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1
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.
Повний текст джерелаАнотація:
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.
2
Srour, Mahdi. "Rocking system for seismic protection of reinforced concrete structures." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3255/.
Повний текст джерела
3
SCHWARTZ, CHRIS J. "STRUCTURAL INVESTIGATION OF A FIBER REINFORCED PRECAST CONCRETE BOX CULVERT." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1121016977.
Повний текст джерела
4
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.
Повний текст джерелаАнотація:
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.
5
Júnior, Luiz Álvaro de Oliveira. "Ligação viga-pilar em elementos pré-moldados de concreto solidarizados por concreto reforçado com fibras de aço: análises estática e dinâmica." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-13082012-083304/.
Повний текст джерелаАнотація:
No presente trabalho, utiliza-se concreto com fibras de aço, traspasse de armaduras e chaves de cisalhamento para desenvolver uma ligação viga-pilar capaz de resistir a ações cíclicas e dinâmicas e que possa ser empregada na pré-moldagem de estruturas de casas de força de usinas hidrelétricas. Para atingir este objetivo, inicialmente foram realizados ensaios de caracterização dos materiais, cujos resultados mostraram aumentos de 34% na resistência à tração na flexão, 16% na resistência à compressão e 33% na tenacidade, comprovando os efeitos benéficos das fibras de aço nas propriedades mecânicas do concreto. Em seguida, foram realizados ensaios de tração em tirantes, cujos resultados sugeriram que um comprimento de 15Ø é suficiente para que a emenda desenvolva as tensões de aderência de modo adequado; e ensaios de cisalhamento, cujos resultados mostraram que a ligação viga-pilar resiste a tensões de cisalhamento direto de até 0,77 MPa. Na sequencia, foram realizados ensaios cíclicos em dois modelos cruciformes para caracterização da ligação (um monolítico e outro de concreto pré-moldado, o qual empregava concreto com 1% de fibras na região da ligação), sendo o carregamento aplicado em cinco níveis de força, cada um com dez ciclos de carregamento e descarregamento. Os resultados desses ensaios mostraram que a ligação do modelo em concreto pré-moldado apresentou 85% da resistência do modelo monolítico e ruptura governada por flexão. Por fim, os ensaios dinâmicos foram realizados nos modelos cruciformes em três diferentes situações (íntegros, fraturados e após ruptura da ligação) para estimar o coeficiente de amortecimento, o qual sofreu uma redução de 31% após o ensaio cíclico. Simulações computacionais foram realizadas para complementar a investigação realizada neste trabalho. Elas mostraram representação aceitável da rigidez, mas não da resistência do modelo.In the present work, steel fiber reinforced concrete, splicing bars and shear keys are used in order to develop a beam-column connection able to support cyclic and dynamic loadings and which can be used in precasting power houses structures of power plants. To achieve this goal, tests were carried out to characterize the materials, which showed increases of 34% in flexural tensile strength, 16% in compressive strength and 33% in toughness factor, confirming the beneficial effects of steel fibers in mechanical properties of the concrete. Then, tensile tests were carried out on rods, whose results suggested that a length of 15Ø can assure appropriate development of bond stresses through the splice; and shear tests, whose results showed that the beam-column connection resists to shear stresses of up to 0,77 MPa on shear key. After, cyclic tests were performed in two cruciform models in order to characterize the beam-column connection (one monolithic and the other precast concrete, which employed 1% steel fiber reinforced concrete in connection region, being the loading applied in five loading levels, each one in 10 cycles of loading and unloading. Results of these tests showed that precast beam-column connection presented 85% of the strength presented by the monolithic model and bending failure. Finally, dynamic tests were performed in cruciform models in three different situations (uncracked, cracked and after failure) for estimating the damping ratio, which was reduced by 31% after cycles. Computer simulations were performed to complement the research developed in this work. They showed acceptable representation of stiffness, but the strength of the model.
6
Mintz, Brandon L. "Development of a Precast Concrete Supertile Roofing System for the Mitigation of Extreme Wind Events." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1665.
Повний текст джерелаАнотація:
Residential roofs have traditionally formed the weakest part of the structure. The connections of roofs to the walls has lacked a clear load path with the result that the structure is weak at this point, leading to the compromise of the structure. Indeed roofs have multiple points of failure that lead to the weakness of the residential structure as a whole. Even if structural failure does not occur, compromise the roofing membrane can lead to high repair costs and property loss. The failure lies in the complex forming of the roof components as the roof aesthetics are placed to protect the underlayment and the underlayment protects the sheathing and trusses. However, the aesthetics, such as the roof tile, not being structural can be damaged easily and lead to the compromise of the roofing system as well as endangering surrounding structures.
The shape of the roof tile lends itself well to structural design. The wave motion leads to structural redundancy and provides a significant ability to provide stiffness. Using the shape of the roof tile, a structure can be created to encapsulate the shape and provide structural strength. The aesthetics are already accounted for in the shape and the shape is strengthened according to necessity. A system has been devised for flexural strength and applicable connections to demonstrate the constructability and feasibility of creating and using such a system. Design concepts are accounted for, the components are tested and confirmed, and a full-scale test is carried out to demonstrate the concepts ability as a system.
The outgrowth of this work is to produce design tables that allow the designer the ability to design for certain building conditions. Taking the concepts of flexural strength and wall to roof, panel to panel, and ridge connections, the design is broken down into appropriate design parameters. Tables are developed that allow the concept to be used under different structural conditions and geographical needs. The conclusion allows us to show specifically how the concept can be applied in specific geographical regions.
7
Vitálišová, Barbora. "Návrh a posouzení vybraných částí ŽB nosné konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392081.
Повний текст джерелаАнотація:
The diploma thesis deals with the design of selected parts of reinforced concrete elements of the exhibition room. Simultaneously, the optimization of selected elements according to valid standards and Eurocodes was carried out and the impact of these changes on the economy of construction was developed.
8
Konečný, Michal. "Alternativní řešení montovaného železobetonového skeletu výrobní haly." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-391882.
Повний текст джерелаАнотація:
The aim of the thesis is to design a load-bearing precast concrete structure of production facility. Part of the diploma thesis is to design alternative roofing construction including economic comparison. Internal forces analysis was processed by Dlubal RFEM 5.16 software. In order to find out the expected results, were created simple bar models and the spatial model of the structure was processed later. Structural design report was created for selected elements of the concrete structure including drawings.
9
Bellucio, Ellen Kellen. "Comportamento de chumbadores embutidos em concreto com fibras de aço para ligações viga-pilar de concreto pré-moldado." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-24052016-111520/.
Повний текст джерелаАнотація:
O presente trabalho trata do estudo do comportamento de chumbadores grauteados inseridos em concreto com fibras de aço em ligações viga-pilar de estruturas de concreto pré-moldado. Este estudo é importante para se entender e poder quantificar a influência da rigidez deste componente no comportamento de ligações semirrígidas de estruturas de concreto pré-moldado. O objetivo do trabalho é estudar o mecanismo do chumbador no concreto com fibras de aço em ensaios específicos e avaliar também o comportamento de uma ligação viga-pilar de concreto pré-moldado utilizando estas fibras no consolo e no dente da viga. Nesta pesquisa foi realizado um programa experimental no Laboratório de Estruturas da EESC, uma análise numérica com o emprego do software DIANA® e uma comparação com formulações analíticas existentes para o cálculo da força última destes componentes. Foram ensaiados nove modelos experimentais para avaliar especificamente o mecanismo resistente do chumbador, variando-se os diâmetros das barras, sua inclinação e a porcentagem de fibras de aço no concreto. Além destes modelos, foi realizado ensaio de uma ligação viga-pilar de concreto pré-moldado para avaliar a rigidez da ligação com chumbador inserido em concreto com fibras de aço. Nos ensaios experimentais dos chumbadores observou-se que modelos com concreto com fibras de aço apresentam rigidez até 25% maior se comparado ao modelo com concreto convencional. Verificou-se que o graute utilizado para solidarizar os chumbadores exerce significativa influência na capacidade última do modelo, podendo diminuir em cerca de 30% a capacidade de carga. A ligação viga-pilar de concreto pré-moldado utilizando concreto com fibras de aço no consolo e no dente da viga se comportou de maneira satisfatória, não apresentando fissuração na interface dos diferentes concretos. Na comparação dos modelos ensaiados com as formulações teóricas extraídas de trabalhos de referência verificou-se que, para os modelos específicos de chumbador, a formulação existente é representativa. Para a ligação viga-pilar, alguns ajustes na formulação analítica se fizeram necessários para considerações de efeitos de grupo e de borda observados e decorrentes da utilização de dois chumbadores na ligação proposta neste trabalho.This research deals with the study of the behavior of grouted dowels embedded in concrete with steel fibers. This study is important to understand and quantify the stiffness transmitted by this component in a semi-rigid connection of precast concrete structures. The objective is to study the mechanism of the dowel in the concrete with steel fibers and evaluate the mechanical behavior of a precast beam-column connection using this type of concrete on the corbels and in the dapped-end beam. In this research, an experimental program in the EESC Structures Laboratory was carried out, as well as a numerical analysis with the use of DIANA® software and a comparison with existing formulations to calculate these components. Nine models were experimentally tested to specifically evaluate the dowel resistant mechanism by varying the diameters of the bars, the declination and the percentage of steel fibers in concrete. Furthermore, an experimental test was performed in order to evaluate the behavior of the connector. The results indicate that for the dowels with concrete and steel fibers, the ultimate capacity of the connection occurs by failure of the connector (excessive deformation of the bars), while in conventional concrete this capability is associated with the rupture of the concrete and that the concrete with steel fibers decreases by 25% the deformability of the models. The grout has a significant impact on the ultimate capacity of the model, which may increase in less than 30%. In the analysis of the beam-column connection, it is possible to observe that the proposed connection exceeds by more than 20% the ultimate capacity compared to traditional beam-column connections. In comparing the theoretical models tested with the formulations shown by previous studies, it was found that for specific models dowels, the existing formulation is representative. For the beam-column connection, adjustment was performed in the previous formulation considerations group and edge effects that occur due to the use of two dowels on the tested connection.
10
Al-Soudani, Maha. "Diagnosis of reinforced concrete structures in civil engineering by GPR technology : development of alternate methods for precise geometric recognition." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30090.
Повний текст джерелаАнотація:
La méconnaissance de la géométrie réelle d'une structure mène à une évaluation incorrecte de son état. Par conséquent, une estimation imprécise de sa capacité portante, sa durabilité, sa stabilité et la nécessité de mettre en place une réparation ou un renforcement. En outre, l'optimisation du temps requis pour le processus de réparation a besoin de bien connaître les différentes parties de la structure à évaluer et également pour éviter les zones critiques telles que les aciers, les câbles, etc., lors de la réparation. Par conséquent, il est nécessaire d'utiliser des techniques d'évaluation non destructive (END) afin de connaître la géométrie réelle de la structure, notamment l'emplacement des armatures dans les structures en béton armé. Le GPR est considéré comme une technique non-destructive idéale pour détecter et localiser les renforts. Cependant, sa précision de localisation est limitée. Le but de ce projet de recherche a donc été d'accroître la précision du GPR en matière de reconnaissance géométrique interne de structures en béton armé. L'objectif principal de cette étude est de localiser précisément le positionnement des armatures dans le plan ausculté ainsi qu'en profondeur. Pour atteindre cet objectif, une nouvelle méthodologie de mesures et du traitement des signaux GPR a été proposée dans cette étude. Plusieurs configurations d'acquisition de données en utilisant des signaux simulés sont testées pour proposer et développer un algorithme d'imagerie du milieu de propagation afin de définir sa géométrie interne et de localiser précisément les barres de renforcement. Des traitements supplémentaires sont appliqués pour améliorer la précision de la détection et pour identifier les différentes interfaces dans le milieu testé. L'algorithme et le traitement sont appliqués aux signaux simulés. Des validations expérimentales ont ensuite été appliquées aux signaux réels acquis sur différentes dalles en béton armé. L'objectif est de tester la capacité de l'algorithme d'imagerie proposé pour localiser différents objets enfouis. Les résultats encourageants montrent que cet algorithme est capable d'estimer la position de différents objets enfouis et pas uniquement les armatures avec une erreur d'estimation de (0-1) mm. Les performances de l'algorithme ont été comparées à celles d'une méthode de migration et aux résultats de mesure obtenus avec un pachomètre. Ces comparaisons ont systématiquement révélé une meilleure précision de la localisation avec l'algorithme développé.Une autre étude a été proposée dans ce travail en testant l'algorithme avec des signaux réels modifiés. Ces signaux sont produits en réduisant le gain le moins possible. La conclusion la plus évidente de cette étude est que l'algorithme proposé est capable de localiser les différents objets même si les signaux réfléchis par eux sont de faible amplitudeLack of acquaintance in the real geometry of a structure leads to incorrect evaluation of its state. Consequently, this will lead to inaccurate estimation of bearing capacity, durability, stability and moreover, the need for repair or strengthening. Furthermore, optimization of the required time for repair process needs to well recognize the parts of structure to be assessed and also to avoid the critical zones such as reinforcing bars, cables, etc., during repairing. Therefore; it becomes necessary to use a non-destructive testing (NDT) method in order to know the real geometry of structure in particular, the location of reinforcements in reinforced concrete structures. GPR is considered as an ideal non-invasive technique in detecting and locating these reinforcements. However, its accuracy in localization is limited. The aim of this research project has therefore been to increase the accuracy of GPR in recognizing the internal geometry of reinforced concrete structures. The main objective of this study is to locate accurately the position of reinforcements into three dimensions. To achieve this purpose, a new methodology for GPR measurement and processing is proposed in this study.Several configurations of data acquisition using simulated signals are tested to propose and develop an appropriate imaging algorithm for the propagation medium to imagine its internal geometry and to locate accurately the reinforcing bars. Further processing are applied to improve the accuracy of detection and to identify the different interfaces in the tested medium. Both algorithm and processing are applied on simulated signals. Subsequent experimental validations have been applied using real signals acquired from different real reinforced concrete slabs. The goal is to test the ability of proposed imaging algorithm for the localization of different targets. The encouraging results indicate that this algorithm is able to estimate the position of different buried targets and not only the reinforcing bars with an estimation error of (0-1)mm.The performance of proposed algorithm has compared to those of migration method and to the results obtained from pachometer. These comparisons have systematically revealed a better localization accuracy using the developed algorithm.Another study has been proposed in this work by testing the algorithm using modified real signals. These signals are produced by reducing the gain as less as possible. The most obvious finding to emerge from this study is that the proposed algorithm is able to localize the different goals even if the signals reflected by them are of low amplitude
11
Tasini, Lorenza. "Study of a beam-column joint of a precast system by nonlinear numerical analysis." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11763/.
Повний текст джерелаАнотація:
The present work consists of a detailed numerical analysis of a 4-way joint made of a precast column and two partially precast beams. The structure has been previously built and experimentally analyzed through a series of cyclic loads at the Laboratory of Tests on Structures (Laboratorio di Prove su Strutture, La. P. S.) of the University of Bologna. The aim of this work is to design a 3D model of the joint and then apply the techniques of nonlinear finite element analysis (FEA) to computationally reproduce the behavior of the structure under cyclic loads. Once the model has been calibrated to correctly emulate the joint, it is possible to obtain new insights useful to understand and explain the physical phenomena observed in the laboratory and to describe the properties of the structure, such as the cracking patterns, the force-displacement and the moment-curvature relations, as well as the deformations and displacements of the various elements composing the joint.
12
Kurt, Efe Gokce. "Investigation Of Strenghthening Techniques Using Pseudo-dynamic Testing." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612181/index.pdf.
Повний текст джерелаАнотація:
Pseudo-dynamic testing was employed to observe the seismic performance of three different retrofit methods on two story three bay reinforced concrete frame structures. The three test frames have hollow clay tile (HCT) infills in the central bay. All of the test frames represent the seismic deficiencies of the Turkish construction practice such as use of plain reinforcing bars, low strength concrete and insufficient confining steel. Two non-invasive and occupant friendly retrofit schemes suggested in the Turkish Earthquake Code, namely use of Fiber Reinforced Polymers and precast concrete panels integrated on the HCT infills and traditional approach of adding concrete infill wall were employed. Specimens were subjected to three different scale levels of North-South component of Duzce ground motion. Reference specimen experienced severe damage at 100% scale level and reached collapse stage due to the loss of integrity of the infill wall and significant damage on the boundary columns. The retrofitted test structures were able to survive the highest level 140% Duzce ground motion. Test results confirmed the success of the retrofit methods for simulated earthquake loads.
13
Čihák, Tomáš. "Tělocvična - prefabrikovaný skelet." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227738.
Повний текст джерелаАнотація:
This master thesis deals with a draft of precast concrete frame structure on the case of gymnasium building. The major part of this work are transversal and longitudinal frames, consisted of footings, columns, girders and precast floor slab. Other parts of the building are not solved. Thesis consists both static calculations and drawings.
14
Hrvolová, Markéta. "Posouzení železobetonové konstrukce bytového domu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240277.
Повний текст джерелаАнотація:
The aim of the diploma thesis is static solution of selected parts of the residental house with formwork drawings and reinforcement drawings of designed structures included. Project describes the design and assessment of the monolitic slab structure, precast stair flights, basement loadbearing wall and retaining wall. For calculation of the internal forces was used software Scia Engineer.
15
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.
Повний текст джерела
16
Robinson, Gary P. "Design and performance of precast concrete structures." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14722.
Повний текст джерелаАнотація:
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.
17
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.
Повний текст джерелаАнотація:
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.
18
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.
Повний текст джерелаАнотація:
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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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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Görgün, Halil. "Semi-rigid behaviour of connections in precast concrete structures." Thesis, University of Nottingham, 1997. http://eprints.nottingham.ac.uk/11294/.
Повний текст джерелаАнотація:
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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Abdul, Aziz Farah Nora Aznieta. "Flexural strengthening of reinforced concrete beams using precast sifcon thin plate." Thesis, University of Nottingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446382.
Повний текст джерела
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Ervine, Adam. "Damaged reinforced concrete structures in fire." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6229.
Повний текст джерелаАнотація:
It is crucial for a building to maintain structural stability when subjected to multiple and sequential extreme loads. Safety and economic considerations dictate that structures are built to resist extreme events, such as a earthquakes, impacts, blasts or fires, without collapse and to provide adequate time for evacuation of the occupants. However, during such events, some structural damage may be permissible. Design codes do not account for the scenario where two extreme events occur consecutively on a structure nor do they address the situation of the structure having some initial damage prior to being subjected to a fire load. This work begins by detailing the major inconsistancies between designing reinforced concrete structures for extreme mechanical loads and designing for fire. The material behaviour and traits of the constitutive parts (i.e. the concrete and the steel), including post yielding behaviour, thermal relationships and their interaction with each other are all explored in detail. Comprehensive experimental and numerical investigations are undertaken to determine whether, and to what extent, phenomena such as tensile cracking and loss of the concrete cover affect the local and global fire resistance of a member or structure. The thermal propagation through tensile cracks in reinforced concrete beams is examined experimentally. A comparison is made between the rate of thermal propagation through beams that are undamaged and beams that have significant tensile cracking. The results show that, although small differences occur, there is no significant change in the rate of thermal propagation through the specimens. Consequently, it is concluded that the effects of tensile cracking on the thermal propagation through concrete can be ignored in structural analyses. Significantly this means that analyses of heated concrete structures which are cracked can be carried out with heat-transfer and mechanical analyses being conducted sequentially, as is currently normal and fully-coupled thermo-mechanical analyses are not required. The loss of concrete cover and the impact on the thermal performance is examined numerically. A comparison is made of the thermal propagation, beam deflections and column rotations between structures that are undamaged and structures that have partial cover loss in a variety of locations and magnitudes. Results show that any loss of cover can lead to unsymmetrical heating, causing larger deflections in both vertical and horizontal directions, which can result in a more critical scenario. It is concluded that the effect of cover loss on the thermal performance of the structure is extremely significant. A new approach to numerically simulating the loss of cover by mechanical means from a member is developed. This new approach provides the user with an extremely flexible yet robust method for simulating this loss of cover. The application of this method is then carried out to show its effectiveness. A large experimental study carried out at the Indian Institute of Technology, Roorkee and separately numerically modelled at the University of Edinburgh. Unfortunately, due to unforseen circumstances, the experimental data available is limited at this time and as a result the validation of the numerical simulation is limited. Through these investigations it is clear that it is necessary to develop a method in enhance the stability and integrity of the concrete when subjected to the scenario of a fire following another mechanically extreme event. Therefore, finally a method is proposed and experimentally investigated into the use of fibres to increase the post crushing cohesiveness of the concrete when subjected to thermal loads. Results show that the fibrous members display an increased thermal resistance by retaining their concrete cover through an enhanced post crushing cohesion. From this investigation, it is concluded that the use of fibrous concrete is extremely beneficial for the application of enhancing the performance under extreme sequential mechanical and thermal loading.
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黃玉平 and Yuping Huang. "Nonlinear analysis of reinforced concrete structures." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31233090.
Повний текст джерела
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Sangi, Abdul Jabbar. "Reinforced concrete structures under impact loads." Thesis, Heriot-Watt University, 2011. http://hdl.handle.net/10399/2485.
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Cavaco, Eduardo Soares Ribeiro Gomes. "Robustness of corroded reinforced concrete structures." Doctoral thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/11109.
Повний текст джерелаАнотація:
Dissertação para obtenção do Grau de Doutor em Engenharia CivilThe concept of structural robustness has seen growing interest in the last decades due to the occurrence of catastrophic consequences resulting from extreme events. The lack of structural robustness has been several times claimed as the major cause for the unmanageable consequences. However, the concept has never been accurately defined, and several different perspectives for robustness can be found in the literature. Structural robustness has been widely discussed for structures subjected to extreme events, however, the concept can also be useful in the context of more probable exposures, such as those resulting in structural aging. In fact, in the last 20 years, most developed societies have been facing the problem of infrastructure aging, and the maintenance demands already represent a significant fraction of governments investments in infrastructures. In this thesis a deep analysis on the essence of structural robustness is presented. The most relevant definitions and measures for robustness, suggested in the literature, are widely discussed in order to understand the difficulty in achieving a unique and consensual approach. In the context of structural aging, a new definition for robustness, including a complete methodology to assess it, is proposed in this thesis. Robustness is related with the structure ability to maintain adequate performance levels as damage increases. The competence of the proposed framework to assess robustness is proven in the context of structural aging, in particular in cases of reinforced concrete structures subjected to reinforcement corrosion. Structural performance of reinforced concrete structures is analyzed as corrosion on reinforcement increases. In this manner, a methodology to assess the most concerning effects, resulting from corrosion is presented. Different performance indicators, both deterministic and probabilistic, and structural types are analyzed. Robustness results obtained are discussed regarding the structural types more tolerant to corrosion of reinforcement. Finally the case of an existing bridge, presenting signs of severe corrosion, is analyzed and discussed in the context of the proposed robustness framework.
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Khalid, Huma. "Objective modelling of reinforced concrete structures." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9327.
Повний текст джерелаАнотація:
The finite element (FE) method is a powerful technique that can provide numerical solutions to the response of reinforced concrete (RC) structures. However, results obtained from FE models are often not objective in the sense that the numerical solutions of FE models depend on aspects such as the selection of mesh size, load step size etc. FE model objectivity aims at the development of FE models for which the predicted results converge with refinement. To date, many research studies have been carried out on the objectivity of FE solutions for RC structures. However, considerable uncertainty still exists because of the many parameters which are involved in the analysis. The parameters affecting FE analysis of RC structures may be divided into two groups: material parameters and procedural parameters. The main parameters related to the material behaviour are tension softening and interaction between steel reinforcement and concrete. On the other hand, the procedural parameters which affect directly the results of the analysis are the load step, mesh size, iterative scheme, and number of cracks allowed per load step, numerical integration rule, and the use of static vs. dynamic analysis. In an effort to investigate these parameters, the current research is primarily aimed towards developing finite element formulations and solution procedures that facilitate the objective modelling of RC structures. The present study focuses on a subset of the above parameters that appear to be most relevant to objective modelling. Two new formulations have been developed in this work which allows the objective modelling of RC beam-column members, including geometric and material nonlinearity as well as bond slip. Particular emphasis is placed on predicting crack localisation in the concrete and stress concentrations in the steel reinforcement across such cracks, as this is particularly relevant to the modelling of RC structures under extreme loading. Several verification and validation studies are presented in the thesis to illustrate the key features of the proposed formulations and their applicability to the objective modelling of RC framed structures.
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Huang, Yuping. "Nonlinear analysis of reinforced concrete structures /." [Hong Kong] : University of Hong Kong, 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13458917.
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Paschalis, Spyridon A. "Strengthening of existing reinforced concrete structures using ultra high performance fiber reinforced concrete." Thesis, University of Brighton, 2017. https://research.brighton.ac.uk/en/studentTheses/c07ce9c7-5880-4108-a0f2-68bf6ea50dd5.
Повний текст джерелаАнотація:
Most of the new Reinforced Concrete (RC) structures which are built nowadays have a high safety level. Nevertheless, we cannot claim the same for structures built in the past. Many of these were designed without any regulations, or are based on those which have proved to be inadequate. Additionally, it seems that many old structures have reached the end of their service life and, in many cases, were designed to carry loads significantly lower than the current needs specify. Therefore, the structural evaluation and intervention are considered necessary, so they can meet the same requirements as the structures which are built today. Existing techniques for the strengthening and retrofitting of RC structures present crucial disadvantages which are mainly related to the ease of application, the high cost, the time it takes to be applied, the relocation of the tenants during the application of the technique and the poor performance. Research is now focused on new techniques which combine strength, cost effectiveness and ease of application. The superior mechanical properties of Ultra High Performance Fiber Reinforced Concrete (UHPFRC) compared to conventional concrete, together with the ease of preparation and application of the material, make the application of UHPFRC in the field of strengthening of RC structures attractive. The present research aims to investigate the effectiveness of UHPFRC as a strengthening material, and to examine if the material is able to increase the load carrying capacity of existing RC elements. This has been achieved through an extensive experimental and numerical investigation. The first part of the present research is focused on the experimental investigation of the properties of the material which are missing from the literature and the development of a mixture design which can be used for strengthening applications. The second part is focused on the realistic application of the material for the strengthening of existing RC elements using different strengthening configurations. Finally, in the last part, certain significant parameters of the examined technique, which are mainly related to the design of the technique, are investigated numerically. From the experimental and numerical investigation of the present research it was clear that UHPFRC is a material with enhanced properties and the strengthening with UHPFRC is a well promising technique. Therefore, in all the examined cases, the performance of the strengthened elements was improved. Finally, an important finding of the present research was that the bonding between UHPFRC and concrete is effective with low values of slip at the interface.
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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.
Повний текст джерелаАнотація:
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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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.
Повний текст джерелаАнотація:
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.
31
Lindwall, Caroline, and Jonas Wester. "Modelling Lateral Stability of Prefabricated Concrete Structures." Thesis, KTH, Betongbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-188586.
Повний текст джерелаАнотація:
Stability calculations of prefabricated concrete structures with help of FEM-tools demand knowledge about how the elements are related to each other. This thesis concerns how joints between building elements affect the results when modelling prefabricated concrete structures, with demarcation to joints between hollow core (HC) slabs and between solid wall elements. The thesis also covers how the properties of the floor can be adjusted to account for the effects of the joints without modelling every single element. The work started by measuring the deflection of 10 HC-slabs jointed together and loaded in-plane acting as a deep beam, in a FE-model made with Robot™, from Autodesk®. The joints between the HC-elements were modelled either rigid or elastic, and the cross-section and the length of the HC-elements were varied. The linear elastic stiffness between the HC-elements was obtained from the literature as 0.05 (GN/m)/m. The results showed that a changed cross-section geometry gave greater differences in deformation than a changed length. The in-plane shear modulus was then adjusted for the HC-elements in the rigid cases until the same deflection was achieved as for the elastic cases. The result showed that the shear modulus in average for the different cross-section geometries and lengths had to be reduced with a factor of 0.1 to account for the joints. Based on the geometry of a castellated joint between prefabricated solid concrete walls, a calculation model was developed for its linear elastic stiffness. The result was a stiffness of 1.86 (GN/m)/m. To verify the calculated stiffness, a FE-model was developed consisting of a 30m high wall, loaded horizontally in-plane and with one or two vertical joints where the stiffness was applied. The deflection and the reaction forces were noted and the result from the calculated stiffness was compared to other stiffnesses and assessed reasonable. The reaction forces were shown to depend on the stiffness of the joint. The reduced in-plane shear modulus of the HC-elements and the calculated stiffness of the wall joints were then used in a FE-model of a 10-storey building stabilised by two units. The vertical reaction forces were analysed and the results showed 0.02 % difference in the reaction forces in the stabilising units when consideration of the joints between the HC-elements were taken into account and 0.09 % when the vertical joints in the shear wall were taken into account. The results for the wall joint differed from the results when only the wall was modelled. This was thought to be a result of that the floors counteract the shear deformations in the wall joints. The influence of the floor joints was not significant for the building considered in this thesis, but for buildings with non-continuous configuration of the stiffness in the shear walls the outcome may be another, in these cases the reduction factor may be useful.Vid stabilitetsberäkningar av prefabricerade betongstommar med hjälp av FEM-verktyg ställs krav på kunskap om hur elementen förhåller sig till varandra. Detta arbete berör hur fogar mellan byggnadselement påverkar modellering av prefabricerade betongstommar med avgränsning till fogar mellan håldäckselement och mellan solida väggelement. Arbetet berör även en studie i hur ett bjälklags egenskaper kan justeras så att fogarnas effekt kan tillvaratas utan att modellera varje enskilt håldäckselement. Arbetet inleddes med att utböjningen analyserades hos 10 st ihopskarvade håldäckselement, lastade i dess plan likt en hög balk, i en FE-modell skapad i programmet Robot™, från Autodesk®. Fogarna mellan håldäcken modellerades som antingen rigida eller elastiska och håldäckens tvärsnittsgeometri och längd varierades under testet. Den linjära styvheten mellan håldäcken togs från litteraturen som 0.05 (GN/m)/m. Resultatet visade att ändrad tvärsnittsgeometri gav större skillnader för deformationen än varierad längd på håldäcken. Håldäckens skjuvmodul justerades sedan i dess plan för de rigida testen tills dess att de uppnådde samma utböjning som de elastiska. Resultatet visade att skjuvmodulen behövdes reduceras med en faktor 0.1, i medeltal för de olika tvärsnittsgeometrierna och håldäckslängderna. Utefter geometrin på en fog med förtagningar mellan prefabricerade väggar togs en beräkningsmodell fram för den linjärelastiska styvheten i väggfogarna. Resultatet blev en styvhet på 1.86 (GN/m)/m. För att verifiera den beräknade styvheten togs en FE-modell fram bestående av en 30m hög vägg lastad horisontellt i dess plan med en eller två vertikala fogar där en linjär styvhet applicerades. Utböjningen samt reaktionskrafterna noterades, resultatet för den uträknade linjära styvheten jämfördes med andra styvheter och bedömdes utifrån detta vara rimlig. Reaktionskrafterna visade sig vara beroende av styvheten på fogen. Den sänkta skjuvmodulen för håldäcken och den beräknade linjära elasticiteten för väggarna användes sedan i en FE-modell av en 10-våningsbyggnad med två stabiliserande enheter där de vertikala reaktionskrafterna analyserades. Resultatet visade att endast 0.02 procentenheter skiljer reaktionskrafterna i de stabiliserande enheterna då hänsyn tas till fogarna mellan håldäcken och 0.09 procentenheter då hänsyn tas till fogarna mellan väggarna. Resultatet skiljer sig från när endast väggen modellerades, vilket tros bero på att bjälklaget hjälper till att motverka deformationer i väggfogarna. Fogen mellan bjälklagselementen tros kunna ha större inverkan på en byggnad med stabiliserande enheter som drastiskt ändrar styvhet från ett plan till ett annat, i dessa fall kan den framtagna reduktionsfaktorn vara av nytta.
32
Kozumplík, Lukáš. "Železobetonová monolitická konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240145.
Повний текст джерелаАнотація:
The diploma thesis is focused on a structural analysis of a multi-storey office building. The Loadbearing structure is made of cast-in-place reinforced concrete. In the thesis there is analysed a selected floor slab, a column, a foundation pad, a part of loadbearing wall and a precast staircase. Computation of internal forces is carried out by computational software SCIA Engineer. The Results from the software are verificated via simplified manual method. Assessment of a structure is done according to valid standards and regulations.
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Salama, Assaad Ibrahim. "Repair of earthquake-damaged reinforced concrete structures." Thesis, Imperial College London, 1993. http://hdl.handle.net/10044/1/7259.
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34
Ciftci, Guclu Koray. "Nonlinear Analysis Of Reinforced Concrete Frame Structures." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615549/index.pdf.
Повний текст джерелаАнотація:
Reinforced concrete frames display nonlinear behavior both due to its composite nature and
the material properties of concrete itself. The yielding of the reinforcement, the non-uniform
distribution of aggregates and the development of cracks under loading are the main
reasons of nonlinearity. The stiffness of a frame element depends on the combination of the
modulus of elasticity and the geometric properties of its section - area and the moment of
inertia. In practice, the elastic modulus is assumed to be constant throughout the element
and the sectional properties are assumed to remain constant under loading.
In this study, it is assumed that the material elasticity depends on the reinforcement ratio and
its distribution over the section. Also, the cracks developing in the frame element reduces the
sectional properties. In case of linear analysis, the material and sectional parameters are
assumed to be constant. In practice, the modulus of elasticity E is a predefined value based
on previous experiments and the moment of inertia I is assumed to be constant throughout
the analysis. However, in this study, E and I are assumed to be combined. In other words,
they cannot be separated from each other throughout the analysis. These two parameters
are handled as a single parameter as EI . This parameter is controlled by the reinforcement
ratio and its configuration, sectional properties and deformation of the member.
Two types of analysis, namely a sectional and a finite element analyses, are used in this
study. From the sectional analysis, the parameter EI is calculated based on the sectional
geometry, material properties and the axial load applied on the section. The parameter EI is
then used in the finite element analysis to calculate the sectional forces and the nodal
displacements. For the nonlinear analysis, the Newton-Raphson iterative approach is
followed until convergence is obtained.
35
Hassanein, Alea El Din Mohamed. "Intermittent cathodic protection of reinforced concrete structures." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287182.
Повний текст джерела
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Na, Won-Bae. "Nondestructive evaluation of bar-concrete interface in reinforced concrete structures." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279890.
Повний текст джерелаАнотація:
The feasibility of detecting and quantifying delamination at the interface between steel (or GFRP) bar and concrete using ultrasonic guided waves is investigated in this study. These waves can propagate a long distance along the reinforcing steel (or GFRP) bar or concrete beam as guided waves and are sensitive to the interface bonding condition between the steel (or GFRP) bar and concrete. The traditional ultrasonic methods are good for detecting large voids in concrete but not very efficient for detecting delamination at the interface between concrete and steel (GFRP) bar since they use reflection, transmission and scattering of longitudinal waves by internal defects. In this study, special solid couplers between the steel/GFRP bar (or concrete beam) and ultrasonic transducers have been used to launch cylindrical guided waves (or Lamb waves) in the steel/GFRP bar (or concrete). This investigation shows that the guided wave inspection technique is an efficient and effective tool for health monitoring of concrete structures.
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Avilla, Junior Jovair. "Contribuição ao projeto e execução de lajes lisas nervuradas pré-fabricadas com vigotas treliçadas." Universidade Federal de São Carlos, 2010. https://repositorio.ufscar.br/handle/ufscar/4656.
Повний текст джерелаАнотація:
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Previous issue date: 2010-02-18The big surge in use of systems for flat slabs gave up the search for freedom in the definition and organization of architectural interior spaces in buildings. The design and construction of buildings on flat slabs, which allow great mobility in defining the internal space of the building and reducing its height. The slabs with prefabricated trussed beams using forms lost in blocks of expanded polystyrene (EPS) or removable forms, brought new perspectives to the design of flat slabs, allowing greater spans with low deadweight. The precast elements are lightweight, easy handling, transport and assembly, and require the use of molds and special equipment and requires little bracing. Computer programs have emerged in recent years provide more refined calculations that predict the behavior of the structure in service with greater precision. This way the designers have increased security in systems design less common as flat slabs ribbed, without internal beams, capitals and even edge beams. In Brazil the predominant culture in the design and implementation of flat slabs is given by the system option molded on site. The objectives of this study are: to seek answers to the prevailing cultural behavior, and to compare their advantages and disadvantages when compared with cast on site, presenting the normative regulations and simplified calculation method according to ABNT NBR 6118:2003, provide subsidies for the project and implementation of flat slabs with ribbed prefabricated trussed beams, provide a calculation method for the infinitely rigid diaphragm; present a real case study as a comparison of costs.
O grande impulso na utilização dos sistemas de lajes lisas deu-se pela busca de liberdade na definição e organização arquitetônica de espaços internos em edifícios. O projeto e execução de edificações em lajes lisas, permitem grande mobilidade na definição do espaço interno do edifício e na redução da sua altura final. As lajes pré-fabricadas com vigotas treliçadas que utilizam fôrmas perdidas em blocos de Poliestireno Expandido (EPS) ou fôrmas removíveis trouxeram novas perspectivas ao projeto de lajes lisas, permitindo vãos maiores com baixo peso próprio. Os elementos pré-moldados são leves, de fácil manuseio, transporte e montagem, dispensam o uso de fôrmas e equipamentos especiais e requerem pouco escoramento. Programas computacionais surgidos nos últimos anos propiciam cálculos mais refinados que permitem prever o comportamento em serviço da estrutura com maior precisão. Dessa maneira, os projetistas têm maior segurança no projeto de sistemas menos usuais, como lajes lisas nervuradas, sem vigas internas, capitéis e até mesmo vigas de borda. No Brasil, a cultura predominante no projeto e execução de lajes lisas se dá pela opção do sistema moldado no local. Nestes termos, os objetivos do presente trabalho são: buscar respostas para o comportamento cultural predominante; comparar suas vantagens e desvantagens em relação aos sistemas moldados no local; apresentar as regulamentações normativas e o método de cálculo simplificado segundo a ABNT NBR 6118:2003; fornecer subsídios para o projeto e execução das lajes lisas nervuradas pré-fabricadas com vigotas treliçadas; apresentar um método de cálculo para o diafragma infinitamente rígido e apresentar um estudo de caso real como comparativo de custos.
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Cornali, Fabrizio. "Evaluation of the Expected Annual Loss for Precast Concrete Industrial Structures." Doctoral thesis, Università degli studi di Bergamo, 2017. http://hdl.handle.net/10446/77277.
Повний текст джерелаАнотація:
Nel corso degli ultimi anni sono state condotte analisi e ricerche scientifiche riguardanti l’effetto che i fenomeni sismici hanno in termini di danni economici sulle opere colpite. Da questi studi è emersa l’importanza rivestita dall’aliquota di costo relativa al ripristino de i danni associati agli elementi non-strutturali (o secondari) e/o al contenuto dell’edificio. Questo vale specialmente nel settore industriale in cui, nella quasi totalità dei casi, il valore monetario degli impianti e delle installazioni interne è di gran lunga maggiore rispetto al valore della nuda struttura. Si pensi ad esempio ai danni subiti dalle numerose aziende diffuse nel territorio Emiliano a seguito dei recenti eventi sismici avvenuti nel Maggio del 2012.
In questo scenario si inserisce lo scopo principale della presente ricerca, ossia quello di sviluppare una metodologia semplice e affidabile in grado di consentire una stima precisa delle perdite economiche legate ai danni subiti dai terremoti, con particolare riferimento agli edifici prefabbricati industriali.
All’interno di questo progetto sono analizzati differenti modelli basati su un approccio probabilistico interdisciplinare che accorpa in sé: l’analisi della pericolosità del sito su cui sorge l’edificio, l’analisi della risposta strutturale, l’analisi del danno subito e la valutazione del costo associato per ogni componente vulnerabile. Partendo dai modelli di calcolo più raffinati, quali il PEER PBEE, si è giunti infine alla messa a punto di due procedure più semplificate e rapide, l’una basata su un approccio agli spostamenti per l’analisi strutturale e l’altra sull’impiego di una formulazione in forma chiusa in alternativa alla procedura raffinata.
L’impiego di tali procedure, richiede dapprima l’identificazione delle più comuni vulnerabilità caratterizzanti e riscontrabili negli edifici prefabbricati industriali e successivamente la conoscenza delle curve di fragilità e di costo per tutti gli elementi che possono dare origine ad eventuali perdite economiche.
Ad oggi però, la risposta sismica degli elementi non strutturali in edifici prefabbricati e l’interazione degli stessi con la risposta globale della struttura non è completamente definita ed in alcuni casi non è mai stata indagata, per tale motivo è attualmente oggetto di numerosi studi di ricerca. Molto spesso quindi le curve di fragilità e di costo non sono disponibili. Da qui nasce l’interesse d’indagare la risposta sismica nel fuori piano dei pannelli prefabbricati di tamponamento esterno, nonché l’entità delle forze nelle connessioni metalliche pannello-struttura. Oltre a questo è indagata pure l’influenza del carroponte e l’interazione dello stesso con la risposta sismica globale della struttura in edifici prefabbricati industriali in calcestruzzo armato.During the last few years, several analyses and scientific studies were conducted on existing buildings in terms of economic damages and losses on the affected buildings. These studies showed the importance of the rate of recovery costs associated to the damages of the non-structural elements (or secondary elements) and/or the contents of the building. Especially in the industrial field, in almost all cases the monetary value of the facilities and the internal installations is far greater than the value of the bare structure. Just think about the damages suffered by many companies spread in the Emilian territory following the recent earthquakes that occurred in May, 2012. The main purpose of the current research is framed in this scenario. To achieve this goal, a simple and reliable method capable of allowing an accurate estimation of the economic losses linked to the damage caused by earthquakes on precast reinforced concrete industrial buildings is developed. Within this project, different models of computation are critically studied and analysed. All of these methods are based fundamentally on a probabilistic and interdisciplinary approach, which incorporates: the hazard analysis of the site, the structural analysis, the damage analysis and the loss analysis suffered by each vulnerable component. Starting from the most refined PEER PBEE methodology, this research has led to the development of two more simplified and speedy procedures, one based on a displacement method for performing the structural analysis and the second method uses a closed formula as an alternative to the refined PEER PBEE methodology. The use of such procedures requires the identification of the most common vulnerabilities detectable in precast reinforced concrete buildings, as well as the knowledge of the fragility and the cost curves for all the vulnerable elements which can give rise to possible damages and then the monetary losses. Actually, the seismic response of the non-structural elements in precast reinforced concrete buildings and the interaction of the same with the global response of the structure is not completely defined and in some cases, it has never been investigated. Therefore, very often the fragility and the cost curves of the elements are not available: this is one of the reason why it is the subject of the most recent research studies. From this, the interest to inquire about the seismic response of the out-of-plane performance of the horizontal cladding panels was born. In addition, the influence of the overhead crane in the seismic response of precast buildings is also analysed.
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Feghali, Habib Labib. "Seismic performance of flexible concrete structures /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Haro, de la Peña Omar Arturo. "Modelling and analysis of retrofitted reinforced concrete structures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58767.pdf.
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Das, Satrajit. "Seismic Design of Vertically Irregular Reinforced Concrete Structures." NCSU, 2000. http://www.lib.ncsu.edu/theses/available/etd-20000820-165307.
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Seismic building codes, such as the Uniform Building Code (UBC) do not allow the equivalent lateral force (ELF) procedure to be used for structures with vertical irregularities. The UBC defines a structure to be irregular based on the ratio of magnitudes of either strength, stiffness, mass, setback or offset of one floor to that of an adjacent floor. The criteria defining the limits of irregularity are somewhat arbitrary, but are introduced in the code to provide unambiguous, enforceable provisions. The purpose of this study is to quantify the definition of irregular structures for four different vertical irregularities - stiffness, strength, mass and nonstructural masonry infills. A total of 87 building structures with interstory stiffness and strength ratios ranging from 0.09 to 1.89 and 0.27 to 1.07, respectively, and mass ratios of 1.0, 2.5, and 5.0 are considered for a detailed parametric study. The lateral force resisting systems (LFRS) considered are special moment resisting frames and shear walls. These LFRS's are designed based on the forces obtained from the equivalent lateral force procedure. An ELF) analysis. Finally, nonlinear dynamic analysis is performed in order to assess the seismic performance of these buildings. The results show that the restrictions on the applicability of the equivalent lateral force procedure are unnecessarily conservative for irregular structures. Most structures considered in this study, designed on the basis of the ELF approach, perform reasonably well. In some cases, however, there is an initiation of an undesirable collapse mechanism. It is recommended that capacity based criteria in the design phase be appropriately used in the vicinity of the irregularity in order to ensure desired performance and behavior.
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Christodoulou, Christian. "Repair and corrosion management of reinforced concrete structures." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/13577.
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The durability of concrete structures is affected by a number of factors such as environmental exposure, electrochemical reactions, mechanical loading, impact damage and others. Of all of these, corrosion of the reinforcement is probably the main cause for the deterioration of steel reinforced concrete (RC) structures. Corrosion management is becoming increasingly necessary as a result of the growing number of ageing infrastructure assets (e.g. bridges, tunnels etc.) and the increased requirement for unplanned maintenance in order to keep these structures operational throughout their design life (and commonly, beyond). The main RC repair, refurbishment and rehabilitation approaches generally employed can be broadly categorised under a) conventional, b) surface treatments, c) electrochemical treatments and d) design solutions. The overarching aim of this research was to identify the key corrosion management techniques and undertake empirical investigations focused on full-scale RC structures to investigate their long-term performance. To achieve this, individual research packages were identified from the above broad five approaches for repair, replacement and rehabilitation. These were 1) Patch repairs and incipient anodes, 2) Impressed Current Cathodic Protection, 3) Galvanic Cathodic Protection and 4) Hydrophobic treatments. The selection of the above research packages was based on past and present use by the construction industry to repair, refurbish and rehabilitate RC structures. Their contributions may be broadly categorised as i) Investigations on how specific treatments and materials perform, ii) Investigations on the effectiveness of existing methods of measurements and developing alternatives, iii) Changes to the existing theory of corrosion initiation and arrest and iv) Changes to management framework strategies. The key findings from each research package can be summarised as follows: Macrocell activity appears to be a consequence rather than a cause of incipient anode formation in repaired concrete structures, as has previously been presented; ICCP has persistent protective effects even after interruption of the protective current; Discrete galvanic anodes installed in the parent concrete surrounding the patch repair are a feasible alternative to galvanic anodes embedded within the patch repairs of RC structures; Silanes may have a residual hydrophobic effect even after 20 years of service.
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Zhao, Li. "SPATIAL RELIABILITY ANALYSIS FOR CORRODED REINFORCED CONCRETE STRUCTURES." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1479123930240399.
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Aldwaik, Mais M. "Cost Optimization of Reinforced Concrete Highrise Building Structures." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574738135695095.
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Rowan, Andrew George. "Repair and rehabilitation of reinforced concrete harbour structures." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5004.
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Includes bibliographical references.Damage to reinforced concrete infrastructure due to chloride-induced corrosion is widespread throughout the marine environment in South Africa. This thesis is an investigation into four current concrete repair contracts at harbours in the Western Cape. The works are critiqued in terms of repair philosophy and methodology, and recommendations are made for improving practice. A literature review is presented, outlining the relevant background to the chlorideinduced corrosion of reinforcing steel, specifically in the marine environment. Damage assessment tools and techniques are also presented, and the different repair options that are most common in practice are discussed. The contract documentation for the four contracts is reviewed, and it is highlighted that while the bulk of the project specification is identical, the major differences in the documentation from the four contracts are in the quality and level of detail of the construction drawings. The individual repair methods chosen for various concrete elements are described in detail and commented on in terms of concrete durability. Forensic testing results in the forms of chloride profiling and corrosion inhibitor testing at two locations are presented.
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Russell, Justin. "Progressive collapse of reinforced concrete flat slab structures." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28991/.
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In 1968 a relatively small gas exposition on the 18th floor of the Ronan Point tower building resulted in the partial collapse of the structure. This event highlighted that progress collapse may occur to structures under an accidental loading event. Other events, including the bombing of the Murrah federal building in 1993 in Oklahoma, have resulted in the common design requirement that a structure be capable of surviving the removal of a load bearing element. This approach, often referred to as the sudden column loss scenario, effectively ignores the cause of the damage and focuses on the structure’s response afterwards. The refinement of the analysis varies, with options to include the nonlinear and dynamic behaviours associated with extreme events, or to use simplified linear and static models with factors included to account for the full behaviour. Previous research into progressive collapse has highlighted that providing ductility in the connections, and avoiding brittle failures, is important in ensuring the structure maintains integrity after a column loss event. However, the majority of this work has been focused on the behaviour of steel and Reinforced Concrete (RC) frame structures. As flat slab construction is a popular method for many structures, due to the flexibility it offers for layouts and its low storey heights, it is an important to consider flat slab behaviour in more detail. Furthermore, slab elements behave differently to frame structures due to the Alternative Load Paths (ALPs) that can develop after a column loss via two-dimensional bending mechanisms. Additionally, punching shear failure is a known issue due to the thin section depths. This work addresses the issue of the response of RC flat slab structures after a sudden column loss. As previous case studies have demonstrated that brittle failures may lead to progressive collapse of such structures, a complete understanding of the response is required. The nonlinear behaviour of a slab structure, due to both material and geometric factors, is investigated to determine the additional capacity available beyond the usual design limits. Additionally, the dynamic factors involved, primarily due to inertial effects, are also considered. To achieve this, experimental and numerical studies were conducted. A series of 1/3 scale models of slab substructures were constructed to replicate column loss events. Two types of tests were conducted, a static push down test with a support removed and a sudden dynamic column removal case. Displacements, strains and support reactions were recorded throughout, along with cracking patterns. For the dynamic tests a high speed camera was used to obtain the deflection response in the short time period after removal and to observe the formation of cracks. Comparisons between the two cases allowed determination of the dynamic effects on the response of the system. The experimental programme was then replicated using a Finite Element (FE) model. The results taken from the experimental case were used to validate the material and modelling assumptions made during the numerical simulations. This validated model was finally used to investigate a wider range of variables and assess the response of typical structural arrangements, with particular focus on the nonlinear and dynamic factors involved after a sudden column loss. The experimental and numeral investigations demonstrated that after the loss of a column, flat slab structures can maintain integrity due to a change in the load paths away from the removal location. Although in some cases a large amount of flexural damage to the concrete and reinforcement occurred, such effects did not lead to complete failure. However, during the experimental programme some punching shear failures occurred, usually at the corner column locations. From the numerical analysis, shear forces of over twice the fully supported condition occurred as a result of removing a column, which may exceed the designed capacity. Comparisons between a static and dynamic analysis provides information into a suitable Dynamic Amplification Factor (DAF) for use with simplified modelling approaches. Based on the range of structures considered, the maximum increase in deflections as a result of a sudden removal was 1.62 times the static case, this is less than the commonly used factor of 2.0. Additionally, this factor reduces as the nonlinearity increases due to further damage, with a smallest DAF calculated at 1.39. This factor can be reduced further if the column is not removed instantaneously. Finally, the material strengthening effect, due to high strain rates, was considered with the conclusion that as such effects only make a limited increase in the capacity of the slab and may be conservatively ignored. In conclusion, RC flat slab structures are capable of resisting progressive collapse after the loss of a column. This is primarily due to their ability to develop ALPs. However, while flexural damage is usually fairly minimal, progressive punching shear failure is a critical design condition as it may result in a complete collapse. Furthermore, the inertial effects involved after a sudden removal can increase the damage sustained, although current design methods may be over conservative.
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Betaque, Andrew D. "Evaluation of software for analysis and design of reinforced concrete structures." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09192009-040235/.
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Sha'lan, Ahmad Abdulkareem Saker. "Seismic performance of self-centering frames composed of precast post-tensioned concrete encased in FRP tubes." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Fall2009/a_shalan_120709.pdf.
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Thesis (M.S. in civil engineering)--Washington State University, December 2009.Title from PDF title page (viewed on Feb. 4, 2010). "Department of Civil Engineering." Includes bibliographical references (p. 134-135).
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Svecova, Dagmar Carleton University Dissertation Engineering Civil and Environmental. "Serviceability and strength of concrete parking structures reinforced by fibre-reinforced plastics." Ottawa, 1994.
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Nejadi, Shamsaddin Civil & Environmental Engineering Faculty of Engineering UNSW. "Time-dependent cracking and crack control in reinforced concrete structures." Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2005. http://handle.unsw.edu.au/1959.4/22440.
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Due to the relatively low tensile strength of concrete, cracks are inevitable in reinforced concrete structures. Therefore, studying the cracking behaviour of reinforced concrete elements and controlling the width of cracks are necessary objectives both in research and in design. The introduction of higher strength reinforcing steel has exacerbated the problem of crack control. Using higher strength steel, means less steel is required for a given structure to satisfy the strength requirements. The stiffness after cracking is reduced and wider crack widths will occur under normal service loads. Unserviceable cracking may encourage corrosion in the reinforcement and surface deterioration, and may lead to long term problems with durability. Indeed excessive cracking results in a huge annual cost to the construction industry because it is the most common cause of damage in concrete structures. In this study cracking caused by both shrinkage and external loads in reinforced concrete members is examined experimentally and analytically. The mechanisms associated with cracking and the factors affecting the time-varying width and spacing of both direct tension cracks due to restrained shrinkage deformation and flexural cracks due to the combined effects of constant sustained service loads and shrinkage are examined. Laboratory tests on eight fully restrained slab specimens were conducted for up to 150 days to measure the effects of drying shrinkage on the time-dependent development of direct tension cracks due to restrained deformation. The effect of varying the quantity, diameter, and spacing of reinforcing steel bars was studied. In addition, an analytical model previously developed without experimental verification by Gilbert (1992) to study shrinkage cracking was modified and recalibrated. A second series of tests on twenty four prismatic, singly reinforced concrete beams and slabs subjected to monotonically increasing loads or to constant sustained service loads for up to 400 days, were also conducted. The effects of steel area, steel stress, bar diameter, bar spacing, concrete cover and shrinkage were measured and quantified. An analytical model is presented to simulate instantaneous and time-dependent flexural cracking. The tension chord model (Marti et al, 1998) is modified and used in the proposed model to simulate the tension zone of a flexural member and the time-dependent effects of creep and shrinkage are included. The analytical predictions of crack width and crack spacing are in reasonably good agreement with the experimental observations.