Dissertations / Theses: 'Existing Reinforced Concrete'

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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.

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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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Oliveira, João Mário Dias de. "Seismic assessment of existing reinforced concrete buildings." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11661.

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Mestrado em Engenharia Civil
This dissertation aims to the discussion and application of tools and processes which allows to assess the non-linear behaviour of a reinforced concrete structure. When a numerous amount of buildings was built in concrete, in a period when the regulations did not have the design philosophy for the occurrence of earthquakes, it is important to carry out full and e ective structural assessments. Among several possibilities to make the evaluation as, simpli ed, linear analysis and static non-linear analysis, the non-linear dynamic can provide the most approximate numerical behaviour compared to the real one. With the potentialities of the computers, it is possible to run the analysis with this complex simulation using dynamic excitations of real earthquakes. It is made a historical reference of numerical models which simulates the behaviour of materials, and the ones integrated on the analysis are further explored. Is presented the study cases, its assumptions and some procedures that should be applied in structural modelling. The discussion is divided in two groups. On the rst the global analysis is discussed in terms of global behaviour, deformations and progression of forces, and on the second group is referred to the local assessment of structural elements. The local analysis has some comparisons between di erent interpretations of the code and also regarding the Italian code. Is analysed the bond-slip mechanism due to the smooth bars in some elements, which better simulates the global response of the structures.
A presente dissertação visa a discussão e aplicação de ferramentas e processos de veri cação que permitam analisar o comportamento não linear de estruturas em betão armado. Existem actualmente inúmeros edifícios em betão armado, construídos num período em que os regulamentos não previam a ocorrência de sismos, é importante proceder a avaliações estruturais completas e e cazes. Entre várias possibilidades para fazer a avaliação, como simpli cadas, aná- lises lineares, análises estátiocas não-lineares, é a análise dinâmica não-linear que mais aproxima o comportamento numérico ao real. Com as potencialidades numéricas permitidas pelos computadores, é possível prever esse complexo comportamento onde podem ser simuladas excitações dinâmicas de sismos reais. É feita uma referência histórica de modelos numéricos que simulam o comportamento dos materiais, aprofundando os que são integrados na análise. São apresentados os casos de estudo, os pressupostos e alguns procedimentos que devem ser aplicados na modelação estrutural. A discussão dos resultados é separada em dois grupos. No primeiro é feita uma análise global onde se discute o comportamento global, deformações e progressão de forças, e no segundo uma análise local dos elementos estruturais. A análise local é acompanhada de algumas comparações entre diferentes interpretações do código europeu e entre o código italiano. São analisados alguns elementos em relação ao deslize da armadura lisa, representando melhor a resposta das estruturas.

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BOY, SERPIL. "RETROFIT OF EXISTING REINFORCED CONCRETE BRIDGES WITH FIBER REINFORCED POLYMER COMPOSITES." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1078508332.

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Youssef, Maged Ali. "Modeling of existing and rehabilitated reinforced concrete buildings." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0035/NQ66299.pdf.

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Biddah, Ashraf Mahmoud Samy. "Seismic behaviour of existing and rehabilitated reinforced concrete frame connections." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ30074.pdf.

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Yalcin, Cem. "Seismic evaluation and retrofit of existing reinforced concrete bridge columns." Thesis, University of Ottawa (Canada), 1998. http://hdl.handle.net/10393/8902.

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Bridges like other important lifeline structures must remain in service when they are subjected to strong earthquakes. Many existing bridges, especially those built before the 1970s, are vulnerable to seismic damage since a number of deficiencies with regard to low design force levels, inadequate column confinement and lack of shear capacity were discovered during recent earthquakes. Bridge columns are expected to withstand seismically induced inertia forces without a significant loss of strength. This can be achieved in old columns through external retrofitting. Many reinforced concrete bridge columns in California were already retrofitted with steel jackets to enhance flexural ductility and shear resistance. Although this retrofitting technique is highly effective, it is also time consuming and costly, especially in view of the fact that high number of columns are yet to be retrofitted. Therefore, a new retrofitting technique has been developed through experimental research that involves external prestressing of bridge columns for improved deformability and shear strength. The supporting experimental work involved testing of 1485 mm high two 550 mm square and five 610 mm diameter circular cantilever columns. The columns were retrofitted with post-tensioned external hoops and high-strength steel straps at different spacing and stress levels. The results indicated that transverse prestressing of shear-dominant columns improved ductility and changed the mode of behavior from a brittle shear response to a ductile flexural behavior. The research project also included analysis of columns to establish lateral drift demands and capacities for bridge columns in Canada. A comprehensive survey of existing bridges in Canada was conducted to identify and classify common types of existing bridges in terms of their numbers, types, age, and structural and geometric properties. This information proved to be helpful in establishing column drift capacities and demands. A computer software DRAIN-RC, developed for non-linear dynamic analysis of reinforced concrete structures, was used to determine the drift demands of columns under various ground motions. Drift capacities were computed by a computer program COLA, developed by the author. The program COLA uses proper material models such as confinement of core concrete, extension of longitudinal reinforcement in tension, and buckling of re-bars in compression. The decision for retrofitting depended on the capacity of a column when demand exceeded its capacity.

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Bayani, Keivani Shahram. "Seismic evaluation of existing reinforced concrete bridges in Ottawa region." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26357.

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Many existing bridges, especially those built before 1970, were designed with minimum or no seismic considerations. Past experience has shown that such bridges are very vulnerable when subjected to moderate and strong earthquake motions. This was illustrated during the 1989 Loma Prieta, the 1994 Northridge, and the 1995 Kobe earthquakes, when many existing bridge collapsed or were severely damaged. Such a poor performance of the bridges was attributed primarily to the fact that the seismic effects were underestimated in the pre-1970's design practice. In Ottawa region, a great expansion of highway bridges occurred in the 1950's to 1970's, before modern bridge design codes were developed. Statistics show that the number of existing bridges designed according to substandard seismic codes is significantly larger than the number of new, well-designed bridges. Given this, it is essential to develop methods for evaluation and retrofit of existing bridges in order to reduce the risk from seismic actions. In this study, seismic evaluation was conducted to eight bridges located in the Ottawa region and designed according to the pre-1970's bridge codes. In addition, one new bridge, built 1994, was analyzed and was used as a reference case for comparing the performance of older and new bridges. Inelastic models were developed for each bridge and nonlinear dynamic analyses were conducted by using excitation motions compatible with the design spectrum for Ottawa, prescribed by the latest Canadian national code for bridge design. The performance of the bridges was assessed by analyzing the responses represented by curvature ductilities, shear demands, and lateral drifts. The results indicated that the performance of most of the selected bridges is acceptable for the seismic excitations used in this study.

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Yalçin, Cem. "Seismic evaluation and retrofit of existing reinforced concrete bridge columns." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0020/NQ46554.pdf.

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Lu, Ruodan. "Automated generation of geometric digital twins of existing reinforced concrete bridges." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289430.

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The cost and effort of modelling existing bridges from point clouds currently outweighs the perceived benefits of the resulting model. The time required for generating a geometric Bridge Information Model, a holistic data model which has recently become known as a "Digital Twin", of an existing bridge from Point Cloud Data is roughly ten times greater than laser scanning it. There is a pressing need to automate this process. This is particularly true for the highway infrastructure sector because Bridge Digital Twin Generation is an efficient means for documenting bridge condition data. Based on a two-year inspection cycle, there is a need for at least 315,000 bridge inspections per annum across the United States and the United Kingdom. This explains why there is a huge market demand for less labour-intensive bridge documentation techniques that can efficiently boost bridge management productivity. Previous research has achieved the automatic generation of surface primitives combined with rule-based classification to create labelled cuboids and cylinders from point clouds. While existing methods work well in synthetic datasets or simplified cases, they encounter huge challenges when dealing with real-world bridge point clouds, which are often unevenly distributed and suffer from occlusions. In addition, real bridge topology is much more complicated than idealized cases. Real bridge geometries are defined with curved horizontal alignments, and varying vertical elevations and cross-sections. These characteristics increase the modelling difficulties, which is why none of the existing methods can handle reliably. The objective of this PhD research is to devise, implement, and benchmark a novel framework that can reasonably generate labelled geometric object models of constructed bridges comprising concrete elements in an established data format (i.e. Industry Foundation Classes). This objective is achieved by answering the following research questions: (1) how to effectively detect reinforced concrete bridge components in Point Cloud Data? And (2) how to effectively fit 3D solid models in the format of Industry Foundation Classes to the detected point clusters? The proposed framework employs bridge engineering knowledge that mimics the intelligence of human modellers to detect and model reinforced concrete bridge objects in point clouds. This framework directly extracts structural bridge components and then models them without generating low-level shape primitives. Experimental results suggest that the proposed framework can perform quickly and reliably with complex and incomplete real-world bridge point clouds encounter occlusions and unevenly distributed points. The results of experiments on ten real-world bridge point clouds indicate that the framework achieves an overall micro-average detection F1-score of 98.4%, an average modelling accuracy of (C2C) ̅_Auto 7.05 cm, and the average modelling time of merely 37.8 seconds. Compared to the laborious and time-consuming manual practice, the proposed framework can realize a direct time-savings of 95.8%. This is the first framework of its kind to achieve such high and reliable performance of geometric digital twin generation of existing bridges. Contributions. This PhD research provides the unprecedented ability to rapidly model geometric bridge concrete elements, based on quantitative measurements. This is a huge leap over the current practice of Bridge Digital Twin Generation, which performs this operation manually. The presented research activities will create the foundations for generating meaningful digital twins of existing bridges that can be used over the whole lifecycle of a bridge. As a result, the knowledge created in this PhD research will enable the future development of novel, automated applications for real-time condition assessment and retrofit engineering.

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Morbin, Riccardo. "Strategies for Seismic Assessment of Common Existing Reinforced Concrete Bridges Typologies." Doctoral thesis, Università degli studi di Trento, 2013. https://hdl.handle.net/11572/368824.

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This study concerns a new probabilistic framework to evaluate road/railway bridges after an earthquake by means of analytical fragility curves and inspections on the structure. In particular, the assessment is performed on existing reinforced concrete (RC) bridges with a common structural scheme in Italy (multi-span simply supported girder bridges). The framework is set up of 6 steps and each step is investigated. Steps 1 and 2 are a sort of preliminary work before the seismic event occurs: the creation of a database to collect all information about bridges in specific road/railway networks (step 1) and the generation of fragility curves for each bridge (step 2): fragility curves are instruments describing the probability of a structure being damaged beyond a specific damage state for various levels of ground shaking. Since step 2 is a crucial step for the outcomes of the framework, a wide investigation on the generation of fragility curves is presented, considering bridges located in strategic road network points in Veneto region (North-Eastern Italy) and different numerical modellings, in order to evaluate the best seismic vulnerability assessment. Moreover, particular attention is given to retrofit interventions by means of Fiber Reinforced Polymer (FRP) and their effect on bridge seismic vulnerability reduction. The other steps concern activities to carry out after a seismic event, useful for emergency and post-emergency phases. Step 3 regards a method to decide if inspections on bridge are needed in relation to the occurred earthquake seismic intensity; if the seismic intensity measure reaches a specific threshold, step 4 suggests how to perform visual inspections on bridges, under a probabilistic point of view, and to generate the damaged bridge fragility curves. After that, the last two steps try to give useful information to Institution and owners of bridges in order to reach an optimal road/railway network management in post-earthquake phases. Step 5 concerns a quick procedure to decide whether or not allowing traffic over damaged bridges, whereas step 6 gives information about economical benefits coming from a comparison between replace costs and retrofitting costs (considering FRP retrofitting interventions) of damaged bridges. In order to clarify the framework procedure, an example for each step is developed.

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Morbin, Riccardo. "Strategies for Seismic Assessment of Common Existing Reinforced Concrete Bridges Typologies." Doctoral thesis, University of Trento, 2013. http://eprints-phd.biblio.unitn.it/932/1/tesi_PhD_Morbin_2013.pdf.

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This study concerns a new probabilistic framework to evaluate road/railway bridges after an earthquake by means of analytical fragility curves and inspections on the structure. In particular, the assessment is performed on existing reinforced concrete (RC) bridges with a common structural scheme in Italy (multi-span simply supported girder bridges). The framework is set up of 6 steps and each step is investigated. Steps 1 and 2 are a sort of preliminary work before the seismic event occurs: the creation of a database to collect all information about bridges in specific road/railway networks (step 1) and the generation of fragility curves for each bridge (step 2): fragility curves are instruments describing the probability of a structure being damaged beyond a specific damage state for various levels of ground shaking. Since step 2 is a crucial step for the outcomes of the framework, a wide investigation on the generation of fragility curves is presented, considering bridges located in strategic road network points in Veneto region (North-Eastern Italy) and different numerical modellings, in order to evaluate the best seismic vulnerability assessment. Moreover, particular attention is given to retrofit interventions by means of Fiber Reinforced Polymer (FRP) and their effect on bridge seismic vulnerability reduction. The other steps concern activities to carry out after a seismic event, useful for emergency and post-emergency phases. Step 3 regards a method to decide if inspections on bridge are needed in relation to the occurred earthquake seismic intensity; if the seismic intensity measure reaches a specific threshold, step 4 suggests how to perform visual inspections on bridges, under a probabilistic point of view, and to generate the damaged bridge fragility curves. After that, the last two steps try to give useful information to Institution and owners of bridges in order to reach an optimal road/railway network management in post-earthquake phases. Step 5 concerns a quick procedure to decide whether or not allowing traffic over damaged bridges, whereas step 6 gives information about economical benefits coming from a comparison between replace costs and retrofitting costs (considering FRP retrofitting interventions) of damaged bridges. In order to clarify the framework procedure, an example for each step is developed.

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Mola, Elena. "Criteria for the seismic vulnerability reduction of existing irregular reinforced concrete structures." Grenoble INPG, 2007. http://www.theses.fr/2007INPG0019.

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Le travail de recherche décrit est une contribution au développement de outils pour l'évaluation de la vulnérabilité des structures existantes aux événements sismiques et pour la prise de décision quant à la conception de stratégies de renforcement, notamment en cas d'irrégularité. Premièrement, on a clarifié autant que possible les caractéristiques les plus importantes du comportement sismique des structures irrégulières existantes ; deuxièmement, basé sur la leçon apprise de l'analyse des données expérimentales, on a proposé des critères pour réduire la vulnérabilité sismique de cette classe de structures en concevant des interventions efficaces de réhabilitation. Le travail a été largement basé sur l'exploitation des données dérivant d'une campagne expérimentale étendue effectuée dans le cadre du projet de recherche européen 'SPEAR'. Plusieurs moyens ont été employés à cet effet, complétant l'approche expérimentale : realisation d'un modèle numérique aux éléments finis, application des procédures simplifiées d'évaluation sismique, utilisation de l'analyse modale non linéaire de Karhunen-Loeve
The research is a contribution to the development of tools and criteria for the seismic assessment and retrofitting of existing reinforced concrete structures, in particular plan-wise irregular ones. Ln fact, the 'capacity design' method, based on the rationale of the equal displacernent rule and the central role of ductility, and usually employed for the design of new structures, does not automatically extend to existing irregular structures. The work is thoroughly based on a large scale experimental activity carried out in the framework of the EC-funded project SPEAR (Seismic Performance Assessment and Rehabilitation) and consisting of a series of pseudodynamic tests on a full-size plan-wise irregular three storey frame structure, bath in the as-built and in two different retrofitted configurations. Based on the experimental data, the research attempted at first at clarifying the basic features of the seismic response of such structures ; following to that, the proposed criteria for the reduction of their seismic vulnerability and for the design of effective rehabilitation interventions were presented. To this end, the experimental approach was complemented by the numerical one, with the creation of a numerical model into a finite element structural analysis software and the application of the Karhunen-Loeve nonlinear modal analysis method

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Magnanini, Nicola. "Seismic retrofit of a reinforced concrete building placed in L'Aquila." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4778/.

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Valentini, Giacomo. "Seismic vulnerability assessment and retrofit using BRB of an existing reinforced concrete building." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.

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La tesi verte su un’analisi di vulnerabilità sismica di un edificio esistente ed una conseguente ipotesi di adeguamento strutturale. L’edificio è stato realmente sottoposto ad un adeguamento sismico che, tuttavia, è diverso da quello proposto nell'elaborato di tesi. Lo studio di ingegneria Open Project è la società incaricata di eseguire i lavori. Il comportamento dell’edificio è stato valutato mediante la creazione di un modello della struttura su un software ad elementi finiti. I dati introdotti nel modello sono stati messi a disposizione da Open Project e sono presi dalle tavole tecniche originali. Le verifiche eseguite sul modello sono state le seguenti: verifiche ai carichi verticali, verifiche allo stato sismico di salvaguardia della vita e allo stato sismico di limite del danno. Le verifiche non sono state superate. La soluzione proposta è stata di inserire degli elementi dissipativi diagonali all’interno dei telai. I dissipatori sono prodotti dalla ditta FIP Industriale e sono della tipologia denominata BRAD. La procedura di dimensionamento dei dispositivi antisismici ha richiesto la definizione del modulo elastico dell’elemento controvento da inserire nel software di calcolo. Posizionati i dissipatori è stata effettuata un’analisi dinamica modale della struttura per verificare che lo spostamento limite di interpiano allo stato limite di danno soddisfacesse i requisiti da normativa. In seguito il modello è stato sottoposto ad un’analisi pushover per verificare la condizione dei dissipatori allo stato limite ultimo. Questa seconda analisi si è resa necessaria per verificare che lo spostamento in sommità dei portali non conducesse il dispositivo BRAD ad eccedere il suo massimo allungamento possibile compromettendone la funzionalità. L’iter di dimensionamento dei dispositivi descritto sopra ha richiesto alcuni tentativi prima di portare ad ottenere un numero adeguato di dispositivi di rigidezza corretta che soddisfacesse le due condizioni imposte.

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Bayraktar, Atilla. "Detailed Evaluation Of An Existing Reinforced Concrete Building Damaged Under Its Own Weight." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613230/index.pdf.

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DETAILED EVALUATION OF AN EXISTING REINFORCED CONCRETE BUILDING DAMAGED UNDER ITS OWN WEIGHT Bayraktar, Atilla M.Sc., Department of Civil Engineering Supervisor: Prof. Dr. Ahmet Yakut May 2011, 130 pages A significant part of the Turkey&rsquo
s building inventory consists of reinforced concrete frame structures. In addition to that a big part of the existing building inventory in Turkey shows insufficiency in seismic performance damage or failure of structures under their own loads has also been observed. The failure of Zü
mrü
t Apartment building that occurred in 2004 in Konya and resulted in the death of 92 people brings the necessity of researches on robustness and reserve capacities of the buildings under gravity loading to front. In the context of this thesis, the event in Konya that has resulted in the crushing of four columns in Dostlar Building Complex is studied. After the occurrence of the event, the building was visited, plans of existing condition were prepared and pre-assessment was performed. Original plans of the building, strength test results of the concrete samples and reinforcement detection results were obtained. The reasons behind the crushing of the columns have been investigated through a series of analyses based on a number of possible hypotheses. After modeling the building in SAP2000 program, demand-capacity ratios are calculated. Nonlinear behavior of the structure is determined by incremental static pushover analysis and the seismic performance of the building is evaluated by nonlinear procedure described in 2007 Turkish Earthquake Code. To determine the nonlinear behavior under gravity loading and collapse mechanism, incremental vertical pushover analysis is performed.

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Carriere, Jean-Michel. "Seismic retrofit of existing reinforced concrete moment resisting frame structures using diagonal prestressing." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27449.

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The national building code of Canada (NBCC) has been under constant evolution since its first issue in 1941. Over the years, knowledge related to structural engineering and more specifically seismic response has continued to evolve through research and field investigations. Recently, the 2005 NBCC has been made available with a new perspective on seismic design, including uniform hazard spectra provided for each city for static and dynamic analyses. Due to a greater understanding of seismic response of structures and the Canadian seismicity, the NBCC has increased the values of elastic base shears over the years. Between the 1970 and 2005 editions of NBCC, the elastic design base shear has increased by a factor as high as 2.6. A structure designed in 1970, if subjected to 2005 NBCC compatible design earthquake record would potentially be labeled as seismically deficient and fail under code specified loads. Multiple technologies currently exist to retrofit seismically deficient structures. The purpose of this research is to explore the possibilities of using diagonal prestressing, in various configurations, to increase structural stiffness and decrease lateral drift demands under seismic loading. Shallouf (2005) successfully demonstrated experimentally that a 1 bay, 1 storey R/C frame with masonry infill panels, designed based on the ACI 318-1963 building code, hence seismically deficient, could be retrofitted with prestressed cables to reduced lateral drift. In addition, analytical modeling of the 1 storey frame and analysis of a 5 storey structure in a high seismic region (i.e. Vancouver) were used to illustrate the effectiveness of the approach. This analytical model was successful in reducing lateral drift under various prestressing patterns. The objective of this research is to continue investigating the effectiveness of the retrofit methodology for structures in two different seismic zones, such as Vancouver and Ottawa. Also, it is examined for buildings with different heights. Structures varying between five and fifteen storeys are analyzed. The results indicate the effectiveness of high-strength prestressing cables as lateral bracing elements, while the effect of prestressing the cables changing with the dynamic characteristics of the building and their interaction with the frequency of the exciting force, i.e., earthquake record.

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Cavallari, Giulia. "Pushover analysis of an existing reinforced concrete bridge:Jamboree Road Overcrossing in Irvine, California." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3300/.

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The work for the present thesis started in California, during my semester as an exchange student overseas. California is known worldwide for its seismicity and its effort in the earthquake engineering research field. For this reason, I immediately found interesting the Structural Dynamics Professor, Maria Q. Feng's proposal, to work on a pushover analysis of the existing Jamboree Road Overcrossing bridge. Concrete is a popular building material in California, and for the most part, it serves its functions well. However, concrete is inherently brittle and performs poorly during earthquakes if not reinforced properly. The San Fernando Earthquake of 1971 dramatically demonstrated this characteristic. Shortly thereafter, code writers revised the design provisions for new concrete buildings so to provide adequate ductility to resist strong ground shaking. There remain, nonetheless, millions of square feet of non-ductile concrete buildings in California. The purpose of this work is to perform a Pushover Analysis and compare the results with those of a Nonlinear Time-History Analysis of an existing bridge, located in Southern California. The analyses have been executed through the software OpenSees, the Open System for Earthquake Engineering Simulation. The bridge Jamboree Road Overcrossing is classified as a Standard Ordinary Bridge. In fact, the JRO is a typical three-span continuous cast-in-place prestressed post-tension box-girder. The total length of the bridge is 366 ft., and the height of the two bents are respectively 26,41 ft. and 28,41 ft.. Both the Pushover Analysis and the Nonlinear Time-History Analysis require the use of a model that takes into account for the nonlinearities of the system. In fact, in order to execute nonlinear analyses of highway bridges it is essential to incorporate an accurate model of the material behavior. It has been observed that, after the occurrence of destructive earthquakes, one of the most damaged elements on highway bridges is a column. To evaluate the performance of bridge columns during seismic events an adequate model of the column must be incorporated. Part of the work of the present thesis is, in fact, dedicated to the modeling of bents. Different types of nonlinear element have been studied and modeled, with emphasis on the plasticity zone length determination and location. Furthermore, different models for concrete and steel materials have been considered, and the selection of the parameters that define the constitutive laws of the different materials have been accurate. The work is structured into four chapters, to follow a brief overview of the content. The first chapter introduces the concepts related to capacity design, as the actual philosophy of seismic design. Furthermore, nonlinear analyses both static, pushover, and dynamic, time-history, are presented. The final paragraph concludes with a short description on how to determine the seismic demand at a specific site, according to the latest design criteria in California. The second chapter deals with the formulation of force-based finite elements and the issues regarding the objectivity of the response in nonlinear field. Both concentrated and distributed plasticity elements are discussed into detail. The third chapter presents the existing structure, the software used OpenSees, and the modeling assumptions and issues. The creation of the nonlinear model represents a central part in this work. Nonlinear material constitutive laws, for concrete and reinforcing steel, are discussed into detail; as well as the different scenarios employed in the columns modeling. Finally, the results of the pushover analysis are presented in chapter four. Capacity curves are examined for the different model scenarios used, and failure modes of concrete and steel are discussed. Capacity curve is converted into capacity spectrum and intersected with the design spectrum. In the last paragraph, the results of nonlinear time-history analyses are compared to those of pushover analysis.

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Boylu, Mert Aktaş Engin. "A Benefit/Cost Analysis For The Seismic Rehabilitation On Existing Reinforced Concrete Buildings in İzmir/." [s.l.]: [s.n.], 2005. http://library.iyte.edu.tr/tezler/master/yapimekanigi/T000333.pdf.

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Thesis (Master)--İzmir Institute of Technology, İzmir,2005.
Keywords: Benefit-cost analysis, seismicity, seismic safety, rehabilitation, damage estimation. Includes bibliographical references (leaves.81-83).

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De, Jager Charl. "A critical appraisal of existing models for nonlinear finite element analysis of reinforced concrete response." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20052.

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Thesis (MScEng)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: This study entails the appraisal of the constitutive models available for the non linear finite element analysis of reinforced concrete, using the DIANA finite element package and following generally accepted guidelines for non linear finite element analyses. The constitutive models considered are plasticity and total strain based (fixed and rotating crack) models. The appraisal consists of the analysis of various experiments performed on reinforced concrete beams that are governed by compressive, shear and tensile dominated failures. The investigation is not limited to the accuracy of the results obtained using these models but also of the consistency of the results obtained with regard to various mesh types and sizes, as well as a study of the individual influence of several material parameters. The intention of the study was to provide the reader with an indication of the performance capacity (accuracy and consistency) of the available constitutive models, where the notion of the use of the results obtained from non linear finite element analyses for design purposes is considered. The results obtained were varied. The models performed reasonably well in the compressive and tension dominated studies, with the importance of accurate material parameters being emphasized especially for the more advanced cementitious materials investigated. The total strain rotating crack model also showed a proclivity of simulating incorrect failure modes as well as exhibiting reluctance towards stress redistribution. All models used for the shear dominated study yielded mostly inaccurate and inconsistent results, but it was found that the four node quadrilateral element with selective reduced integration performed the best. The plasticity model did not capture shear failure well, and convergence was often not attained. The constant shear retention factor of the total strain fixed crack model was found to yield more detailed response curves for the smaller mesh sizes. The results of the tension dominated beams inspired more confidence in the models as quite accurate values were attained, especially by the plasticity model used. The ability of the available models to simulate realistic structural behaviour under various failure modes is very limited, as is evident from the results obtained. The development of a more advanced and robust model is required, which can provide consistently accurate results and failure modes, and even ‘anticipate’ potential failure modes not considered by the user.

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20

Zimos, D. K. "Modelling the post-peak response of existing reinforced concrete frame structures subjected to seismic loading." Thesis, City, University of London, 2017. http://openaccess.city.ac.uk/18531/.

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Structural members of reinforced concrete (R/C) buildings designed according to older, less stringent seismic codes are often vulnerable to shear or flexure-shear failure followed by axial failure. Thus, such substandard R/C structures are susceptible to vertical collapse, which pertains to the exceedance of vertical resistance of columns and connecting beams and can lead to the whole structure – or a substantial part of it – undergoing collapse. The largest database of shear and flexure-shear critical R/C columns cycled well beyond the onset of shear failure and/or up to the onset of axial failure is compiled and empirical relationships are developed for key parameters affecting the response of such members after the initiation of shear failure. A novel shear hysteresis model is proposed employing these relationships, based on experimental observations that deformations after the onset of shear failure tend to concentrate in a specific member region. A computationally efficient finite element model of the member-type is proposed, using the above shear hysteretic model and combining it with displacements arising from flexural and bond-slip deformations to get the full lateral force-lateral displacement response. It accounts for the interaction between flexural and shear deformations inside the potential plastic hinges, the distribution of flexural and shear flexibility along the element, as well as the location and extent of post-peak shear damage, without relying on assumptions about the bending moment distribution and avoiding shortcomings of previous beam-column models pertinent to numerical localisation. Thus, the full-range hysteretic response of substandard R/C elements can be predicted up to the onset of axial failure subsequent to shear failure with or without prior flexural yielding, while simultaneously accounting for potential flexural and anchorage failure modes. The proposed model is implemented in a finite element structural analysis software and its predictive capabilities are verified against quasi-static cyclic and shake-table test results of column and frame specimens. The model is shown to be sufficiently accurate not only in terms of total response, but more crucially in terms of individual deformation components. Overall, it is believed that the accuracy, versatility and simplicity of this model make it a valuable tool in seismic analysis of complex substandard R/C buildings. An experimental investigation of shear and flexure-shear critical R/C elements is carried out with the aim of independently validating the beam-column model. Furthermore, an opportunity is provided to verify the model’s underlying assumptions, which is of paramount importance for the reliability of its analytical predictions. The experiments were designed in such a manner as to investigate the effect of vertical load redistribution from axially failing members on the lateral post-peak response of neighbouring columns.

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21

Smiroldo, Francesco. "Increasing the seismic resilience of existing reinforced concrete framed structures by using timber-based panels." Doctoral thesis, Università degli studi di Trento, 2022. https://hdl.handle.net/11572/355186.

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In this Thesis, an intervention system applicable to existing reinforced concrete (RC) framed buildings is presented. The main purpose of the intervention is to improve the seismic behaviour of such buildings using cross-laminated timber (CLT) panels without modifying the original concrete structural system. The intervention proposed can also be implemented to reduce the energy consumption of buildings. Furthermore, the intervention can be partially prefabricated in order to speed up execution and reducing labour costs. The need to intervene on existing concrete buildings to improve their seismic behaviour arises from: a) this type of buildings represents a large percentage of the built heritage of many Countries; b) most of these structures were designed considering vertical loads only. Specifically, the built heritage is often characterised by details and construction techniques that deviate significantly from those required for new structures. Recent earthquakes have shown that, under seismic actions of smaller magnitude than those considered for new buildings, past construction practices frequently involve unforeseen damage or the activation of brittle mechanisms of collapse. The main critical issues of this kind of structure are: the detachment and the collapse of the infills; the failure of the beam-column joints; the shear failure of the concrete elements due to the interaction with the infills; the activation of soft-storey mechanisms as a consequence of torsional motions or concentration of lateral deformations in a single storey. To reduce the seismic vulnerability of these structures, a retrofit solution was proposed. The solution sees the connection of structural CLT panels to the existing RC elements through dissipative steel fasteners. The main goal of this intervention is to improve the in-plane response of the frames. Specifically, two alternative intervention configurations with different levels of invasiveness were studied. With reference to an isolated one-storey one-bay frame, the most invasive configuration, named RC–TP (Reinforced Concrete–Timber Panels), consists in the removal of one or more original masonry wythes and in their replacement with a CLT panel. The panel is inserted into the space originally occupied by the infill and is connected to the RC frame through a timber subframe and metal dowel-type fasteners. The least invasive configuration, named RC–TPext (Reinforced Concrete–external Timber Panels), consists in the arrangement of the CLT panel from the outside without removing the original infill. Vertical cuts at the lateral edges of the masonry infill prevent the infill, which in case of in-plane actions responds as a strut, from transferring additional forces to the columns and causing their collapse in shear. Because in RC–TP the panel is inserted inside the frame, it can also contribute to resist vertical actions if the seismic action damages the structural elements or increases the vertical loads. In addition, the replacement of the masonry infills with CLT panels results in reduced seismic masses and wall thickness. RC–TP has therefore a greater impact on the building and requires more burdensome labours, while RC–TPext leads to shorter execution time and less disturbance to the occupants. In the work presented here, numerical analyses and experimental tests were conducted to investigate the seismic response of existing RC frames both in pre- and post-intervention configurations. Specifically, finite element models comprising bare, masonry-infilled and retrofitted one-storey one-bay frames were subjected to nonlinear static and dynamic analyses by adopting numerical strategies with different levels of refinement. An extensive numerical campaign was devoted to investigating and optimising the behaviour of the intervention system on the basis of several aspects, such as the state of load, the mechanical and geometrical properties of the original system, the presence of weak beam-column joints, and the influence of openings. These analyses enabled the definition of a few “design rules” to guide the implementation of the retrofit system. Through the definition of “simplified” modelling approaches, the intervention system was also applied to entire case-study structures which were subjected to nonlinear static analyses. An analytical approach able to reproduce the response of isolated frames retrofitted with the RC-TP solution was developed to facilitate the pre-design of the intervention. This approach does not require the use of numerical analyses and permits to analyse multiple configurations with small amounts of output data. In the final phase, a set of four full-scale one-storey one-bay frames representative of the Italian heritage were tested by applying in-plane quasi-static cyclic loading up to a collapse condition. The four specimens comprised: a) masonry infilled frame; b) RC–TP retrofit 1; c) RC–TP retrofit 2; d) RC–TPext retrofit 3. The results obtained indicate that the proposed retrofit intervention can be used to significantly improve the seismic behaviour of existing RC frames by increasing both displacement and resistance capacities and by favouring the development of ductile mechanisms of collapse.

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Duzce, Zeynep. "Performance Evaluation Of Existing Medium Rise Reinforced Concrete Buildings According To 2006 Turkish Seismic Rehabilitation Code." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607834/index.pdf.

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Linear elastic and nonlinear analysis procedures of 2006 Turkish Seismic Rehabilitation Code are applied to medium rise reinforced concrete buildings. In this study, four storey residential buildings are designed according to the 1998 and 1975 Turkish Seismic Design Codes, and the analysis procedures are verified on these case studies. In addition to these buildings, the analysis procedures are tested on an existing school building before and after retrofitting. The assessment procedures employed in the 2006 Turkish Seismic Rehabilitation Code are based on linear elastic analysis (equivalent lateral load method, mode superposition method)
non-linear analysis (pushover analysis with equivalent lateral load method and mode superposition method) and non-linear time history analysis. In this study, linear elastic analysis with equivalent lateral loads and non-linear static analysis (pushover analysis) with equivalent lateral loads are investigated comparatively. SAP2000 software is used for pushover analysis
however the plastic rotation values obtained from SAP2000 are not used directly but defined according to the code procedures. Post-elastic rotations at yielding sections are transferred to Excel and the corresponding strains are calculated from these rotations by Excel Macro. These strains are compared with strain limits described in the 2006 Turkish Seismic Rehabilitation Code to obtain the member performances. In the linear elastic procedure, structural analysis is performed also by SAP2000 to obtain the demand values, whereas the capacity values are calculated by another Excel Macro. With these demand and capacity values, corresponding demand to capacity ratios are calculated and compared with demand to capacity ratio limits described in 2006 Turkish Seismic Rehabilitation Code to obtain the member performances. Global performances of the buildings are estimated from the member performances and from the inter-storey drifts for both two methods. The results are compared to each other, and critically evaluated.

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Dogan, Onur. "Multistage Seismic Assessment Methods For Existing Reinforced Concrete Buildings And Their Applicability For Retrofitting Cost Estimation." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615470/index.pdf.

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When the huge building stock in Turkey is considered, it is practically impossible to carry out detailed structural analyses for all of the buildings. In order to cope with the seismic safety evaluation of a large number of existing buildings, it is necessary to use simplified techniques, which can predict the seismic vulnerability of the existing buildings in a relatively short time. The comprehensive structural data compiled for the 48 different reinforced concrete buildings contain full information on their structural characteristics before and after retrofitting and are used in this study. The first basic goal of the study is to develop a procedure through which the building stock under consideration can be classified as &ldquo
safe&rdquo
or &ldquo
unsafe&rdquo
according to the current Turkish Seismic Code. The classification procedure is based on discriminant analysis. The cross-sectional area of the load-bearing members of a building and its preliminary assessment score are selected as the discriminator variables. The second and ultimate basic goal of the study is to propose a method through which the minimum retrofitting cost for satisfying the provisions of the Turkish Seismic Code can be estimated. A quick and uncostly assessment of retrofitting cost estimates based on the procedure described in this thesis will provide a useful input for decisions concerning whether a seismically &ldquo
unsafe&rdquo
building should be rebuilt or retrofitted. Such a situation will save time, labor and money, when it is used for the evaluation of building stocks involving large number of buildings and also in urban transformation operations.

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Liel, Abbie B. "Assessing the collapse risk of California's existing reinforced concrete frame structures : metrics for seismic safety decisions /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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Wang, Naiyu. "Reliability-based condition assessment of existing highway bridges." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34835.

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Condition assessment and safety verification of existing bridges and decisions as to whether bridge posting is required are addressed through analysis, load testing, or a combination of methods. Bridge rating through structural analysis is by far the most common procedure for rating existing bridges. The American Association of State Highway and Transportation Officials (AASHTO) Manual for Bridge Evaluation (MBE), First Edition permits bridge capacity ratings to be determined through allowable stress rating (ASR), load factor rating (LFR) or load and resistance factor rating (LRFR); the latter method is keyed to the AASHTO LRFD Bridge Design Specifications, which is reliability-based and has been required for the design of new bridges built with federal findings since October, 2007. A survey of current bridge rating practices in the United States has revealed that these three methods may lead to different ratings and posting limits for the same bridge, a situation that carries serious implications with regard to the safety of the public and the economic well-being of communities that may be affected by bridge postings or closures. To address this issue, a research program has been conducted with the overall objective of providing recommendations for improving the process by which the condition of existing bridge structures is assessed. This research required a coordinated program of load testing and finite element analysis of selected bridges in the State of Georgia to gain perspectives on the behavior of older bridges under various load conditions. Structural system reliability assessments of these bridges were conducted and bridge fragilities were developed for purposes of comparison with component reliability benchmarks for new bridges. A reliability-based bridge rating framework was developed, along with a series of recommended improvements to the current bridge rating methods, which facilitate the incorporation of various in situ conditions of existing bridges into the bridge rating process at both component and system levels. This framework permits bridge ratings to be conducted at three levels of increasing complexity to achieve the performance objectives, expressed in the terms of reliability, that are embedded in the LRFR option of the AASHTO Manual of Bridge Evaluation. This research was sponsored by the Georgia Department of Transportation, and has led to a set of Recommended Guidelines for Condition Assessment and Evaluation of Existing Bridges in Georgia.

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Sentosa, Bastian Okto Bangkit. "Assessing the structural elements of reinforced concrete buildings by using dynamic measurements." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAA008/document.

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Les applications des mesures dynamiques sur les bâtiments existants sont nombreuses : vérification de la vulnérabilité sismique des structures qui ont été construites avant l’apparition des règles parasismiques ; auscultation de la capacité des structures en situation post-sismique ou après des modifications au voisinage (creusement d’un tunnel à côté ou démolition des immeubles voisins par exemple). A l’heure actuelle, ce type de mesure permet le diagnostic d’une structure à l’échelle globale (toute la structure) alors que l’identification et la localisation des endommagements à l’échelle locale (chaque élément de la structure) restent encore à approfondir. Dans le cadre de cette thèse, le diagnostic à l’échelle locale des structures sera étudié. Cette thèse s’insère dans un contexte national de réévaluation des structures existantes du fait du nombre important de bâtiments à réhabiliter. Au sein du LOCIE, nous pensons que le comportement global des bâtiments est certes influencé par l’interaction sol-structure mais au moins autant par la qualité des connexions des éléments de structures entre eux. Il existe un besoin de qualification de ces connexions dont la variabilité du comportement peut provenir aussi bien de défauts de mise en œuvre (positionnement des armatures,…) que du vieillissement des structures. L’objectif principal de cette thèse est de proposer une méthode pouvant caractériser les liaisons entre les éléments de structure afin de pouvoir caler un modèle numérique. Ces caractérisations devaient être possibles à partir de mesures de sollicitations dynamiques. Une première étape de ce travail consistera à caractériser sur une partie de structure une liaison. Cela sera fait sur un portique en béton armé. Par la suite, cette méthode sera adaptée à une caractérisation au sein d’une structure de bâtiment. Pour cela nous ferons appel à la notion de sous-modèle. Un modèle numérique sera associé à cette méthode aussi bien sur la connexion simple que sur l’ensemble du bâtiment. Le travail de thèse s’appuiera sur l’utilisation et le développement de techniques concernant le traitement des données dynamiques ; la réduction de modèles ; l’expérimentation en laboratoire (échelle locale et échelle d’un élément de structure) et la modélisation numérique par éléments finis à plusieurs échelles
There are many of the examples of dynamics measurements applications in the existing building: verification of structural seismic vulnerability, which was constructed before the earthquake building code; auscultation of structural capacity in post-earthquake situation or after modification in surround environment (Excavation of tunnel or demolition the neighbour buildings for example). Currently, this measurement type enables the diagnosis a structure in global scale (a whole structure) while identification and localization of damage in local scale (each elements of the structure) remains to be explored. In this dissertation, diagnosis in locale scale will be studied. This study is significant for its contribution to the national reassessment of existing structures where there is the large number of buildings to be rehabilitated

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Ozturk, Ismail. "A Comparative Assessment Of An Existing Reinforced Concrete Building By Using Different Seismic Rehabilitation Codes And Procedures." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608036/index.pdf.

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Lateral load carrying capacities of reinforced concrete structures which are designed by considering only gravity loads or according to outdated earthquake codes can be insufficient. The most important problem for these buildings is the limited ductility of the frame elements. How to evaluate the performance of an existing structure and to what level to strengthen it had been major concerns for structural engineers. Recent earthquakes which occurred in the Marmara Region in the last decade have increased the number of seismic assessment projects drastically. However, there was no special guideline or code dealing with the assessment of existing buildings. In order to have uniformity in assessment projects, a new chapter has been included in the revised Turkish Earthquake Code (2006). In this study, the existing and retrofitted conditions of a reinforced concrete building were assessed comparatively by employing linear and nonlinear assessment procedures according to different seismic rehabilitation codes. The study was carried out on a six storey reinforced concrete telephone exchange building. Although there was no damage in the structure due to the recent earthquakes that occurred in the Marmara Region, the building was assessed and retrofitted in 2001 by using equivalent lateral load analysis results. The results of linear and nonlinear assessment procedures performed in the scope of this thesis, were also compared with the assessment results of this previous study. In the nonlinear assessment procedures, pushover analysis results were used. In addition to comparison of the assessment procedures, efficiency of a widely used approximate pushover method was also investigated.

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Al-Majidi, Mohammed Kadhim Haloob. "Development of Fibre Reinforced Geopolymer Concrete (FRGC) cured under ambient temperature for strengthening and repair of existing structures." Thesis, University of Brighton, 2017. https://research.brighton.ac.uk/en/studentTheses/13f703df-e33a-42d7-ad73-8511390fd582.

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Most of the previous research on plain and fibre reinforced geopolymer concrete (FRGC) has concerned on the properties of geopolymer mixtures hardened under heat curing conditions, which is a severe limitation for on-site, cast-in-place applications. This study focuses on the material and structural properties of novel fibre reinforced geopolymer concretes cured under ambient temperature. The overall aim of the study was to develop and test a more environmentally sustainable concrete material with improved structural characteristics, which utilises waste rather than primary mineral products, suitable for cast-in-place applications and for the structural strengthening of existing buildings. In the first part of this thesis, the material behaviour of FRGC cured under ambient temperature was examined. Initially, the work identified the role of various parameters which may affect material compressive strength, in order to enhance overall performance. In addition, the mechanical and microstructural properties of geopolymer mortar with different slag contents and variant silica fume types (densified, undensified and slurry) were assessed. Following this, the effect of slag content and silica fume particle size on the properties of steel fibre reinforced geopolymer composites (SFRGC) was examined. The optimum FRGC mixtures were further investigated in term of its durability characteristics and mechanical properties, in order to provide strain hardening characteristics. In the examined mixes, different fibre types, aspect ratios, and volume fractions, and its comparison with Portland cement based conventional concrete, have been assessed and appropriate mixtures have been identified with multiple fine cracks and strain hardening in tension. In the final part of the thesis, the structural behaviour of FRGC is examined at larger scale application. PVA and steel fibre reinforced geopolymer concrete mixtures were used as strengthening and repair materials for the protection of steel bars in a new material layer, and for subsequent improvement of the flexural strength of existing beams. Large scale beams strengthened with additional FRGC layers reinforced with steel bars have been examined. Also, an additional investigation was conducted in beams where part of the concrete cover at various depths was replaced by FRGC. In all the examined cases respective beams with conventional concrete were examined in order to evaluate the efficiency of the proposed technique. Accelerated corrosion tests were performed using the induced current technique by applying a nominal 300 mA constant anodic current. The results of this investigation showed significant improvements in the structural performance of the examined beams following strengthening or repair with FRGC. The outcomes of the experimental work indicate that FRGC considerably enhanced both the flexural strength capacity and the durability of strengthened and repaired reinforced concrete elements.

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Gunel, Orhun Ahmet. "Influence Of The Shear Wall Area To Floor Area Ratio On The Seismic Performance Of Existing Reinforced Concrete Buildings." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615678/index.pdf.

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An analytical study is performed to evaluate the influence of shear wall area to floor area ratio on the behavior of existing mid-rise reinforced concrete buildings under earthquake loading. The seismic performance of five existing school buildings with shear wall ratios between 0.00% and 2.50% in both longitudinal and transverse directions and their strengthened counterparts are evaluated. Based on the structural properties of the existing buildings, additional buildings with varying shear wall ratios are designed. Consequently, twenty four buildings with different floor plans, number of stories, cross-sectional properties of the members and material strengths are acquired. Nonlinear time-history analyses are performed for all buildings by utilizing the software program, SAP2000 v14.2.0. under seven different ground motion records. The results indicated that roof drifts and plastic deformations reduce with increasing shear wall ratios, but the rate of decrease is lower for higher shear wall ratios. Buildings with 1.00% shear wall ratio have significantly lower roof drifts and plastic deformations when compared to buildings with 0.00% or 0.50% shear wall ratio. Roof drifts and plastic deformations are minimized when the shear wall ratio is increased to 1.50%. After this limit, addition of shear walls has only a slight effect on the seismic performance of the analyzed buildings.

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Bagge, Niklas. "Structural assessment procedures for existing concrete bridges : Experiences from failure tests of the Kiruna Bridge." Doctoral thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63000.

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Assessing existing bridges is an important task in the sustainable management ofinfrastructure. In practice, structural bridge assessments are usually conducted usingtraditional and standardised methods, despite knowledge that these methods oftenprovide conservative estimates. In addition, more advanced methods are available, suchas nonlinear finite element (FE) analysis, that are used for research purposes and cansimulate the structural behaviour of bridges more accurately. Therefore, it would beuseful to develop practical and reliable procedures for refined assessments using theseadvanced techniques.Focusing on the ultimate load-carrying capacity of existing concrete bridges, this thesispresents a procedure for structural assessments. The fundamental idea is to improve theassessment successively, as necessary to predict bridges’ structural behaviour adequately.The procedure involves a multi-level assessment strategy with four levels of structuralanalysis, and an integrated framework for safety verification. At the initial level (Level 1)of the multi-level strategy, traditional standardised methods are used, no failures arecovered implicitly in the structural analysis and action effects are verified using localresistances calculated using analytical models. In the subsequent enhanced levels (Levels2 – 4), nonlinear FE analysis is used for stepwise integration of the verification of flexural,shear-related and anchorage failures into the structural analysis. The framework for safetyverifications includes partial safety factor (PSF), global resistance safety factor (GRSF) andfull probabilistic methods. Within each of these groups, verifications of desired safetymargins can be conducted with varying degrees of complexity.To demonstrate and evaluate the proposed structural assessment procedure, comparativestudies have been carried out, based on full-scale tests of a prestressed concrete bridge.This was the Kiruna Bridge, located in the northernmost city in Sweden, which was duefor demolition as part of a city transformation project, necessitated by large grounddeformations caused by the large nearby mine. Thus, it was available for destructiveexperimental investigation within the doctoral project presented in this thesis. The bridgehad five continuous spans, was 121.5 m long and consisted of three parallel girders with a connecting slab at the top. Both the girders and slab were tested to failure to investigatetheir structural behaviour and load-carrying capacity. Non-destructive and destructivetests were also applied to determine the residual prestress forces in the bridge girders andinvestigate the in situ applicability of methods developed for this purpose. The so-calledsaw-cut method and decompression-load method were used after refinement to enabletheir application to structures of such complexity. The variation of the experimentallydetermined residual prestress forces was remarkably high, depending on the sectioninvestigated. There were also high degrees of uncertainty in estimated values, and thusare only regarded as indications of the residual prestress force.Level 1 analysis of the multi-level assessment strategy consistently underestimatedcapacity, relative to the test results, and did not provide accurate predictions of the shearrelatedfailure observed in the test. With linear FE analysis and local resistance modelsdefined by the European standard, Eurocode 2, the load-carrying capacity wasunderestimated by 32 % for the bridge girder and 55 % for the bridge deck slab. At theenhanced level of structural analysis (Level 3), nonlinear FE analyses predicted thecapacities with less than 2 % deviation from the test results and correctly predicted thefailure mode. However, for existing bridges there are many uncertainties, for instance,the FE simulations were sensitive to the level of residual prestressing, boundaryconditions and assumed material parameters. To accurately take these aspects intoaccount, bridge-specific information is crucial.The complete structural assessment procedure, combining the multi-level strategy andsafety verification framework, was evaluated in a case study. Experiences from theprevious comparative studies were used in an assessment of the Kiruna Bridge followingthe Swedish assessment code. The initial assessment at Level 1 of the multi-level strategyand safety verification, using the PSF method, indicated that the shear capacity of one ofthe girders was critical. The most adverse load case (a combination of permanent loads,prestressing and variable traffic loads) was further investigated through enhancedstructural analyses implicitly accounting for flexural and shear-related failures (Level 3).Nonlinear FE analysis and safety evaluation using the PSF method, several variants of theGRSF method and the full probabilistic analysis for resistance indicated that the permittedaxle load for the critical classification vehicle could be 5.6 – 6.5 times higher than thelimit obtained from the initial assessment at Level 1. However, the study also indicatedthat the model uncertainty was not fully considered in these values. The modeluncertainty was shown to have strong effects on the safety verification and (thus)permissible axle loads. The case study also highlighted the need for a strategy forsuccessively improving structural analysis to improve understanding of bridges’ structuralbehaviour. The refined analysis indicated a complex failure mode, with yielding of thestirrups in the bridge girders and transverse flexural reinforcement in the bridge deck slab,but with a final shear failure of the slab. It would be impossible to capture suchcomplexity in a traditional standardised assessment, which (as mentioned) indicated thatthe shear capacity of the girder limited permissible axle loads. However, nonlinear FEanalyses are computationally demanding, and numerous modelling choices are required.Besides a strategy for rationally improving the analysis and helping analysts to focus oncritical aspects, detailed guidelines for nonlinear FE analysis should be applied to reduce the analyst-dependent variability of results and (thus) the model uncertainty. Clearly, toensure the validity of bridge assessment methods under in situ conditions, theirevaluations should include in situ tests. This thesis presents outcomes of such tests, therebyhighlighting important aspects for future improvements in the assessment of existingbridges.

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Labò, Simone. "Holistic sustainable renovation of Post-World War II reinforced concrete building under a life cycle perspective by means diagrid exoskeletons." Doctoral thesis, Università degli studi di Bergamo, 2019. http://hdl.handle.net/10446/128920.

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Enormous resources are being invested in Europe to foster environmental, economic, and social sustainability; however, such relevant effort to reach ambitious targets may be a missed chance, unless a deep and systematic intervention on the built environment is undertaken targeting sustainability, safety and resilience at the same time. This thesis provide a contribution to the scientific debate, focusing on holistic renovation from outside of reinforced concrete building by embracing a life cycle perspective. Effectiveness of such an approach to the renovation with respect to traditional retrofit actions emerges both in the construction time when addressign the barriers to the renovation such as the inhabitant relocation and the existing buildgin disruption, and when broadening the time frame of the analyses, shifting from the construction time to a life cycle perspective. In this second case, the potential of the holistic approach becomes clear in reducing costs, impacts on the inhabitants and impacts on the environment over the building life cycle. The reults of this new approach is a retrofit solution based on a Life Cycle Thinking, which not only entails the use of recyclable/reusable materials, but also encourages interventions carried out from the outside the buildings, and imply the adoption of reparable, easy maintainable, adaptable and fully demountable solutions with pre-fabricated components, thus guaranteeing, at the end-of-life, the selective dismantling and reuse or recycle of the components to reduce construction waste. The described solutions, which couples structural retrofit in the renovation action, stem as an enhancement of past pioneering “camouflage” interventions, such as double-skin solutions entailing in many benefits such as the protection of human lives, resilience and the lengthening of the existing buildings service life, the repairing costs and building downtime reduction, reduction of the environmental impact associated with seismic risk over the building life cycle and long-term protection of the investment (Marini et al. 2018). Within such a new perspective, new technology options are needed to innovatively combine structural retrofit, architectural restyling and energy efficiency measures; in this work an effective retrofit solution is proposed. Among the possible retrofit solutions the diagrid structures as innovative strenghening technique from outside are investigated. In the first part of this thesis, the state of the art of diagrid design is reported. New criteria for the design of retrofit solution are set, and a design procedure for elastic diagrid is proposed. In the third chapter, a parametric evaluation of the retrofitted system through a simplified 2 DOF system is conducted, and a set of design spectra are defined in order to simplify the design procedure and derive the optimal retrofit parameter for RC buildings. Finally, a reference case study representative of the typical RC building is developed in the fifth chapter of this work to asses and validate the procedure.

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32

MANCINELLI, OSCAR. "Safety and sustainability of school buildings." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2972448.

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33

Kirschbaum, Adam. "Hodnocení konstrukcí průmyslových objektů podle ČSN ISO 13822." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240048.

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This diploma thesis deals with the evaluation of the constructions of the industrial buildings according to the ČSN ISO 13822 Standard. In the first, theoretical part, the procedures of research and evaluation of existing reinforced concrete constructions based on the ČSN ISO 13822 and ČSN 73 0038 Standards are described. Further, the theoretical part is focused on the diagnostic methods used during the evaluation of these constructions. The practical part focuses on the evaluation of the three industrial reinforced concrete buildings. It includes information about the building, the description of defects, diagnostics and the appraisal of measuring. The last part deals with a static calculation of selected parts of the supporting construction.

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Holbová, Monika. "Diagnostika železobetonové konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265583.

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This diploma thesis deals with the building survey and diagnosis of the station building of a railway station in Vítkovice. It describes process of survey and evaluation of existing reinforced concrete structures and used diagnostic methods. The survey of the object is described in the practical part of the thesis, which involves location of testing spots, taking the samples for testing from the structure, laboratory testing and evaluation of the results – determination of compressive strength of concrete with classification of concrete and elastic modulus. The last part includes static calculation of selected part of the structure.

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Cassese, Paolino. "Seismic performance of existing hollow reinforced concrete bridge columns." Tesi di dottorato, 2017. http://www.fedoa.unina.it/11503/1/Cassese_Paolino_29.pdf.

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Highway bridges can be considered as crucial civil structures for economic and social progress of urban areas. The damages to highway bridges due to earthquake events may have dramatic impact on the interested area, with or without life threatening consequences, since bridges are essential for relief operations. For these reasons, the assessment of seismic performance of existing bridge structures is a paramount issue, especially in those countries, such as Italy, where most of existing bridges was constructed before the advancement in earthquake engineering principles and seismic design codes. Several major earthquakes occurred throughout the world highlighted the seismic vulnerability of the bridge piers, due to obsolete design. If, for ordinary shaped reinforced concrete (RC) bridge columns the seismic assessment issue can be considered as almost solved, due to several analytical assessment formulations available in literature, and adopted by codes, the same cannot be said for columns with hollow-core cross section, despite their widespread use. None of the current codes addresses specialized attention to RC hollow core members, and only quite recently, attention has been paid to experimental cyclic response of hollow columns. Some critical issues for hollow RC columns are related to the assessment of their shear capacity, special focusing on degradation mechanisms, and the high shear deformation characterizing the seismic response of such elements. In the above outlined contest, a contribution in the seismic assessment of hollow bridges piers is provided by the present work: the investigation of cyclic lateral response of RC existing bridge piers with hollow rectangular and hollow circular cross-section is performed. Special attention has been focused on failure mode prediction and shear capacity assessment. A critical review of the state-of-the-art and of the theoretical background is firstly carried out: the review process has been focused on the past experimental and analytical research on seismic performance of hollow reinforced concrete bridge piers, both for hollow rectangular and hollow circular cross sections. The experimental campaign, conducted at Laboratory of the Department of Structures for Engineering and Architecture, University of Naples “Federico II”, is presented. The experimental program comprised tests on six reduced-scale RC bridge piers with hollow cross-section (four rectangular shaped and two circular shaped). The specimens were ad hoc designed in order to be representative of the existing bridge columns typical of the Italian transport infrastructures realized before 1980, by using a scaling factor equal to 1:4. The construction procedure is detailed, too. All the tests were performed in quasi-static way by applying increasing horizontal displacement cycles with constant axial load (equal to 5% of the axial compressive capacity) until collapse. The monitoring system is accurately explained: it was composed of two sub-systems, one used for global measures (forces and displacement), and the other to deeply investigate about local deformation. Experimental results for both hollow rectangular and hollow circular specimens are reported: for each specimen the results in terms of lateral load versus drift are shown and the evolution of observed damage with increasing displacement is described and related to the lateral load-drift response. An experimental analysis of deformability contributions to the top displacement is performed, mainly in order to better understand the relevance of taking into account shear deformations for bridge piers assessment. The energy dissipation capacity is also analyzed, evaluating the equivalent damping ratio and its evolution with ductility. For hollow rectangular specimens, the global response is modelled through a three-component numerical model, in which flexure, shear and bar slip are considered separately. The main goal of the numerical analysis is to reproduce the experimental deformability contributions. The last part of the work focuses on the definition of proper shear strength models for both hollow rectangular and hollow circular cross sections, and the definition of a deformability capacity model for hollow rectangular cross section. To this aim, two different experimental databases are collected and critically analyzed. The effectiveness in shear capacity and failure mode prediction of main existing shear capacity models is investigated, by applying these models to the database columns. Based on the obtained results, some modifications to existing shear strength models are discussed and proposed in order to improve their reliability for hollow columns. Finally, a new drift capacity model is developed and proposed to assess drift at shear failure of hollow rectangular columns.

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Chang, Han-Tung, and 張翰東. "Durability and Service Life Prediction of Existing Reinforced Concrete Bridges." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/45143460529925178186.

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碩士
國立臺灣海洋大學
河海工程學系
96
Both the durability problem and service life prediction of reinforced concrete(RC) structures are very important in civil engineering all over the world. The corrosion of RC structures due to chloride ion penetration into concrete is occurred damage in long-term and load-bearing-capacity is not strengthened enough. The main propose of this article is to analyze rust-expansion-cracking life-time and load-bearing-capacity life-time after the corrosion of steel in concrete. The service life of RC structures can be divided into three stages, carbonation or initiation period , depassivation period and corrosion or propagation period . The theoretical models of rust-expansion-cracking and load-bearing-capacity are used to predict the service-life of RC structures by using probability and reliability index. To verify the serviceability of theoretical models, the data of field test of the Shi-yuan viaduct, Wann-fwu bridge, Chorng-ching viaduct were used as illustrative examples. When the reliability index is 1.0, their rust-expansion-cracking life-time and load-bearing-capacity life-time are 58, 33, and 57 years and 78, 147, and 116 years, respectively. The results of this study may be applied to predicting the service life, repair, strengthening, and demolition of RC bridges or structures.

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YANG, SHANG-HENG, and 楊尚衡. "Experimental study on strengthening existing reinforced concrete short columns of buildings." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/77062320528490667724.

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MORBIN, RICCARDO. "Strategies for seismic assessment of common existing reinforced concrete bridges typologies." Doctoral thesis, 2013. http://hdl.handle.net/11577/2748884.

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Questo studio riguarda una nuova procedura probabilistica per valutare ponti esistenti stradali/ferroviari dopo un evento sismico per mezzo di curve di fragilità analitiche e ispezioni sulla struttura. In particolare, la valutazione riguarda ponti esistenti in calcestruzzo armato aventi uno schema strutturale comune in Italia (ponti multicampata in semplice appoggio). La procedura è composta di 6 fasi e ciascuna fase è stata approfondita. Le fasi 1 e 2 sono una sorta di lavoro preliminare da eseguire prima che l’evento sismico accada: l’impostazione di un database per raccogliere tutte le informazioni riguardo i ponti di una specifica rete stradale/ferroviaria (fase 1) e la costruzione delle curve di fragilità per ciascun ponte (fase 2): le curve di fragilità sono grafici che esprimono la probabilità condizionata di un manufatto di eguagliare o eccedere un certo livello di danno per diverse intensità dell’azione sismica. Poiché la fase 2 è una fase importante per i risultati finali dell’intera procedura probabilistica, è presentato un ampio studio sulla costruzione delle curve di fragilità, considerando alcuni ponti localizzati in posizioni strategiche della rete stradale della regione Veneto (Italia nord orientale) e differenti modellazioni numeriche, al fine di valutare la modellazione più conveniente per la stima della vulnerabilità sismica. Inoltre, particolare attenzione è posta sugli interventi di adeguamento con materiali FRP e il loro effetto sulla riduzione della vulnerabilità sismica del manufatto. Le altre fasi riguardano le attività da svolgere dopo un evento simico, utili per le fasi di emergenza e post- emergenza. La fase 3 riguarda un metodo per decidere se iniziare o meno le ispezioni su un ponte in relazione all’intensità sismica del terremoto accaduto; se l’intensità sismica raggiunge o supera una certa soglia, la fase 4 indica come effettuare le ispezioni visive sui manufatti, a livello probabilistico, e come generare le curve di fragilità dei ponti eventualmente danneggiati. Infine, le ultime due fasi cercano di fornire informazioni utili agli enti che gestiscono la rete stradale per ottenere un’organizzazione ottimale della rete stradale/ferroviaria nelle fasi dopo il terremoto. La fase 5 riguarda una veloce procedura per decidere se permettere o meno il traffico sui ponti che hanno subito l’evento sismico, mentre la fase 6 fornisce informazioni riguardo possibili vantaggi economici, che derivano da un confronto tra costi di ricostruzione e costi di riparazione (considerando interventi con materiali FRP) dei ponti danneggiati. Per chiarire la procedura qui descritta, si è svolto un esempio esplicativo per ogni fase.

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Su, Mor-Yuarn, and 蘇模原. "Enhancement of Shear Strength and Flexural Ductility of Existing Reinforced Concrete Beams." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/80999231734568710516.

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碩士
國立臺灣科技大學
營建工程系
87
In this study, two U-shaped steel plate systems were used to enhance the shear strength and flexural ductility of existing reinforced concrete beams. A total number of 12 full-scale cantilever beams were tested under cyclic loading to study the effectiveness of the U-shaped steel plate systems. It is found that: (1) S1 U-shaped steel plate system was able to increase the shear strength and flexural ductility of the existing beams; (2) S2 U-shaped steel plate system was also able to enhance the shear strength and flexural ductility of the existing beams, but was not as effective as S1; (3) thicker steel plate was more effective. A brief method for evaluation of shear strength and flexural ductility of existing beads was proposed, and a design guide-line for U-shaped steel plate system was also suggested.

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Liao, YenSheng, and 廖晏聖. "Carbonation Damage Evaluation and Service Life Prediction of Existing Reinforced Concrete Bridges." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/74982955694547388879.

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碩士
國立海洋大學
河海工程學系
87
The first purpose of this paper is to study the durability evaluation of concrete bridges due to carbonation damage. The method of linearly unbiased estimation associated with the JC method developed by the Joint Committee on Structural Safety is adopted to predict the mean value and standard deviation of normal distribution for the carbonation depths of concrete bridges. The reliability index and failure probability of concrete bridges are also evaluated. Since the method of linearly unbiased estimation is very suitable for the small specimen obtained from practical engineering problem, the unknown parameters can be conveniently and actually determined. In order to verify this proposed theory, ten concrete bridges in the Taipei city are individually used to predict the mean value, standard deviation, reliability index and failure probability. In this paper, the results of present investigation indicate that both the Beei-men viaduct(Reliability index =0.23) and the Jzyh-chyang bridge(Reliability index =0.39) are necessary to do a larger repair. Both the Ay-gwo west road viaduct(Reliability index =0.92) and the Shi-yuan bridge(Reliability index =0.88) are just needed to do a small repair. The other bridges(Reliability index =1~2.0) can be safely serviceable. The carbonation depth of concrete is an important index for evaluating the damage and durability of reinforced concrete structures. In this paper, the second purpose focuses on the study of carbonation problems of concrete structures at existing cracks. The carbonation process of concrete structures at cracks consists of four steps: diffusion of into the crack, diffusion of into the concrete, chemical reaction, and diffusion of hydroxylions. The present study indicates that, as regards the pure process of carbonation, the same basic interrelations given for uncracked concrete are valid for carbonation in the crack regions as well. Carbonation can penetrate into the interior of cracked concrete much faster than it does through uncracked concrete. Under the static loading of the existing reinforced concrete structures with cracks, the carbonation depth at constant crack width can be predicted by using statistical methods.

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Pan, Kuan-Yu, and 潘冠宇. "Seismic Retrofit of Existing Reinforced Concrete Frames Using Buckling-Restrained Braced Frames." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/67435522159198035390.

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碩士
國立臺灣大學
土木工程學研究所
102
With the advancement in earthquake engineering technology and seismic provisions, many existing old reinforced concrete (RC) structures do not meet the current seismic standards. Seismic retrofit using steel braced frames has been found as a popular method to improve the seismic performance of RC buildings. For this purpose, closely-spaced post-installed anchors are widely adopted in the interface between the RC and steel frames to transfer the seismic loads. It often requires a substantial amount of on-site work of hole drilling and installation of anchors on the RC members. In this research, three identical strong-beam-weak-column RC frames are retrofitted, each with or without a diagonal buckling-restrained brace (BRB) incorporated into a steel braced frame using WT sections on four sides. Instead of applying the post-installed anchors to transfer the seismic loads, high-strength mortar bearing blocks at the four corners of the RC frame are constructed. The loads in the steel frame are transferred to the RC frame through the bearing blocks. This approach can reduce the usage of large amount of post-installed anchors. The purpose of this research is to evaluate the performance of the retrofitted frame, and investigate the load transfer mechanism between the RC frame and the steel frame. In this study, cyclic loading tests were applied on two RC frames retrofitted with steel braced frames using BRBs (BRB-S-WTF and BRB-D-WTF), and on one RC frame retrofitted with the steel frame without the brace. Test results show that, the lateral strength of BRB-D-WTF continued to increase until reaching 3% drift ratio, and developed 1060kN story shear (3 times of the bare RC frame) before the BRB core fractured at the 5% drift ratio. When the brace is in compression, it imposes a compressive force near the tip of the frame corner. This compressive force may cause an RC joint failure or a corbel-type failure in the RC column. In this research, these two failure modes are evaluated using the softened strut-and-tie model. The strength of the compressive strut in the beam-to-column joint is 810kN. In the BRB-S-WTF specimen, the estimated maximum brace compressive force is 1025kN. Thus, the beam-to-column joint failure was predicted. In the BRB-D-WTF specimen, the estimated maximum brace compressive force is 807kN. Thus, no beam-to-column joint failure was anticipated. The predictions match the test results. The concrete compressive strength of the RC column is 25MPa. In the BRB-S-WTF specimen, the strength demand on the corbel computed using the softened strut-and-tie model is 25.1MPa and approximately equals 25MPa. Thus, it predicted that the corbel failure might occur. In the BRB-D-WTF specimen, the strength demand on the corbel is 19.5MPa and less than 25MPa. The model predicted that the corbel failure should not occur. These two predictions also match the test results. Therefore, it appears that the softened strut-and-tie model is effective in predicting the joint failure and corbel failure of the RC frame. In this research, a simplified method for estimating the lateral strength of the retrofitted structure and the internal forces of RC beams and columns is developed from observing the load transfer mechanism found in the Abaqus finite element model (FEM) analysis results. The estimated lateral strengths for the BRB-S-WTF and BRB-D-WTF specimens are 1120kN and 973kN, predicted the experimental results of 1289kN and 1018kN, respectively. This confirms that the proposed simplified method is effective for estimation of the lateral strength of the retrofitted frame, and computing the estimated internal force demands on RC frame members. This study proposes a design procedure for retrofitting existing RC frames with buckling-restrained braced frames.

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郭峻輔. "Studies of the Carbonation Service Life Prediction of Existing Reinforced Concrete Bridges." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/66709055285242002690.

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碩士
國立臺灣海洋大學
河海工程學系
97
The carbonation problem due to the carbon dioxide in atmosphere penetrated into concrete through pore void is one of important factors of corrosion of existing reinforced concrete (RC) structures. Aside from material factor, both temperature and relative humidity (RH) are the principal environment factors which influence the carbonation problem of existing RC structures. When RH are larger or less than 70%, the carbonation zone in concrete can be divided into carbonated and noncarbonated zones or carbonated, partially carbonated and noncarbonated zones, respectively. The main aim of this article is to predict the carbonation life of existing RC bridges. The investigated methods are used to find the analytical solutions of one-dimensional linear (diffusivity D = constant) and nonlinear (D ≠ constant) diffusion and diffusion-chemical reaction equations associated with initial and boundary conditions, respectively. The carbonation life can be calculated from the analytical solutions through the Mathematica software. These theoretical models are applied to predicting the carbonation life of existing Dah-du and Dah-jin RC bridges in Taiwan. The results of present studies show that the one-dimensional nonlinear diffusion equation is suitable for bridges under RH＞70% condition whereas the one-dimensional linear diffusion-chemical reaction equation is suitable for bridges under RH≦70%. The studied results may be offered as a crucial reference for engineering decision making for repair, strengthening or demolition of existing RC bridges.

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YEN, WEI-LI, and 顏瑋利. "Research on Seismic Retrofitting for Existing Buildings with Exterior Reinforced Concrete Frames." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/m7ag8d.

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碩士
國立臺北科技大學
土木工程系土木與防災碩士班
106
This research is for existing reinforced concrete structures and uses the external reinforced concrete frames method to retrofit. Study on traditional reinforced concrete retrofit methods (Column-Jacketing, shear walls and etc.). Those that traditional methods usually affect existing building. Take some cases for example-internal structures interior spaces are changed, people can’t stay in buildings, and existing walls, windows and doors may need to reinstalled. Those reasons mentioned above restrict promotion of retrofits on buildings. The research on RC existing structures with RC external retrofit frames is taken at NCREE. The research includes experiments and structural analysis. Three specimen are tested with reversed cyclic loading to compare the behaviors between an existing and and two retrofitted frames. The results show that external retrofit frames are effective to increase the lateral strength. Anchors of the interfaces between and there is no separation between existing and external frames. The analytical to model research is based on the experimented test results with ETABS external retrofit frames on experimental specimen and retrofit examples. The results show that the analytical results are more conservative than the experimental results on the external frames and external retrofit frames are also effective to increase the PGA of the retrofit examples.

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Orton, Sarah Lynn 1978. "Development of a CFRP system to provide continuity in existing reinforced concrete buildings vulnerable to progressive collapse." Thesis, 2007. http://hdl.handle.net/2152/3241.

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Reinforced concrete buildings may be vulnerable to progressive collapse due to a lack of continuous reinforcement. Progressive collapse is an extreme form of collapse that is disproportionate to the originating cause. Such collapses cause not only significant damage to buildings, but also greater loss of life and injuries. Carbon fiber reinforced polymer (CFRP) may be used to retrofit existing reinforced concrete beams and provide the missing continuity needed to resist progressive collapse. This research focuses on retrofitting the beams in a reinforced concrete building to provide sufficient continuity to reach catenary action. The catenary action may allow the beam to carry vertical loads at large displacements if a supporting column were removed. The CFRP can provide continuity through the negative moment reinforcement or through the positive moment reinforcement. The research was broken into three major components. Anchorage tests form the design basis of the CFRP retrofit and ensure that the capacity of the retrofit can be accurately predicted. Continuity tests determine if the CFRP retrofit is capable of providing continuity and if the retrofit will allow the beam to reach catenary action and sustain a load representing resistance to progressive collapse. The analysis model forms a set of equations for catenary action so the results can be applied to reinforced concrete beams in general. Forty anchorage tests, eight continuity tests, and one analysis model were constructed and evaluated. The anchorage tests found that carbon fiber anchors enabled improved utilization of the tensile capacity of a CFRP sheet and improved the efficiency of material usage in CFRP retrofits. The continuity tests found that beams without continuous reinforcement can reach catenary action (depending on design details) and a CFRP retrofit, if designed correctly (placed in locations that do not cause rebar fracture before catenary), may be able to reduce vulnerability to progressive collapse. The analysis model was able to accurately predict the load-deflection behavior of a reinforced concrete beam in catenary action. The overall conclusion is that a CFRP retrofit can reduce vulnerability to progressive collapse in reinforced concrete buildings.
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(9873083), Robert Richard Jacobs. "Experimental Evaluation of Flexural Strengthening Methods for Existing Reinforced Concrete Members Using Fiber Reinforced Polymer (FRP) Systems." Thesis, 2020.

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Research has shown that many adjacent box beam bridges in Indiana experience premature deterioration. Primarily caused by leaking joints between beams, this deterioration leads to corrosion and/or fracturing of prestressing strands, ultimately resulting in flexural deficiency of the bridge. A testing program was designed to simulate this observed deterioration by constructing test specimens and implementing various strengthening techniques using fiber reinforced polymer (FRP) systems. The objective of this testing program is to investigate the effectiveness of FRP strengthening systems to increase or even regain the full capacity of beams that have effectively lost tension reinforcing steel due to corrosion. The FRP-strengthened beam specimens incorporate the use of near-surface-mounted and externally bonded systems. Reinforcing bars in the beams are excluded or cut to simulate deterioration. Furthermore, two different methods of end anchorage for the externally bonded sheets, FRP fan anchorage and U-wrap anchorage, are investigated. Results and conclusions from the testing program are described in order to help advise best practices in implementing the aforementioned strengthening systems.

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Huang, De-Zhi, and 黃德治. "Analysis and simulation of push over test for an existing Reinforced Concrete Building." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/90288428673223946892.

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碩士
中原大學
土木工程研究所
95
Analysis of the seismic assessment for the building result that relates to plastic hinge property for every member. But the plastic hinge property with studied the theory in the past, no studies have compared to existing building test data. So since the 94th year of the Republic of China, the National Center for Research on Earthguake Engineering carry out a series of static push over tests for existing building, in order to get result of the correspond to earthquake damage of reality. 　　This text use of various kinds of theories, calculate the intensity and plastic hinge property of the beam, colum and brick wall. And used to analysis of nolinear static push over in SAP2000 to simulation of the behavior and way of destroying in earthquake of the building. Then compare with results of the push over test for existing building in order to look for a good simulation method.

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Chu, Ting-Pang, and 朱定邦. "Applications of Fuzzy Theory to Determine Repair Rankings for Existing Reinforced Concrete Bridges." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/13809522840268264151.

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碩士
國立臺灣海洋大學
河海工程學系
92
Abstract In this article, the principal propose was applying the concept of fuzzy mathematics to determining the repair ranking for existing reinforced concrete (RC) bridges. Firstly, both the comparison matrix method and the D.(degree) E.(extent) R.(relevancy) evaluation method were provided for finding the weighting value and ranking of damage evaluation for ten existing RC bridges in Keelung, Taiwan. The evaluated repair ranking result obtained from the proposed method is: Fuh-min, Guan-in, Wuu-der, Jong-san, Jong-jeng, Shang-ren, Long-men, Jong-her bridges. Secondly, we proposed the multi-pole fuzzy pattern recognition evaluation method to find the optimal relative membership grade of an evaluated bridge attributed to any grade. Five existing RC bridges in Taiwan are adopted as an illustrative example. The repair ranking is the Tou-chyan-shi, Dah-jin, Lin-bian, Jong-jang and Shuang-yuan bridges. The predicted result is compared with the result obtained by the D.E.R. evaluation method. Finally, we proposed the fuzzy synthetic evaluation method, which is used the analytic hierarchy process for determining a factor weight vector, to assess the repair ranking of existing RC bridges. The predicted result is compared with the result obtained by the wide bound method. The predicated results obtained from both the proposed and wide bound methods had the same repair ranking. The present study results indicate that the proposed methods based on the fuzzy mathematics are reasonable, feasible and reliable. The results presented in this research work can be used as a crucial reference of engineering decision making for repair, strengthening or demolition for existing RC bridges.

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Dumaru, Rakesh. "Seismic Performance Assessment and Strengthening Techniques for Existing Reinforced Concrete Buildings in Nepal." Doctoral thesis, 2018. https://repositorio-aberto.up.pt/handle/10216/116401.

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Dumaru, Rakesh. "Seismic Performance Assessment and Strengthening Techniques for Existing Reinforced Concrete Buildings in Nepal." Tese, 2018. https://repositorio-aberto.up.pt/handle/10216/116401.

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Kim, InSung. "Use of CFRP to provide continuity in existing reinforced concrete members subjected to extreme loads." 2008. http://hdl.handle.net/2152/17915.

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A special problem in many reinforced concrete structures built in the 1970s and earlier is the lack of continuity between elements. Continuity is a characteristic of structures essential to preventing collapse. Therefore, in extreme loading conditions such as loss of a column support due to terrorist attack or if earthquake or other extreme actions occur, the structures could be vulnerable to collapse. The study reported here focused on two structural discontinuities in existing reinforced concrete structures, discontinuity in bottom reinforcement in beams (horizontal discontinuity) and poorly detailed lap splices in columns (vertical discontinuity). The objective of this study was to develop rehabilitation methods using CFRP to provide continuity of reinforcement in existing structures. To develop the rehabilitation methods, two separate experimental studies were conducted using beam and column specimens. CFRP materials were applied to the bottom or side face of a beam and anchored using CFRP anchors or U-wraps to provide horizontal continuity in bottom reinforcement and tested under dynamic loading. After CFRP rehabilitation, the ductility of the bottom reinforcement and large rotational capacity of the beam were realized. CFRP materials were also applied to the lap splice region in square and rectangular columns which exhibited a brittle splice failure as-built. After rehabilitating the columns using CFRP jackets and anchors, the failure mode changed from a brittle splice failure to yield of column reinforcement, and the strength and deformation capacity were improved under both monotonic and cyclic loading. Based on the results of beam and column tests, design guidelines for CFRP rehabilitation were proposed. Horizontal and vertical continuities can be provided through the use of CFRP for rehabilitating existing reinforced concrete structures that were designed prior to the introduction of codes that require continuous reinforcement along members and between adjacent members. The vulnerability of such structures to collapse can be reduced through rehabilitation.
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