standards and guides on how to perform a dynamic analysis andevaluate it. In the thesis an experiment was conducted on WSP Sweden headquar-ters in Stockholm. The ﬁfth and sixth ﬂoor of the building was investigated in thisthesis. The ﬂoors are made of hollow concrete core elements of the type HD/F 120/27.First a so-called heel drop test was done on the ﬁfth ﬂoor to evaluate the naturalfrequency of the ﬂoor. The ﬂoors were monitored while 12 people performed coordi-nated jumping. Three accelerometers were placed on the ﬁfth ﬂoor where the load wasapplied and one on the ﬂoor above.The results from the experiment and simulation were evaluated with three methodsISO 10137, National Building Code of Canada and Design Guide - Floor VibrationsDue to Human Activity. The data from the experiment shows that the upper ﬂoor isunsuitable for oﬃce use for 2 standards. The lower ﬂoor is viewed as acceptable formore carefree setting such as shopping malls.A ﬁnite element analysis of the building was done in the program Brigade. The modelconsists of one wing of the building and the ﬁfth and sixth ﬂoor. The remaining ﬂoorsare modelled as equivalent mass. The columns were modeled down to the fourth ﬂoorand the beams for the ﬁfth and six ﬂoors were included. A stairwell between the ﬁfthand sixth ﬂoor was also modelledEvaluation of the ﬁnite element results was done in the same fashion as the experi-ment. Here the upper ﬂoor was performing satisfactory for oﬃce use and the lowerﬂoor was similarly as the experiment above accepted for settings where more acceler-ation is considered acceptable such as for restaurants and shopping malls.The maximum transient vibration value (MTVV) results from the experiment andsimulation was compared and the lower ﬂoor was conforming pretty well with a dif-ference smaller than 1 % to around 30 % depending on the accelerometer. However,the results for the upper ﬂoor diﬀers signiﬁcantly, as the diﬀerence is about 770 %between the experiment and simulation. The ﬁnite element model is not able to ac-curately represent the real building for the acceleration of the upper ﬂoor. This couldbe explained by the the absence of partition walls for meeting rooms, copying room,toilets and the facade. Since this could limit the acceleration that is transmitted fromthe lower ﬂoor to the upper ﬂoor.

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Cojocaru, Razvan. "Lifting Analysis of Precast Prestressed Concrete Beams." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/32464.

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Motivated by Robert Mastâ s original papers on lifting stability, this research study provides a method for predicting beam behavior during lifting, with application in the construction of bridges. A beam lifting cracking limit state is developed based on analytical equations for calculating the roll angle of the beam, the internal forces and moments, the weak-axis and strong-axis deflections, and the cross-sectional angle of twist. Finite element simulations are performed to investigate the behavior of concrete beams during lifting and to validate the proposed method. Additionally, a statistical characterization of beam imperfections is presented, based on recently conducted field measurements of beam lateral sweep and eccentricity of lift supports. Finally, numerical examples for two typical precast prestressed concrete beam cross-sections are included to demonstrate the proposed method. Master of Science

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Champney, Mark Allen. "Development of high performance concrete for precast prestressed bridges." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/22971.

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Susoy, Melih. "Seismic Strengthening Of Masonry Infilled Reinforced Concrete Frames With Precast Concrete Panels." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605563/index.pdf.

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Over 90% of the land area of Turkey lies over one of the most active seismic zones in the world. Hazardous earthquakes frequently occur and cause heavy damage to the economy of the country as well as human lives. Unfortunately, the majority of buildings in Turkey do not have enough seismic resistance capacity. The most commonly observed problems are faulty system configuration, insufficient lateral stiffness, improper detailing, poor material quality and mistakes during construction. Strengthening of R/C framed structures by using cast-in-place R/C infills leads to a huge construction work and is time consuming. On the other hand, using prefabricated panel infills can be preferred as a more feasible, rapid and easy technique during which the structure can remain operational. The aim of this experimental study is to observe the seismic behavior of R/C frames strengthened by precast concrete panel infills by testing different types of panel and connection designs in eight single-story single-bay reinforced concrete frame specimens.

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Peng, Brian Hsuan-Hsien. "Seismic performance assessment of reinforced concrete buildings with precast concrete floor systems." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2009. http://hdl.handle.net/10092/3103.

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In the seismic design of reinforced concrete frames, plastic hinges are allocated to beams such that a ductile beam-sway mechanism will form in preference to other less ductile mechanisms in the event of a major earthquake. This is achieved by ensuring that the flexural strength of columns is greater than that corresponding to the maximum likely flexural strength of beam plastic hinges. Recent experimental studies in New Zealand have shown that elongation of ductile beam plastic hinges, and its interaction with nearby floor slab containing precast-prestressed floor units, increases the strength of beams much more than that specified in New Zealand and American Concrete standards. This level of strength enhancement has raised concern on the adequacy of the current design provisions. To further investigate this problem, a research project was initiated to examine the strength of beam plastic hinges in reinforced concrete frames containing precast-prestressed floor units. In this research, the strength of beam plastic hinges was assessed through experimental and analytical studies. A three-dimensional, one-storey, two-bay reinforced concrete moment resisting frame with prestressed floor units and cast-in-situ concrete topping was tested under quasi-static displacement-controlled cyclic loading. The experimental results provided insight into the mechanics associated with frame-floor interaction. Subsequently, improved design specifications were proposed based on the observed behaviour. To analytically predict the beam-floor interaction, a ductile reinforced concrete plastic hinge multi-spring element was developed and validated with experimental results from cantilever beam and frame sub-assembly tests reported in the literature. The comparisons have demonstrated the ability of the proposed plastic hinge element to predict the flexural, shear, axial, and most importantly, elongation response of ductile plastic hinges. The proposed plastic hinge element was implemented into an analytical model to simulate the behaviour of the frame-floor sub-assembly tested in this research. Specially arranged truss-like elements were used to model the linking slab (the region connecting the main beam to the first prestressed floor unit), where significant inelastic behaviour was expected to occur. The analytical model was found to be capable of predicting the non-linear hysteretic response and the main deformation mechanisms in the frame-floor sub-assembly test. The analytical frame-floor model developed in this study was used to examine the effect of different structural arrangements on the cyclic behaviour of frames containing prestressed floor units. These analyses indicated that slab reinforcement content, the number of bays in a frame and the position of frame in a building (i.e., perimeter or internal frame) can have a significant influence on the strength and elongation response of plastic hinges.

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Arnau, Delgado Oriol. "Structural response of precast concrete segmental tunnel linings." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/81563.

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The increasing use of the tunnel boring machines (TBMs) has entailed their own evolution and the improvement of the construction processes applied, allowing the construction of tunnels on more complex hydro-geological conditions. These new drilling facilities imply that higher ground and water pressures have to be resisted by the structural lining, turning its design into a key item in all current tunnel projects. TBMs construction process is mainly associated to precast concrete segmental tunnel linings, which are consisted of concrete rings sequentially placed as the tunnel drilling advances. Despite segmental tunnel linings are widely used, their structural response presents significant uncertainties due to the particular configuration on multiple precast pieces and the evolutionary construction process applied. The improvement and optimization of segmental tunnel linings, necessary to obtain safer structures at a lower cost, requires a significant advance in the knowledge of their structural response and about the appropriate techniques to properly reproduce it. This PhD thesis present the mechanisms and phenomena involved in the structural response of precast concrete segmental tunnel linings, detailing numerical modeling strategies to properly simulate them. The integration of all these techniques in a unique model allows the analysis of a real tunnel lining subjected to different scenarios, determining the influence and relevance of the main parameters defining a tunnel and its structural lining. Present research departs from an innovative in situ test carried out at Line 9 subway tunnel in Barcelona. The treatment and analysis of the obtained data provides experimental evidences about the structural response of segmental tunnel linings and the main involved mechanisms and phenomena. Different numerical simulation strategies are developed in order to properly reproduce such mechanism and phenomena, achieving a reliable simulation of an isolated ring response. The longitudinal response of the segmental concrete linings is obtained through the detailed study of the construction process applied and the ground-structure interaction mechanisms. The knowledge of the longitudinal force present at a segmental tunnel lining is of paramount importance in order to determine the interaction degree between adjacent rings and the consequent three-dimensionality of the lining response. Finally, the numerical simulation of a real tunnel section subjected to different scenarios of load and boundary conditions determines the influence of the three-dimensional effects on segmental concrete linings response, concluding about its structural implications in respect to the isolated ring approach usually employed in design processes.

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20

Hasan, Sarakot. "Behaviour of discontinuous precast concrete beam-column connections." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12269/.

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The study investigates experimentally and theoretically the behaviour of an internal precast concrete beam-column connection, where both the column and beam are discontinuous in construction terms. The aim was to modify the behaviour mechanisms within the connection zone by introducing a beam hogging moment resistance capacity under dead loads and limiting the damage within the connection. This is to offer permanent dead load hogging moments that could counterbalance any temporary sagging moment generated under sway loads, enhance the rotational stiffness, balance the design requirements for the beam-end and beam mid-span moments, provide efficient continuity across the column, and reduce the deflection at the beam mid-span. Three full-scale beam-column connection tests subjected to gravity loads were conducted taking the connection reinforcement detail as the main variable. The configuration of the three main interfaces within the connection was based on the experimental results of small-scale tests. The results of the full-scale tests showed that, by using the strong connection concept, it was possible to produce equivalent monolithic behaviour, control the crack width within the connection zone, and force the final damage to occur outside of this zone, which comprises the interfaces and parts of the adjoining elements. The strong connection consisted of using additional short steel bars crossing the connection at the top of the beam, horizontal U-shaped links at the beam-ends, and additional column links. In addition, the experimental programme included two full-scale tests to investigate the behaviour of the connection under sway loads using two different connection reinforcement details. The results of this study showed that the proposed modification in the reinforcement details was able to mobilise the beam sagging moment through the dowel action of the column main bars but it was also accompanied by large relative beam-column rotations (low rotational stiffness). The evaluation of the behaviour of the connections was carried out by incorporating the experimental rotational stiffnesses in semi-rigid frame analyses using the ANSYS software package and a Visual Basic program based on the conventional semi-rigid analysis approach. In addition, a simplified technique has been validated against these two methods to replicate the semi-rigid behaviour. In the same respect, the study is proposing a new approach for classifying precast concrete beam-column connections as rigid by relating the connection fixity factor with the moment redistribution. It has been shown that the connection could be classified as rigid if the fixity factor is not less than 0.73 and the available moment redistribution from the midspan to the supports is not less than the required moment redistribution resulting from semi-rigid frame analysis. In the theoretical part, an analytical tool has been calibrated to predict the rotational stiffness of the specimens with semi-rigid behaviour under gravity loads. The model showed a reasonable agreement with the experimental results. To help the modelling, two pull-out tests were conducted to determine the bond-slip relation of steel bars embedded in cement-based grout. Moreover, a finite element numerical simulation model using the ANSYS software package was carried out to replicate the experimental results of the semi-rigid specimens tested under gravity loads. In spite of providing results close to experimental values prior to yielding, the FE model was not able to predict the failure mode and consequently the correct ultimate load. This is due to the simplified way of modelling the interaction between the corrugated sleeves and the surrounding concrete as perfect bond. The research concludes that the precast beam-column connection investigated in the current study can be treated as an emulative monolithic connection under gravity loads through using the strong connection concept; however, it is not suitable to resist beam net sagging moments. Besides, the study concludes that to consider a precast concrete beam-column connection as rigid, it is required to correlate the fixity factor with the moment redistribution.

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21

Restrepo-Posada, José I. "Seismic behaviour of connections between precast concrete elements." Thesis, University of Canterbury. Civil Engineering, 1992. http://hdl.handle.net/10092/7666.

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Several precast concrete systems have been in use in New Zealand in the construction of moment resisting frames designed for earthquake resistance, despite the lack of code design guidelines. The two design codes for buildings, NZS 4203 (1984) and NZS 3101 (1982), deal only with the design of monolithic concrete construction. The use of precast concrete in moment resisting frames in New Zealand assumes that this method of construction behaves the same as monolithic reinforced concrete structures. A test programme was devised to provided experimental evidence on the seismic behaviour of the most commonly used precast concrete arrangements. Six full-scale subassemblages were quasi-statically tested under reverse load conditions with increasing displacements to failure. Four tests were conducted in H-shaped specimens connected at the beam midspan. The remaining two specimens were cruciform-shaped and had the connection detail in the critical region at the beam-column joint. It was found that neither of the connection detail nor the construction joints have a detrimental effect on the seismic performance. Hence, the assumption of designing these systems as if monolithic is adequate. Theoretical work was undertaken to give simple design recommendations for the design of different connecting details, including the design of interior beam-column joints. Truss models and the concept of shear friction were extensively used. This report also discusses in some detail the stress-strain behaviour of the two grades of New Zealand manufactured reinforcing steel. Test results on the effects of bar deformations, strain ageing and strain rate on the cyclic behaviour of reinforcing steel are presented. An analytical model based on test results is postulated

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22

Lim, Linus C. S. "Stability of Precast Concrete Tilt Panels in Fire." University of Canterbury. Civil Engineering, 2000. http://hdl.handle.net/10092/8280.

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This report investigates the behaviour of slender cantilever concrete panels and concrete panels in steel frames exposed to elevated temperatures. This report also provides recommendations for the design of slender tilt-up wall panels for fire resistance. The current trend of tilt-up construction in industrial buildings utilises very tall and thin concrete wall panels that are reinforced with a single layer of reinforcing in the middle. These wall panels are cantilevered from the base and are not connected to a column or a portal frame. The panels are connected directly to the steel frame by a steel rafter or indirectly to the eaves tie. The analysis of this project was conducted using SAFIR, a non-linear finite element programme developed in the University of Liege, Belgium. Reinforced concrete walls subjected to a fire on one side will undergo non-uniform thermal expansion, causing the walls to bow. Free-standing concrete cantilever walls with slenderness ratios (Height to thickness ratio) in excess of 50 experience very large deflections when exposed to a fire on one side. The analyses have shown that these large deflections will lead to outward collapse of the walls onto the neighbouring property. Concrete cantilever walls connected to unbraced steel frames are dangerous as they cause the frame to sway and fall out onto the neighbouring property during a fire. Braced steel frames connected to the walls enhance the behaviour of the walls by preventing the large outward deflections of the panels. If bracing is available from the steel roof to prevent sway, the wall panels can be constructed up to 12 metres and slenderness ratios up to 96, without outward collapse or buckling failure of the wall panels. For the partially braced frames conducted in this study, the height of the wall panels should not exceed 9.0 metres and the slenderness ratios should not exceed 65. It is concluded that the deflections of the free standing cantilever walls should be controlled. Slender cantilever walls should be connected to a braced steel frame with well designed connections to the rafter and the eaves tie.

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23

Luheshi, Yousef Bashir. "The fatigue characteristics of precast concrete raft units." Thesis, University of Newcastle Upon Tyne, 1997. http://hdl.handle.net/10443/1582.

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This research project represents a continuation of the research programme into Precast Concrete Pavement Units, "P. C. P. U. ", which is based in the Department of Civil Engineering at the University of Newcastle upon Tyne. The units were referred to as raft units throughout the thesis which focused on the use of raft units as a full concrete paving system for aircraft parking, taxiway, and other low speed areas, at airports. The physical full scale test model was designed and constructed to represent the applied loading from one of the dual wheel legs of the design aircraft, a Boeing 727-200, when it is taxiing over a raft unit paving system. It was only possible for the test model to be provided with a contact area of 200 mm square compared to the real life of 400 mm square. A theoretical correction was applied to allow for this difference. Sixteen raft units were tested in pairs using the test model. The tests were divided into three modules to investigate the effect of the raft unit dimensions, Module(M1); the reinforcement design, Module(M2); and the raft thickness, Module(M3). The twin loading assembly applied a repetitive dynamic load which was moved manually between four different loading positions to represent the aircraft moving across the raft units. The primary aim of the experimental programme was to identify for the first time the fatigue life and failure mechanisms of the raft units under the influence of twin dynamic moving loads, and provide experimental results to enable a more refined numerical design method to emerge for raft units, as well as to determine the causes of failures and to recommend remedial measures. Observations were made of vertical deflection, concrete strains, crack widths and crack patterns, failure load, and failure modes, each of which were described in detail. The test observations showed that by increasing each of the following variables, namely, the aspect ratio, the amount of steel bar reinforcement and the thickness of the raft units, resulted in each case in an extension of raft unit life. It was found that some form of uplift restraint on the raft unit should be added to improve the fatigue life for one of the loading positions and that fibre reinforcement should not be used. The ultimate load capacity of the raft units was influenced by the loading position, the applied load level and the number of load repetitions, together with the crack patterns. Using the results from the raft units that had failed within a specific module, it was possible to predict the ultimate and reserve load capacity of raft units within the modules that were only partially fatigued. Four important conclusions have been established during the research project. Firstly, based on the test results, an empirical relationship was derived using regression analysis, relating the number of load repetitions to the aspect ratio, the amount of reinforcement, the raft thickness, and the applied loading. This will need further verification, but it should eventually be very useful when estimating the fatigue life of these specific raft unit models. Secondly, a new design method has been proposed. The design methods for raft units proposed previously by Bull, Ismail, Annang, Ackroyd, and the British Port Association were reviewed. The test results enabled a new design method to be developed which was based on Bull's method but proposed new design charts and tables for each of the raft units considered in the research project which introduced the additional variables of contact pressure and the exact loading position. Thirdly, the measured strains were used to develop strain fatigue relationships for designing raft units and estimating the reserve design life in a raft unit paving system for the purpose of maintenance management by relating the accumulated number of load repetitions of a design load to the permissible concrete strain. The strain fatigue equations were generated for each of the raft units considered in this research project. Thus, the most realistic way to control raft unit distress is through the use of a predictive fatigue model. This should prove invaluable to those involved in the maintenance of raft unit paving systems. Finally, life cycle cost analysis was conducted for three types of construction pavement (paving blocks, PQC, and raft units). The analysis demonstrated that the precast concrete raft units will become a viable alternative to conventional pavement construction and a real competitive to the concrete paving blocks.

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Al-Tamimi, Adnan. "Fibre-reinforced connections in precast concrete flat slabs." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367112.

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25

Dunbeck, Jennifer. "Evaluation of high strength lightweight concrete precast, prestressed bridge girders." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28091.

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26

Sun, Minhui. "A study of precast reinforced concrete skeleton for low-cost housing /." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61221.

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This thesis is a survey of the precast reinforced concrete skeleton system used in low-cost housing (SPCSS), which has widely spread to different areas of the world, but less studied. The thesis includes three major parts: (1) the development of SPCSS; (2) the design, performance feature of SPCSS; and (3) cases studies. The development of SPCSS traces its origin as the structure of prefabricated houses for the housing shortage after the world war in Europe to its spread to developing countries for low-cost housing. Design and performance study focuses on its features related to low-cost housing its special considerations and key points in design as a small component system, its acclaimed system performance features. Case studies surveys 15 typical cases. Each case includes general background of the system, system design, comments following the design consideration and example of its application.

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27

Morshed, Md Abu. "Early carbonation curing of fresh concrete and its applications in precast concrete production." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117115.

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Carbonation curing of fresh concrete at early age and the feasibility to integrate the technology into precast concrete production were investigated. It was found that equilibrium of relative humidity between ambient environment and interior concretes was not possible to achieve in early carbonation of fresh concrete even with preconditioning. Instead, the degree of carbonation was dominated more by the water content in the concrete than by its internal humidity. A fan-drying precondition seemed to be necessary and practically feasible to justify the water content in industry scale application. The process was applied to the production of precast lightweight concrete panels and normal weight hollow core concrete slabs. The lightweight aggregates were utilized as internal water reservoirs to balance the moisture equilibrium during preconditioning, carbonation reaction and subsequent hydration. Water movement from the internal reservoirs was postulated by resistivity measurements; and was further verified in terms of CO2 uptake, strength development, plastic shrinkage compensation and alkalinity regain. A near-surface diffusion carbonation curing was developed to partially replace the heat curing in hollow-core concrete slab production. The hollow core slab so produced had shown much better strength than the hydration reference or by the heat curing alone, with reduced porosity and less vulnerability to delayed ettringite formation. Besides the technical benefits, CO2 sequestration potential is an added value to the process. An average 15% CO2 uptake could lead to sequestration of approximately 10,000 tonnes of CO2 per year by precast hollow-core concrete plants in Canada alone. La carbonatation du béton frais effectuée à son plus jeune âge, ainsi que la possibilité de potentiellement intégrer cette technologie dans la production du béton préfabriqué a été analysé dans cette étude. Il a été constaté que l'équilibre de l'humidité relative entre l'intérieur du béton et le milieu ambiant dans lequel il se trouve n'était pas possible à établir au début du processus préalable de la cure du béton frais par carbonatation. De plus, la quantité d'eau présente affecte le degré de carbonatation bien plus que l'humidité relative interne. Le séchage préalable du béton par ventilateurs d'es trouvé nécessaire et pratique afin de justifier la présence d'eau à l'échelle industrielle. Le processus a été utilisé pour la production des panneaux de béton préfabriqué de poids léger, ainsi que pour les dalles de béton alvéolées de poids ordinaire. L'utilisation des granulats légers en tant que réservoirs d'eau internes a servi à balancer l'humidité d'équilibre durant le déroulement de tout le processus, voir du début de l'étape préalable, durant la période de carbonatation jusqu'à l'hydratation postérieure. La circulation d'eau des réservoirs internes est due aux mesures de résistivité; ceci a été validé en termes de l'étendu de carbonatation, du développement de la résistance mécanique, par la compensation du rétrécissement plastique, et par le regain de l'alcalinité. De plus, la carbonatation dynamique près de la surface du béton a été conçue afin de partiellement remplacer le procédé d'étuvage compris dans la production de dalles de bétons alvéolées. Ce type de dalles a démontré un bien meilleur niveau de résistance mécanique que celui atteint par les dalles ordinairement hydratées ou par les dalles étuvées. En plus d'avoir une meilleure résistance, ces dalles possèdent moins de porosité et sont moins vulnérables au développement tardif d'ettringite. Outre les avantages techniques, la possibilité de séquestration du CO2 est un gain ajouté au procédé. En moyenne, un contenu de 15% de CO2 dans la production Canadienne des dalles de bétons alvéolées pourrait séquestrer 10,000 tonnes de CO2 chaque année.

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Dailey, Cody L. "Instrumentation and early performance of an innovative prestressed precast pavement system." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4612.

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Thesis (M.S.) University of Missouri-Columbia, 2006. The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 22, 2007) Includes bibliographical references.

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29

Davis, Brent M. "Evaluation of prestress losses in an innovative prestressed precast pavement system." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4516.

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Thesis (M.S.) University of Missouri-Columbia, 2006. The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 22, 2007) Includes bibliographical references.

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30

Igwemezie, Jude O. "Dynamic response and impact effects in precast, prestressed concrete bridge ties." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74056.

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31

Mostert, Louwrens Hubert. "Design and construction preferences for connections in the precast concrete industry of South Africa." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96036.

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Thesis (MEng)--Stellenbosch University, 2014. ENGLISH ABSTRACT: Precast concrete has been used for decades in the construction industry, locally as well as internationally. Rapid urban development and the need for shorter construction periods for building and infrastructure projects have however encouraged more use of precast concrete construction. The improved speed of construction, high quality and less labour requirements that precast offers makes it an effective type of construction method for modern development. The utilization of various precast concrete systems has been frequently used in the international construction industry, making it a very popular construction method. It was however found that one of the major drawbacks or concerns with the use of precast concrete is the connections between the precast elements. In-situ construction does not have this problem, because it is designed to a monolithic structure or building. It was identified that if the connections in precast buildings or structures are designed or constructed in an insufficient way, it can lead to severe structural problems and even failure. This highlights the importance the design and construction of precast concrete connections have on the overall stability, strength and robustness of the structure. Precast concrete buildings are not merely separate precast elements, connected together to eventually form the same principals of in-situ construction. Precast concrete and connection design is considered to be a specialist field and requires the sufficient expertise and knowledge to understand the structural system and all its different aspects. The precast connection’s function is not merely to transfer loads, but also to develop continuity and ensure monolithic behaviour of the entire precast concrete structure (Englekirk 2003). The most important or desirable structural functions of precast connections are; (i) direct transfer of loads (load paths and flow or forces), (ii) develop structural continuity and integrity, (iii) distribution of concentrated loads, (iv) allow for movements and unintended restraints and lastly to (v) ensure efficient rigidity and robustness for the connection. It can be seen that there is many factors that contribute to the overall design and construction phases of precast concrete connections. The aim of this study is to identify and investigate aspects that influence the design and construction of precast concrete connections. This study will mainly focus on precast concrete and precast connection preferences of participants in the South African construction industry. During this study, industry participants (contractors and consultants) were asked to identify certain aspects and concerns associated with precast concrete and precast connection construction. These answers were used to develop guidelines and preferences that can be used by industry participants to improvise and effectively manage the precast construction, mainly focussing on the connections between the precast elements. AFRIKAANSE OPSOMMING: Voorafvervaardigde beton word al vir dekades gebruik in die konstruksiebedryf, plaaslik sowel as internasionaal. Vinnige stedelike ontwikkeling en die behoefte vir korter konstruksie tydperke vir die struktuur en infrastruktuur projekte het egter die gebruik en implementasie van voorafvervaardigde beton konstruksie laat toeneem. Die verbeterde spoed van die konstruksie proses, 'n hoë gehalte produk en minder arbeid vereistes wat voorafvervaardiging bied maak dit dus 'n effektiewe tipe konstruksie metode vir moderne ontwikkelings. Die benutting van verskeie voorafvervaardigde beton sisteme en elemente word reeds herhaaldelik gebruik in die internasionale konstruksiebedryf, wat dit vervolglik ŉ baie populêre en effektiewe sisteem maak. Dit is egter bevind dat een van die groot struikelblokke of probleme met die gebruik van voorafvervaardigde beton is die verbindings tussen die voorafvervaardigde elemente. In-situ beton konstruksie het dus nie hierdie probleem nie, want dit word ontwerp om 'n monolitiese beton struktuur of gebou te vorm. Dit was immers geïdentifiseer dat as die verbindings in ŉ voorafvervaardigde gebou of struktuur, ontwerp word deur ŉ ontoereikende manier, dit kan lei tot ernstige strukturele probleme en selfs strukturele faling. Dit beklemtoon dus die belangrikheid wat die ontwerp en konstruksie proses van voorafvervaardigde beton verbindings het op die algehele stabiliteit, sterkte en robuustheid van die struktuur. Voorafvervaardigde beton geboue en strukture kan nie slegs beskou word as aparte voorafvervaardigde elemente wat met mekaar verbind word om eventueel dieselfde beginsels van insitu konstruksie te vorm nie. Voorafvervaardigde beton en verbinding ontwerp word beskou as 'n spesialis veld en vereis dat die ontwerper die nodige kundigheid en kennis van die strukturele stelsel en al sy verskillende aspekte verstaan. Voorafvervaardigde beton verbindings se funksie is nie net om toegepaste kragte oor te dra nie, maar ook om strukturele kontinuïteit te ontwikkel en te verseker dat monolitiese gedrag gehandhaaf word vir die hele voorafvervaardigde beton struktuur (Englekirk 2003). Die mees belangrike strukturele funksies van voorafvervaardigde beton verbindings sluit die volgende in; (i) verseker direkte oordrag van toegepaste kragte (vloei van kragte), (ii) ontwikkeling van strukturele kontinuïteit en integriteit, (iii) die verspreiding van puntbelastings, (iv) moet voorsiening maak vir die bewegings in die voorafvervaardigde element en konneksie self en laastens (v) verskaf doeltreffende rigiditeit en robuustheid vir die konneksie sone. Dus kan daar afgelei word dat daar baie faktore is wat bydra tot die algehele ontwerp en konstruksie fases van voorafvervaardigde beton verbindings. Die doel van hierdie studie is om aspekte te identifiseer en te ondersoek wat die ontwerp en konstruksie van aspekte beton verbindings wel beïnvloed. Die studie sal hoofsaaklik fokus op voorafvervaardigde beton en verbindings voorkeure van persone in die Suid-Afrikaanse konstruksiebedryf. Tydens die studie was persone in die industrie (kontrakteurs en konsultante) ook gevra om sekere aspekte en kwellings wat verband hou met voorafvervaardigde beton asook die verbindings te identifiseer. Die antwoorde wat verkry was uit die industrie deelnemers kan toepaslik gebruik om word riglyne en voorkeure op te stel wat vervolglik gebruik en toegepas kan word in die konstruksie bedryf van Suid Afrika. Die riglyne kan effektief gebruik word om voorafvervaardigde beton asook die verbindings te verbeter en persone in die konstruksie bedryf in te lig oor voorkeure en toepassings van hierdie metode.

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Kelly, Patrick James. "Bearing Zone Cracking of Precast Prestressed Concrete Bridge Girders." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14555.

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This thesis presents the results of a research project that tested five friction reducing techniques on the bearing ends of precast prestressed concrete bridge girders. The five techniques were the following: an oil coated surface, embedded steel plate with an oil coated surface, embedded steel angle with an oil coated surface, teflon pad, and a wax lubricant.

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Holland, Robert Brett. "Durability of precast prestressed concrete piles in marine environments." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44859.

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In this research, two phases of work were conducted. First, an investigation into the durability concerns for precast prestressed concrete piles exposed to marine environments was conducted. The investigation characterized the durability concerns of chemical, biological, and physical deterioration mechanisms. The results of this study were used to develop potential high performance marine concretes (HPMC) that would be capable of 100+ year service lives in marine environments. Extensive durability testing and service life modeling of the HPMC was performed. Chloride ingress resistance was investigated using accelerated and long-term test procedures and the results used to perform service life modeling to predict the time before corrosion initiation. Sulfate resistance characterization was performed using multiple techniques to characterize the physical and chemical behavior of binder compositions containing binary or ternary mixes containing cement and supplementary cementitious materials (SCM's) subjected to a sulfate-laden environment. Accelerated carbonation testing and material characterization led to the finding of relationships in the chemical composition of mix designs and the observed durability and the results used to perform corrosion initiation service life modeling. An investigation into the influence of self-healing of cracked concrete led to fundamental findings on the behavior of chloride ingress for cracked concrete structures in marine environments. The results of this research led to the development of concrete mix designs capable of providing service lives over 100 years in Georgia's marine environments, as well as the advancement of the current state of knowledge on the durability characteristics of ternary mix designs.

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Shariatmadar, Hashem. "Seismic response of connections in precast concrete double-tees." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30386.pdf.

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35

Lim, Tik Lun William. "Seismic evaluation and retrofit of a precast concrete structure." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81552.

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A single-storey precast concrete structure constructed in 1963 with masonry-infilled walls was selected for a seismic evaluation. The structure is located in the Montreal region, and is considered a post-disaster emergency building since it houses spare parts for municipal facilities. The warehouse was first evaluated through a visual inspection and identified as being seismically vulnerable. A series of three-dimensional models of the structure were analyzed to evaluate the seismic performance of the structure with respect to the seismic design requirements of the 1995 and 1965 edition of National Building Code of Canada (NBCC). The structural models were analyzed using a linear static analysis accounting for the effects of different diaphragm configurations on the lateral load resisting columns and the effects of masonry-infilled walls. The seismic analyses showed that the warehouse does not satisfy either of the NBCC 1995 and NBCC 1965 requirements. A seismic rehabilitation scheme is proposed comprising the addition of reinforced concrete shear walls, steel braces and an upgraded roof diaphragm. The proposed retrofit satisfies the seismic design requirements of NBCC 1995. Finally, the proposed seismic design provisions of NBCC 2005 are briefly summarized and the impact of the new seismic design provisions on the retrofitted structure is discussed.

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36

Tang, Kangkang. "Precast Concrete Paving Products made with Recycled Demolition Aggregate." Thesis, University of Liverpool, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507499.

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37

Jaafar, Mohd Saleh. "Time-dependent analysis of continuous precast prestressed concrete beams." Thesis, University of Sheffield, 1999. http://etheses.whiterose.ac.uk/3465/.

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A literature survey on the subject of construction, analysis and design of precast prestressed concrete beams made continuous has been conducted from which various methods of achieving continuity between the precast units have been identified. A need to re-evaluate the analysis and design of such structures has been established with special emphasis on the time-dependent aspects. An extensive evaluation of the time-dependent properties of concrete and the time- dependent behaviour of reinforced and prestressed concrete structures has been conducted. The evaluation used widely accepted methods of prediction for the material properties and four different analytical procedures for the behaviour of the structures. In a preliminary evaluation of the material properties, the methods of prediction based on the CEB78, CEB90 and ACI recommendations have been compared. This was followed by a more extensive parametric study of the factors affecting the material properties of plain concrete using the CEB90 recommendations. In a preliminary evaluation of the analytical procedures for structures subject to varying stress, the time- dependent behaviour of reinforced concrete sections using the Effective Modulus Method (EMM), Rate of Creep Method (RCM), Age-adjusted Effective Modulus Method (AEM) and Superposition Method (SSM) have been compared. This was followed by a more extensive evaluation of the factors affecting time-dependent behaviour of simply supported prestressed concrete beams using the AEM method. An evaluation of the parameters affecting the time-dependent behaviour of continuous precast prestressed concrete beams has been conducted using the SSM method which was based on a finite element analysis of prestressed concrete structures using the commercially available package, ADAPT. Both the AEM and ADAPT analyses have been compared against each other, and verified satisfactorily against a large number of experimental results. A special procedure to include cracked section properties has also been included into ADAPT analysis and it was found to improve time-dependent predictions of cracked reinforced concrete beams. Using the available features in ADAPT, the evaluation of continuous precast prestressed concrete has been extended to members connected using other methods of achieving continuity. Based on this study, several recommendations have been made on the treatment of the methods of prediction for the material properties and for the analysis of structures under varying state of stress, and on the analysis and design of continuous precast prestressed beams using unstressed reinforcement to provide continuity.

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Gordon, Stuart Ross. "Joints for precast decks in steel concrete composite bridges." Thesis, Heriot-Watt University, 2006. http://hdl.handle.net/10399/1109.

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Mahdi, Ali Abdulkarim. "Moment-rotation behaviour of connections in precast concrete structures." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387185.

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Kuttab, Atallah Shafic. "Behaviour of grouted dowelled connections between precast concrete columns." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38076.

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Vella, Jean Paul. "Development of novel connection methods between precast concrete panels." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/54755.

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This thesis addresses the design and behaviour of narrow cast in-situ joints between precast concrete elements in which continuity of reinforcement is achieved through overlapping headed bars. The use of headed bars minimises the required reinforcement lap length and hence joint width, thereby, maximising the area of precast concrete units. Confining reinforcement in the form of transverse bars and vertical shear studs is installed within the joint. Improved understanding of the behaviour of such joints is obtained by means of experimental testing and numerical analysis. In total, 32 tensile specimens and five flexural specimens were tested. The main longitudinal reinforcement in all specimens consisted of 25 mm diameter headed bars with 70 mm square heads. The tests investigated the influence on joint performance of concrete strength, confining shear studs, transverse bar arrangement, headed bar lap length and spacing, and out-of-plane offset of precast planks. For tensile specimens, a lap length of 100 mm with four 16 mm transverse bars and concrete compressive strength of 28 MPa was sufficient for headed bar yield. Ductile flexural failure, with headed bar yield, was achieved with the same lap length, two 20 mm transverse bars and concrete compressive strength of 39 MPa. A nonlinear finite element model (NLFEM) is presented with results showing that it captures the behaviour of the joint well. Additional parametric studies carried out with the validated NLFEM provide otherwise unavailable insights into joint behaviour. In conjunction with an appropriate safety format, the model is considered suitable for the design of standard joint configurations. Analytical models based on the strut-and-tie method and upper bound plasticity are presented. The models were found to give reasonable predictions of joint strength, but are not capable of fully capturing the observed joint behaviour. An improved strut and tie design method is suggested and recommendations are made for optimising joint design.

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Zang, Jin. "Investigation into a beam-column connection in precast concrete." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/2836.

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Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2010. ENGLISH ABSTRACT: Pre-cast sections have the advantages of structural efficiency, better quality control and less construction time, which enable them to be widely used in building structures. The connections of pre-cast buildings play a vital role for the stability and strength of structures. Nowadays, more attention is drawn to the aesthetical appearance of building structures, especially by architects. The Hidden Corbel Connection (HCC) was then developed to make the building structures stable and aesthetically pleasing. A modified HCC was designed and investigated in this study. Amongst all the mechanisms in the connection zone, the mechanism of the end anchorage length of tension reinforcement plays a key role in the economy of the connection and is hence further investigated. In order to investigate whether the end anchorage length of tension reinforcement can be reduced for a simply supported beam, a 2D non-linear finite element model is used to analyze the stress distribution inside the connection zone. Based on the stress distribution in the connection zone, the tensile force was calculated at the face of the support, which directly correlates to the required end anchorage length of tension reinforcement. The confinement in the connection zone increases the bond stress, which in turn reduces the required anchorage length of tension reinforcement. Therefore, a 3D model is used to analyze the region inside the modified HCC to find the position of the best confinement. By comparing the finite element (FE) results with Eurocode 2 (2004), and SABS 0100-1 (2000), it is demonstrated that the FE results require the shortest anchorage length, while the longest anchorage length is specified in SABS 0100-1 (2000). Based on the comparison between the FE results and the design codes, a laboratory experiment was then performed to determine if the end anchorage length of tension reinforcement can be reduced. Four beams with different support conditions and with different end anchorage length of tension reinforcement were tested. The results of the laboratory experiment indicate that the end anchorage length for simply supported beams can be shortened from the specification of SABS 0100-1 (2000).

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Görgün, Halil. "Semi-rigid behaviour of connections in precast concrete structures." Thesis, University of Nottingham, 1997. http://eprints.nottingham.ac.uk/11294/.

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Multi-storey precast concrete skeletal structures are assembled from individual prefabricated components which are erected on-site using various types of connections. In the current design of these structures, beam-to-column connections are assumed to be pin jointed. This current research work focuses on the flexural behaviour of the beam-to-column connections and their effect on the behaviour of the global precast concrete frame. The experimental work has involved the determination of moment-rotation relationships for semi-rigid precast concrete connections both in full scale connection tests and smaller isolated joint tests. This has been done using the so called "component method" in which the deformation of various parts of the connection and their interfaces are summated, and compared with results from full scale sub-frame connection tests. The effects of stress redistribution, shear interaction etc. are taken of by linear transformation in the results from the full scale tests, enabling parametric equations to be formulated empirically in order to describe the semi-rigid behaviour. Eight full scale column-beam-slab assemblages were tested to determine the (hogging) moment-rotation behaviour of double (balanced loading) and single sided in-plane connections. Two of the most common types of connection were used, the welded plate and the billet type. Proprietary hollow core slabs were tied to the beams by tensile reinforcing bars, which also provide the in-plane continuity across the joint. The strength of the connections in the double sided tests was at least 0.84 times the predicted moment of resistance of the composite beam and slab. The strength of the single sided connections was limited by the strength of the connection itself, and was approximately half of that for the double sided connection, even though the connection was identical. The secant stiffness of the connections ranged from 0.7 to 3.9 times the flexural stiffness of the attached beam. When the connections were tested without the floor slabs and tie steel, the reduced strength and stiffness were approximately a third and half respectively. This remarkable contribution of the floor strength and stiffness to the flexural capacity of the joint is currently neglected in the design process for precast concrete frames. Measurements of the extent of damaged zones near to the connection in full scale tests showed that, unlike steel connections, semi-rigid behaviour in precast concrete does not occur at a single nodal position. In general the double sided connections were found to be more suited to a semi-rigid design approach than the single sided ones. Analytical studies were carried out to determine empirical design equations for column effective length factors β in unbraced and partially braced precast concrete frames. The main variables were the relative flexural stiffness α of the frame members, and the relative linear rotational stiffness Ks of the connection to that of an encastre beam. The variation of β factors with Ks and α are presented graphically and in the form of design equations similar to those currently used in BS 8 110. The change in the response of a structure is greatest when 0< Ks <1.5 where β is found to be more sensitive to changes in Ks than α. When Ks >2 the changes in the behaviour are so small that they may be ignored within the usual levels of accuracy associated with stability analysis. This is an important finding because the experiments have found Ks to be generally less than 2 for typical sizes of beam. The results enable designers to determine β factors for situations currently not catered for in design codes of practice, in particular the upper storey of a partially braced frame. A design method is proposed to extend the concrete column design approach in BS 8110 and EC2, whereby the strength and semi-rigid stiffness of the connection enables column bending moments to be distributed to the connected beams. However, the suitability of each type of connection towards a semi-rigid design approach must be related to the stiffness and strength of the frame for which it is a part.

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Hashim, Nor Fazilah Mohd. "Vulnerability of precast concrete frames with semi-rigid connections." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683736.

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The progressive collapse of a structure occurs when local failure of a primary structural component leads to the collapse of adjoining members which in turn leads to further collapse through a chain reaction. Often the total damage is disproportionate to the original cause and is associated with a low probability event. The destruction of the World Trade Centre in 200 I due to aircraft impact is an example. Several studies on progressive collapse, mainly of steel structures, have resulted in changes to analysis and design guidelines. In precast concrete structures, connections play an important part in ensuring the safety of the whole structure. Current design practice is to assume these as pinned or rigid but this cannot be relied upon for safety against progressive collapse. The aim of this thesis is to examine the vulnerability of the behaviour of concrete frames with semi-rigid connections. The numerical responses of precast concrete frames with billet connections were studied. The connection was modelled by zero-length spring elements with rotational stiffness values at the ends of beams. These values were obtained from moment-rotation (M-θ ) relationships. A 3-dimensional finite element model was built and used to develop M-θ ) relationship of precast billet connection. Results demonstrate that rotational stiffness of billet connection (23138kNm/rad) leads to a fixity factor of 0.4 which is significantly different from the current practice of pinned connection. A 5-storey concrete building with different types of connection was analysed for the progression of damage after an accidental action. Linear static and nonlinear dynamic analyses associated with alternative load path method were performed. The collapse potential was assessed through demand capacity ratio, maximum deflection, ductility and rotation demand. Analyses show that precast frame with semi-rigid connections has higher potential than rigid connection, when one internal load-bearing element is damaged. Several parametric studies were conducted to investigate the sensitivity of progressive collapse. Results show that number of floors, location of column failure, connection flexibility and duration of column removal do affect the collapse potential results. Of these, the location of column failure is the most significant and the duration of column failure the least. In addition, the dynamic impact factor for the frame with semi-rigid connections were found to be 35% less than the usual guideline of 2. Finally, a new global damage index is proposed to estimate damage as a function of column location, fixity factor and local damage measure. A good relationship was found between the index, connection rigidity and damage.

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Wan, Ge. "Analytical Development of Capacity Design Factors for a Precast Concrete Diaphragm Seismic Design Methodology." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195082.

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The primary objective of the dissertation work is to examine the capacity of precast concrete diaphragms. This work is part of a multi-university research effort to develop a new seismic design methodology for precast/prestressed concrete floor diaphragms. To accomplish this, two-dimensional finite element (FE) models of precast floor diaphragms are created, including new elements to match the response of reinforcing details under combined forces. Using these models, nonlinear static "pushover" analyses are performed by applying body forces in the plane of the floor.The analyses are composed of three major parts:(1) Parametric studies to determine the required diaphragm shear strength relative to design (flexural) strength, termed "shear reinforcement overstrength", to promote a ductile mechanism in precast diaphragms. The performance of precast diaphragms with different shear reinforcement overstrength is examined. Appropriate shear reinforcement overstrength design factors are proposed to produce certain performance targets, in terms of a number of key parameters related to diaphragm geometry and the properties of the diaphragm reinforcing details.(2) Parametric studies to examine the effects of "secondary" diaphragm elements (spandrels, internal beams) on precast diaphragm behavior. Though not directly counted in design to participate diaphragm action, the secondary elements and their connections to the main diaphragm may modify the strength, stiffness and deformation capacity of the diaphragm. Analytical studies are performed to examine their effect on the global characteristics and local demands of precast floor diaphragms. The parameters evaluated include the characteristics of the connection details, the seismic hazard level used in design, diaphragm geometry, and layouts of spandrels and internal beams.(3) Development of a rational method for calculating the service stiffness and yield strength of precast concrete diaphragms. The method involves input of diaphragm geometry and reinforcing details. The method is verified analytically through comparisons to a set of FE analyses for an idealized diaphragm representation (regular single span diaphragm idealized with simple end supports). The method verified for a single set of diaphragm reinforcement details is used to estimate the properties over a range of untopped and topped diaphragm systems. Consideration of spandrel and internal beams in the method is discussed.

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Baran, Mehmet. "Precast Concrete Panel Reinforced Infill Walls For Seismic Strengthening Of Reinforced Concrete Framed Structures." Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12606137/index.pdf.

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The importance of seismic rehabilitation became evident with 1992 Erzincan Earthquake, after which a large number of reinforced concrete buildings damaged in recent earthquakes required strengthening as well as repair. In the studies related to rehabilitation, it has been realized that inadequate lateral stiffness is one of the major causes of damage in reinforced concrete buildings. Recently, economical, structurally effective and practically applicable seismic retrofitting techniques are being developed in METU Structural Mechanics Laboratory to overcome these kinds of problems. The strengthening technique proposed in this thesis is on the basis of the principle of strengthening the existing hollow brick infill walls by using high strength precast concrete panels such that they act as cast-in-place concrete infills improving the lateral stiffness. Also, the technique would not require evacuation of the building and would be applicable without causing too much disturbance to the occupant. For this purpose, after two preliminary tests to verify the proper functioning of the newly developed test set-up, a total of fourteen one-bay two story reinforced concrete frames with hollow brick infill wall, two being unstrengthened reference frames, were tested under reversed cyclic lateral loading simulating earthquake loading. The specimens were strengthened by using six different types of precast concrete panels. Strength, stiffness, energy dissipation and story drift characteristics of the specimens were examined by evaluating the test results. Test results indicated that the proposed seismic strengthening technique can be very effective in improving the seismic performance of the reinforced concrete framed building structures commonly used in Turkey. In the analytical part of the study, hollow brick infill walls strengthened by using high strength precast concrete panels were modelled once by means of equivalent diagonal struts and once as monolithic walls having an equivalent thickness. The experimental results were compared with the analytical results of the two approaches mentioned. On the basis of the analytical work, practical recommendations were made for the design of such strengthening intervention to be executed in actual practice.

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Barnes, Robert Wesley. "Development length of 0.6-inch prestressing strand in standard I-shaped pretensioned concrete beams /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.

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Lee, Jaeman. "Flexural and Shear Failure Mechanisms of Precast/Prestressed Concrete Members." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174917.

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Pilette, Claude F. "Seismic response and design of single-storey precast concrete buildings." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70190.

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A series of eight full-scale precast concrete columns and one precast pretensioned wall panel were tested to determine their reversed cyclic loading responses. The specimens represent typical single-storey precast members including the connections to the foundations. This experimental study illustrates the performance of specimens designed using the current design approach recommended by PCI and CPCI. Methods of increasing the stiffness of the connections and improving the levels of ductility are presented. Details consistent with the seismic design provisions of the CSA Standard were investigated and the resulting performance of the columns and the panel are assessed in terms of expected R factors of the National Building Code of Canada (1990). Analytical models are presented to enable the prediction of the reversed cyclic loading responses of the precast column-foundation and wall-foundation subassemblages. These analytical models are compared with the test results and also enabled the assessment of the performance of single-storey precast concrete structures by non-linear dynamic analyses. Design guidelines are presented for single-storey precast structures located in moderate seismic zones.

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Sudarno, Iwan. "Performance of thin precast concrete wall panels under dynamic loading." Thesis, University of Canterbury. Department of Civil Engineering, 2003. http://hdl.handle.net/10092/2285.

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Slender precast concrete wall panels are currently in vogue for the construction of tall single storey warehouse type buildings. Often their height to thickness ratio exceed the present New Zealand design code (NZS 3101) limitations of 30:1. Their real performance under earthquake attack is unknown. Therefore, this study seeks to assess the dynamic performance of slender precast concrete wall panels with different base connection details. Three base connections (two fixed base and one rocking) from two wall specimens with height to thickness ratios of 60:1 were tested under dynamic loading. The two fixed based walls had longitudinal steel volumes of 1.27% to 0.54% and were tested on the University of Canterbury shaking table to investigate their proneness to out-of-plane buckling. Based on an EUler-type theoretical formula derived as part of the study, an explanation is made as to why walls with high in-plane capacity are more prone to buckling. The theory was validated against the present and past experimental evidence. The rocking base connection designed and built in accordance with a damage avoidance philosophy was tested on the shaking table in a similar fashion to the fixed base specimens. Results show that in contrast with their fixed base counterparts, rocking walls can indeed fulfil a damage-free design objective while also remaining stable under strong earthquake ground shaking.

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Dissertations / Theses on the topic 'Precast concrete'

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