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1
Praticò, Lucia. "Analisi di vulnerabilità sismica di strutture prefabbricate mediante curve di fragilità." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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Sviluppo di una metodologia speditiva per la valutazione della vulnerabilità sismica di aree industriali caratterizzate da capannoni prefabbricati in CA monopiano.
Individuazione dei parametri di classificazione delle strutture, per determinare le categorie principali di telai. Analisi IDA su modelli di telai per poi ricavare le curve di fragilità per ciascuna categoria.
Combinazione delle curve di vulnerabilità a livello di singola struttura, e quindi calcolo del numero di collassi per un'intera area industriale. Applicazione all'area di San Felice sul Panaro.
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Tahir, Haseeb. "Development of Fragility Curve Database for Multi-Hazard Performance Based Design." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/71794.
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There is a need to develop efficient multi-hazard performance based design (PBD) tools to analyze and optimize buildings at a preliminary stage of design. The first step was to develop a database and it is supported by five major contributions: 1) development of nomenclature of variables in PBD; 2) creation of mathematical model to fit data; 3) collection of data; 4) identification of gaps and methods for filling data in PBD; 5) screening of soil, foundation, structure, and envelope (SFSE) combinations.. A unified nomenclature was developed with the collaboration of a multi-disciplinary team to navigate through the PBD. A mathematical model for incremental dynamic analysis was developed to fit the existing data in the database in a manageable way. Three sets of data were collected to initialize the database: 1) responses of structures subjected to hazard; 2) fragility curves; 3) consequence functions. Fragility curves were critically analyzed to determine the source and the process of development of the curves, but structural analysis results and consequence functions were not critically analyzed due to lack of similarities between the data and background information respectively. Gaps in the data and the methods to fill them were identified to lay out the path for the completion of the database. A list of SFSE systems applicable to typical midrise office buildings was developed. Since the database did not have enough data to conduct PBD calculations, engineering judgement was used to screen SFSE combinations to identify the potential combinations for detailed analysis. Through these five contributions this thesis lays the foundation for the development of a database for multi- hazard PBD and identifies potential future work in this area.Master of Science
3
Patrignani, Elia. "Analisi sismica e determinazione di curve di fragilità per strutture in muratura." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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Il patrimonio edilizio italiano è in gran parte costituito da edifici in muratura di diverse età costruttive. La maggior parte di essi si concentra nei primi anni del 1900 per poi subire una progressiva diminuzione fino ad arrivare agli anni 2000. L’evoluzione delle normative volta a fornire uno strumento per la progettazione antisismica, così come le tecnologie e i materiali utilizzati inizialmente, erano ovviamente sprovvisti dei progressi acquisiti negli ultimi anni e questo rende gli edifici datati più vulnerabili nei confronti di un qualsiasi evento sismico. Diventa dunque importante conoscere e saper individuare quelli che sono i fattori che più incidono nel conteggio totale dei danni dovuti a un terremoto, sia a livello economico che sociale, specialmente negli ultimi anni in cui l’attività sismica è diventata più frequente.
Lo scopo di questa tesi è quello di individuare e analizzare le caratteristiche costruttive che più influenzano il comportamento di una struttura. Le analisi sono basate su una documentazione reale dei danni subiti dagli edifici durante il terremoto dell’Emilia del 2012. Attraverso indagini statistiche su tali dati si studiano le diverse parti di un edificio e si costruiscono relazioni tra le scelte costruttive e il livello di danno riportato dalla struttura e dai suoi singoli elementi.
Quindi, una volta individuate le tipologie più a rischio, vengono scelti due edifici esistenti che rispecchiano tali caratteristiche. Su di essi viene eseguita una modellazione a macroelementi, rispettando geometria e valori dei parametri meccanici della muratura. Le analisi prevedono la creazione delle curve forza-spostamento, il confronto tra spostamento ultimo e spostamento richiesto, fino ad arrivare alla costruzione delle curve di fragilità, mettendo in relazione i parametri meccanici della muratura e diversi parametri che rappresentano l’intensità dell’evento sismico.
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Gil, Edward Matthew. "Computational Modeling of Glass Curtain Wall Systems to Support Fragility Curve Development." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/94051.
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With the increased push towards performance-based engineering (PBE) design, there is a need to understand and design more resilient building envelopes when subjected to natural hazards. Since architectural glass curtain walls (CW) have become a popular façade type, it is important to understand how these CW systems behave under extreme loading, including the relationship between damage states and loading conditions. This study subjects 3D computational models of glass CW systems to in- and out-of-plane loading simulations, which can represent the effects of earthquake or hurricane events. The analytical results obtained were used to support fragility curve development which could aid in multi-hazard PBE design of CWs.
A 3D finite element (FE) model of a single panel CW unit was generated including explicit modeling of the CW components and component interactions such as aluminum-to-rubber constraints, rubber-to-glass and glass-to-frame contact interactions, and semi-rigid transom-mullion connections. In lieu of modeling the screws, an equivalent clamping load was applied with magnitude based on small-scale experimental test results corresponding to the required screw torque. This FE modeling approach was validated against both an in-plane racking displacement test and out-of-plane wind pressure test from the literature to show the model could capture in-plane and out-of-plane behavior effectively.
Different configurations of a one story, multi-panel CW model were generated and subjected to in- and out-of-plane simulations to understand CW behavior at a scale that is hard to test experimentally. The structural damage states the FE model could analyze included: 1) initial glass-to-frame contact; 2) glass/frame breach; 3) initial glass cracking; 4) steel anchor yielding; and 5) aluminum mullion yielding. These were linked to other non-structural damage states related to the CW's moisture, air, and thermal performance. Analytical results were converted into demand parameters corresponding to damage states using an established derivation method within the FEMA P-58 seismic fragility guidelines. Fragility curves were then generated and compared to the single panel fragility curves derived experimentally within the FEMA P-58 study. The fragility curves within the seismic guidelines were determined to be more conservative since they are based on single panel CWs. These fragility curves do not consider: the effects of multiple glass panels with varying aspect ratios; the possible component interactions/responses that may affect the extent of damages; and the continuity of the CW framing members across multiple panels.
Finally, a fragility dispersion study was completed to observe the effects of implementing the Derivation method or the Actual Demand Data method prescribed by FEMA P-58, which differ on how they account for different levels of uncertainty and dispersion in the fragility curves based on analytical results. It was concluded that an alternative fragility parameter derivation method should be implemented for fragility curves based on analytical models, since this may affect how conservative the analytically based fragility curves become at a certain probability of failure level.Master of Science
Performance-based engineering (PBE) can allow engineers and building owners to design a building envelope for specific performance objectives and strength/serviceability levels, in addition to the minimum design loads expected. These envelope systems benefit from PBE as it improves their resiliency and performance during natural multi-hazard events (i.e. earthquakes and hurricanes). A useful PBE tool engineers may utilize to estimate the damages an envelope system may sustain during an event is the fragility curve. Fragility curves allow engineers to estimate the probability of reaching a damage state (i.e. glass cracking, or glass fallout) given a specified magnitude of an engineering demand parameter (i.e. an interstory drift ratio during an earthquake). These fragility curves are typically derived from the results of extensive experimental testing of the envelope system. However, computational simulations can also be utilized as they are a viable option in current fragility curve development frameworks. As it’s popularity amongst owners and architects was evident, the architectural glass curtain wall (CW) was the specific building envelope system studied herein. Glass CWs would benefit from implementing PBE as they are very susceptible to damages during earthquakes and hurricanes. Therefore, the goal of this computational research study was to develop fragility curves based on the analytical results obtained from the computational simulation of glass CW systems, which could aid in multi-hazard PBE design of CWs. As v opposed to utilizing limited, small experimental data sets, these simulations can help to improve the accuracy and decrease the uncertainties in the data required for fragility curve development. To complete the numerical simulations, 3D finite element (FE) models of a glass CW system were generated and validated against experimental tests. 11 multi-panel CW system configurations were then modeled to analyze their effect on the glass CW’s performance during in-plane and out-of-plane loading simulations. These parametric configurations included changes to the: equivalent clamping load, glass thickness, and glass-to-frame clearance. Fragility curves were then generated and compared to the single panel CW fragility curves derived experimentally within the FEMA P-58 Seismic Fragility Curve Development study. The fragility curves within FEMA P-58 were determined to be more conservative since they are based on single panel CWs. These fragility curves do not consider: the effects of multiple glass panels with varying aspect ratios; the possible component interactions/responses that may affect the extent of damages; and the continuity of the CW framing members across multiple panels. Finally, a fragility dispersion study was completed to observe the effects of implementing different levels of uncertainty and dispersion in the fragility curves based on analytical results.
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Franceschini, Iolanda. "Analisi di fragilità di strutture ricettive della zona costiera dell'Emilia-Romagna." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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Il presente lavoro si è concentrato sulle strutture ricettive presenti sulla riviera romagnola, con lo scopo di individuare ed analizzare le caratteristiche costruttive che maggiormente influenzano il comportamento sotto sisma. Attraverso indagini statistiche dei dati ISTAT si è cercato individuare una classe di strutture ricettive tipologiche caratteristiche del territorio analizzato, in termini di tipologia costruttiva, epoca di costruzione e numero di piani fuori terra.
La struttura ricettiva analizzata è una struttura mista, situata nel Comune di Bellaria – Igea Marina. Di tale struttura è stata eseguita una modellazione a macroelementi con il software 3MURI, rispettando la geometria e i valori dei parametri meccanici degli elementi che la compongono, realizzando diversi modelli con diverse variazioni, sia riguardanti i valori dei parametri meccanici del calcestruzzo armato che quelli della muratura.
Sono state eseguite le analisi pushover, dalle quali sono state ottenute le curve di capacità in termini di forza – spostamento, successivamente è stato eseguito il confronto tra lo spostamento ultimo e lo spostamento richiesto, valutato con un metodo modificato (metodo di Guerrini), fino ad arrivare alla costruzione delle curve di fragilità che, in funzione dei diversi livelli di scuotimento del terreno, definiti secondo l’accelerazione massima al suolo (PGA), consentono di valutare la probabilità di superamento di fissati livelli di danno.
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Nielson, Bryant G. "Analytical Fragility Curves for Highway Bridges in Moderate Seismic Zones." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7542.
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Historical seismic events such as the San Fernando earthquake of 1971 and the Loma Prieta earthquake of 1989 did much to highlight the vulnerabilities in many existing highway bridges. However, it was not until 1990 that this awareness extended to the moderate seismic regions such as the Central and Southeastern United States (CSUS). This relatively long neglect of seismic issues pertaining to bridges in these moderate seismic zones has resulted in a portfolio of existing bridges with seismic deficiencies which must be assessed and addressed.
An emerging decision tool, whose use is becoming ever increasingly popular in the assessment of this seismic risk, is that of seismic fragility curves. Fragility curves are conditional probability statements which give the probability of a bridge reaching or exceeding a particular damage level for an earthquake of a given intensity level. As much research has been devoted to the implementation of fragility curves in risk assessment packages, a great need has arisen for bridge fragility curves which are reliable, particularly for those in moderate seismic zones. The purpose of this study is to use analytical methods to generate fragility curves for nine bridge classes which are most common to the CSUS. This is accomplished by first considering the existing bridge inventory and assessing typical characteristics and details from which detailed 3-D analytical models are created. The bridges are subjected to a suite of synthetic ground motions which were developed explicitly for the region. Probabilistic seismic demand models (PSDM) are then generated using these analyses. From these PSD models, fragility curves are generated by considering specific levels of damage which may be of interest. The fragility curves show that the most vulnerable of all the bridge nine bridge classes considered are those utilizing steel girders. Concrete girder bridges appear to be the next most vulnerable followed by single span bridges of all types. Various sources of uncertainty are considered and tracked throughout this study, which allows for their direct implementation into existing seismic risk assessment packages.
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Saler, Elisa. "Seismic vulnerability and fragility of school buildings in Italy. A multiscale approach to assessment, prioritisation, and risk evaluation." Doctoral thesis, Università degli studi di Trento, 2022. http://hdl.handle.net/11572/348119.
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The importance of school buildings, among the built heritage of a community, is largely acknowledged. Due to past seismic events, damage or even collapse of schools have had a huge social impact. The safety of children and youth has a fundamental priority and, in addition, the unsafety of schools can aggravate social dispersion phenomena which follow an earthquake. In the aftermath of the Molise earthquake (2002), which caused the collapse of a primary school in San Giuliano di Puglia (Campobasso, Italy) and the consequent death of 27 children and a teacher, the Italian government issued a national plan for the seismic vulnerability assessment of relevant and strategic structures all over the country. The huge number of structures to be evaluated makes this operation extremely complex and, after almost twenty years, it still requires efficient and cost-effective (also in terms of execution time) tools to be effectively planned.
More recently, the United Nations adopted, in March 2015, the Sendai Framework for Disaster Risk Reduction 2015-2030, which is articulated in “priorities”, providing actions to be implemented. Specifically, Priority 1 is focused on “understanding disaster risk”, while Priority 2 sets the goal of “strengthening disaster risk governance to manage disaster risk”. Both objectives require to deepen knowledge of risks and of its components (i.e., hazard, exposure and vulnerability) at various territorial scale (e.g., national or urban).
This thesis presents the seismic vulnerability and fragility assessment of school buildings in Italy, to address this problem at multiple scales, at municipality level and at national level, also including investigations on case studies for refined modelling.
First, a prioritisation procedure to sort school buildings part of an urban stock by their seismic vulnerability is proposed. This procedure has the aim of supporting local administrations and enterprises in charge with built stocks in decision-making for the allocation of limited funds for retrofit. The knowledge process of the building stock is comprised of on-site visual surveys and retrieval of original projects documentations. Then, the priority list is defined based on the combination of a qualitative evaluation and of a quantitative capacity/demand ratio resulting from a simplified mechanics-based model. The former results from the application of a form, counting structural and non-structural deficiencies, which is proposed in this work for masonry, reinforced concrete (r.c.), and mixed masonry-r.c. buildings, by updating an existing form. The priority-ranking procedure was applied to r.c. school buildings managed by the Municipality of Padova, in north-east Italy.
Then, in the second part of the thesis, the research focuses on the fragility assessment of macro-classes of buildings, representative of the Italian school taxonomy, aimed at risk evaluation at national scale.
Based on the Italian school building census, macro-classes of buildings were identified according to a limited number of parameters (i.e., the construction material, age of construction, number of stories, and plan area). Fragility curves were derived for five damage states (from slight damage to complete collapse), with reference to the European Macroseismic Scale (EMS98).
For masonry schools, fragility curves were derived for 265 building types by means of a simplified mechanics-based approach, named Vulnus, which accounts for both in-plane and out-of-plane responses.
Fragility assessment was also carried out for a macro-class of r.c. school buildings by selecting two representative schools from the above-mentioned urban stock managed by the Municipality of Padova. A non-linear fibre model was developed for each prototype building, taking into account its specific features, such as the presence of infills and of non-seismic joints. Non-Linear Time History Analyses (NLTHA) were carried out by applying a great number of natural and scaled ground motion records, covering a large range of seismic intensities. Fragility curves were derived by statistically processing the outcomes of NLTHA.
Thus, the application of two alternative approaches for fragility estimate are provided in this work.
Finally, damage maps at national scale are provided by implementing the obtained fragilities, showing the distribution of expected damage for a selected return period and for observation time windows.
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Ay, Bekir Ozer. "Fragility Based Assessment Of Low." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607629/index.pdf.
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In this study, structural vulnerability of reinforced concrete frame structures by considering the country&ndashspecific characteristics is investigated to manage the earthquake risk and to develop strategies for disaster mitigation. Low&ndash
rise and mid&ndash
rise reinforced concrete structures, which constitute approximately 75% of the total building stock in Turkey, are focused in this fragility&ndash
based assessment. The seismic design of 3, 5, 7 and 9&ndash
story reinforced concrete frame structures are carried out according to the current earthquake codes and two dimensional analytical models are formed accordingly. The uncertainty in material variability is taken into account in the formation of structural simulations. Frame structures are categorized as poor, typical or superior according to the specific characteristics of construction practice and the observed seismic performance after major earthquakes in Turkey. The demand statistics in terms of maximum interstory drift ratio are obtained for different sets of ground motion records. The capacity is determined in terms of limit states and the corresponding fragility curves are obtained from the probability of exceeding each limit state for different levels of ground shaking. The results are promising in the sense that the inherent structural deficiencies are reflected in the final fragility functions. Consequently, this study provides a reliable fragility&ndash
based database for earthquake damage and loss estimation of reinforced concrete building stock in urban areas of Turkey.
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Giraudeau, Fabien. "Construction de courbes de fragilité sismique par la représentation de Karhunen-Loève." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22540/document.
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La probabilité de défaillance d’une structure sous séisme est représentée à l’aide de « courbes de fragilité ». Pour les estimer, nous proposons d’enrichir une base de données pré-existante à l’aide du modèle de l’article de F. Poirion et I. Zentner, Stochastic model construction of natural hazards given experimental data, qui se fonde sur la représentation de Karhunen-Loève. Les signaux générés sont triés par classes d’indicateur de nocivité sismique à l’aide d’un algorithme de partitionnement de données. Malgré la ressemblance certaine que présentent plusieurs signaux simulés, et les conséquences que nous tirons de ce problème, ils sont soumis à la structure. Les signaux de réponses résultants sont eux aussi enrichis, en prenant en compte certaines incertitudes afin de construire un intervalle autour de la courbe. La méthode fonctionne pour tout indicateur de nocivité sismique, et permet de s’affranchir de plusieurs hypothèses simplificatrices courantes. Les caractéristiques du scénario sismique sont conservées lors de l’enrichissement, et le processus modélisant le mouvement du sol garde toute sa généralité. Notre démarche est validée d’abord sur un cas simple, puis sur un cas industrielThe failure probability of a structure under earthquake is represented with « fragility curves ». To estimate them, we propose to enrich a pre-existing data basis using the model of the article Stochastic model construction of natural hazards given experimental data, written by F. Poirion et I. Zentner, which is based on the Karhunen-Loeve expansion. The generated signals are sorted by seismic indicator classes using a data partitioning algorithm. Despite the resemblance between some simulated signals, and the consequences we draw from this problem, the structure is submitted to them. The resulting response signals are also enriched, taking into account uncertainties to construct an interval around the curve. The method works for any seismic indicator, and overcomes several common simplifying assumptions. The characteristics of the seismic scenario are preserved during the enrichment, and the process modeling the ground motion retains its generality. Our approach is first validated on a simple case, then on an industrial case
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伊藤, 義人, Yoshito ITOH, 光永 和田, and Mitsunaga WADA. "イベントを考慮した交通基盤施設のライフサイクル評価手法に関する研究." 土木学会, 2003. http://hdl.handle.net/2237/8633.
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Saeidi, Ali. "La vulnérabilité des ouvrages soumis aux aléas mouvements de terrains ; développement d'un simulateur de dommages." Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL003N/document.
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L’objectif de cette thèse a été de concevoir et développer un simulateur de dommages permettant d’étudier la vulnérabilité d’un territoire soumis à des aléas de mouvements de terrains associés à la présence d’exploitations souterraines. Ce développement repose sur la combinaison d’une méthode de prévision des affaissements miniers, de fonctions de vulnérabilité pour l’évaluation des dommages et d’une base de données des bâtiments. L’enjeu scientifique est le développement de fonctions de vulnérabilité pour les bâtiments en zone d’affaissement minier. Ces fonctions sont comparables à celles utilisées vis-à-vis d’autres aléas comme les séismes et les tsunamis. On a développé et appliqué une méthodologie basée sur des simulations de type Monte-Carlo qui utilise les méthodes existantes d’évaluation des dommages dans les zones d’affaissement minier (méthodes empiriques ou analytiques). Elle permet de prendre en compte l’incertitude sur les paramètres géométriques et mécaniques du bâti. Afin de valider cette méthodologie, les dommages estimés par les fonctions vulnérabilité développées pour des bâtiments en maçonnerie du bassin ferrifère lorrain sont comparées aux dommages observés, consécutifs aux affaissements de 1996 à 1999 en Lorraine. Dans une étape suivante, la méthode des fonctions d’influence a été implémentée dans le simulateur avec certains développements permettant de tenir compte de la variabilité des angles d’influences et permettre le calcul des déformations horizontales du terrain. Les résultats de cette méthode sont validés sur un cas d’affaissement observé dans le bassin ferrifère de lorrain. Enfin, une approche probabiliste d’évaluation des dommages est implémentée pour tenir compte de différents scénarios d’affaissement possibles. L’application sur les bâtiments de la ville de Joeuf, permet d’illustrer les différents résultats obtenusThe objective of this thesis has been the design and the development of a damage simulator for evaluation of building damage in subsidence regions affected by undergrounds excavations. The simulator is combining a method for the subsidence prediction, vulnerability functions for assessment of building damage and a database of buildings. The scientific challenge is the development of vulnerability functions for buildings in subsidence regions. These functions are similar to those used for other hazards such as earthquakes and tsunamis. We then developed and applied a methodology based on Monte-Carlo simulations which involves existing methods of building damage assessment in subsidence area (empirical or analytical methods). It allows to take into account uncertainties on both geometrical and mechanical parameters of buildings. To validate this methodology, damages given by the vulnerability functions developed for masonry buildings in the Lorraine Iron ore field are compared to observed damages, resulting from subsidence from 1996 to 1999 in Lorraine. In a next step, the method of influence functions is implemented in the simulator with developments to take into account variability of the influence angles and to allow the calculation of horizontal ground strain. Results of this method are validated with a subsidence case study in the Lorraine iron ore field. Finally, a probabilistic approach to assess damage is implemented in the simulator to take into account different scenarios of possible subsidence. The application of the simulator on the buildings of the Joeuf city, allows to illustrate the different results
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Wang, Mengg. "Deep Learning-based Time-dependent Seismic Fragility Analysis of Aging Highway Bridges." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/24334.
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Highway bridges, as exposed to the threats induced by both long-term aging effects and unexpected earthquakes, are most crucial but vulnerable components in a transportation network. The traditional time-dependent seismic fragility curves generation methods for aging bridges require highly repetitive and extremely time-consuming analysis when changing the aging years of the bridges. Additionally, a transportation network generally comprises hundreds of bridges, making it impractical to generate fragility curves for individual bridge in a network using the traditional fragility curves generation methodology. These limitations have motivated the study of developing efficient and accurate seismic fragility curves generation methodology. In this study, a deep learning-based fragility curves generation methodology has been proposed. A new improved activation function named DLog is proposed to address the limitations and problems of the current deep neural networks and being used to construct the deep neural network for fragility curves generation. The Proposed framework, numerical tests and applications are concluded in this work.
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Jane, Robert. "Improving the representation of the fragility of coastal structures." Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/13080.
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Robust Flood Risk Analysis (FRA) is essential for effective flood risk management. The performance of any flood defence assets will heavily influence the estimate of an area's flood risk. It is therefore critical that the probability of a coastal flood defence asset incurring a structural failure when subjected to a particular loading i.e. its fragility is accurately quantified. The fragility representations of coastal defence assets presently adopted in UK National FRA (NaFRA) suffer three pertinent limitations. Firstly, assumptions relating to the modelling of the dependence structure of the variables that comprise the hydraulic load, including the water level, wave height and period, are restricted to a single loading variable. Consequently, due to the "system wide" nature of the analysis, a defence's conditional failure probability must also be expressed in terms of a single loading in the form of a fragility curve. For coastal defences the single loading is the overtopping discharge, an amalgamation of these basic loading variables. The prevalence of other failure initiation mechanisms may vary considerably for combinations of the basic loadings which give rise to equal overtopping discharges. Hence the univariate nature of the existing representations potentially restricts their ability to accurately assess an asset's structural vulnerability. Secondly, they only consider failure at least partially initiated through overtopping and thus neglect other pertinent initiation mechanisms acting in its absence. Thirdly, fragility representations have been derived for 61 generic assets (idealised forms of the defences found around the UK coast) each in five possible states of repair. The fragility representation associated with the generic asset and its state of repair deemed to most closely resemble a particular defence is adopted to describe its fragility. Any disparity in the parameters which influence the defence's structural vulnerability in the generic form of the asset and those observed in the field are also likely to further reduce the robustness of the existing fragility representations. In NaFRA coastal flood defence assets are broadly classified as vertical walls, beaches and embankments. The latter are typically found in sheltered locations where failure is water level driven and hence expressing failure probability conditionally on overtopping is admissible. Therefore new fragility representations for vertical wall and gravel beach assets which address the limitations of those presently adopted in NaFRA are derived. To achieve this aim it was necessary to propose new procedures for extracting information on the site and structural parameters characterising a defence's structural vulnerability from relevant resources (predominately beach profiles). In addition novel statistical approaches were put forward for capturing the uncertainties in the parameters on the basis of the site specific data obtained after implementation of the aforementioned procedures. A preliminary validation demonstrated the apparent reliability of these approaches. The pertinent initiation mechanisms behind the structural failure of each asset type were then identified before the state-of-the-art models for predicting the prevalence of these mechanisms during an event were evaluated. The Obhrai et al. (2008) re-formulation of the Bradbury (2000) barrier inertia model, which encapsulates all of the initiating mechanisms behind the structural failure of a beach, was reasoned as a more appropriate model for predicting the breach of a beach than that adopted in NaFRA. Failure initiated exclusively at the toe of a seawall was explicitly accounted for in the new formulations of the fragility representations using the predictors for sand and shingle beaches derived by Sutherland et al. (2007) and Powell & Lowe (1994). In order to assess whether the new formulations warrant a place in future FRAs they were derived for the relevant assets in Lyme Bay (UK). The inclusion of site specific information in the derivation of fragility representations resulted in a several orders of magnitude change in the Annual Failure Probabilities (AFPs) of the vertical wall assets. The assets deemed most vulnerable were amongst those assigned the lowest AFPs in the existing analysis. The site specific data indicated that the crest elevations assumed in NaFRA are reliable. Hence it appears the more accurate specification of asset geometry and in particular the inclusion of the beach elevation in the immediate vicinity of the structure in the overtopping calculation is responsible for the changes. The AFP was zero for many of the walls (≈ 77%) indicating other mechanism(s) occurring in the absence of any overtopping are likely to be responsible for failure. Toe scour was found to be the dominant failure mechanism at all of the assets at which it was considered a plausible cause of breach. Increases of at least an order of magnitude upon the AFP after the inclusion of site specific information in the fragility representations were observed at ≈ 86% of the walls. The AFPs assigned by the new site specific multivariate fragility representations to the beach assets were positively correlated with those prescribed by the existing representations. However, once the new representations were adopted there was substantially more variability in AFPs of the beach assets which had previously been deemed to be in identical states of repair. As part of the work, the new and existing fragility representations were validated at assets which had experienced failure or near-failure in the recent past, using the hydraulic loading conditions recorded during the event. No appraisal of the reliability of the new representations for beaches was possible due to an absence of any such events within Lyme Bay. Their AFPs suggest that armed with more information about an asset's geometry the new formulations are able to provide a more robust description of a beach's structural vulnerability. The results of the validation as well as the magnitude of the AFPs assigned by the new representations on the basis of field data suggest that the newly proposed representations provide the more realistic description of the structural vulnerability of seawalls. Any final conclusions regarding the robustness of the representations must be deferred until more failure data becomes available. The trade-off for the potentially more robust description of an asset's structural vulnerability was a substantial increase in the time required for the newly derived fragility representations to compute the failure probability associated with a hydraulic loading event. To combat this increase, (multivariate) generic versions of the new representations were derived using the structural specific data from the assets within Lyme Bay. Although there was generally good agreement in the failure probabilities assigned to the individual hydraulic loading events by the new generic representations there was evidence of systematic error. This error has the potential to bias flood risk estimates and thus requires investigation before the new generic representations are included in future FRAs. Given the disparity in the estimated structural vulnerability of the assets according to the existing fragility curves and the site-specific multivariate representations the new generic representations are likely to be more reliable than the existing fragility curves.
14
BRUNELLI, ANDREA. "SEISMIC FRAGILITY CURVES ACCOUNTING FOR SITE AND SOIL STRUCTURE INTERACTION EFFECTS ON URM BUILDINGS." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1093913.
Full textAbstract:
Significant site-amplification effects have been observed in various historic centers following the recent seismic events in Italy (e.g., L'Aquila 2009, Emilia 2012, Central Italy 2016-17), but also examples of Soil Foundation Structure (SFS) interaction in ordinary unreinforced masonry (URM) buildings. In the past, SFS interaction effects were usually considered for masonry buildings only in slender or massive URM monumental structures. Following the latest observed evidence, this research aims to further investigate the role of site amplification and SFS interaction in the seismic response of URM residential structures. The final goal is to provide an effective procedure to consider these effects in large-scale risk assessment as well.
The first part of the research validated the numerical approach to analyze the SFS interaction by reproducing the seismic response of the Visso school affected by the earthquake sequence in central Italy. This school constituted a very emblematic case study, since it was permanently monitored by the Italian Department of Civil Protection and suffered very severe damage, allowing validation even in a highly nonlinear phase.
The procedure is based on the decoupled approach. Therefore, the input motion of the foundation is calculated from the site response analyses and the structural performance is analyzed through a structural model with springs at the base and characterized by equivalent damping. This school's validated procedure and numerical model were exploited to derive fragility curves that include site effects and SFS interaction under different subsurface conditions. The predicted damage probability was also compared with the results obtained from different amplifications of the simplified Code-compliant approach.
Finally, the research was further generalized by considering multiple building types and different soil profiles. The structural types were inspired by the most frequent building types in the municipality of Visso, consisting of aggregate masonry structures.
The set of derived fragility curves was finally applied to an urban scale to develop damage scenarios. In particular, the resulting damage under ground motion of the Central Italy earthquake was compared with that observed and predicted by existing faster and less accurate approaches, to assess the potential of the developed tools also to support possible future large-scale mitigation policies.
15
Hennion, Arnaud. "Microstructure et fragilisation des aciers de cuve des réacteurs nucléaires VVER 440." Lille 1, 1999. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1999/50376-1999-389.pdf.
Full textAbstract:
Les réacteurs nucléaires VVER 440 à eau pressurisée, comptent à ce jour 27 unités en fonctionnement en Europe de l’Est et en ex-URSS. Les cuves de ces réacteurs, en aciers faiblement alliés au Cr-Mo-V, se caractérisent par la présence d’un joint soudé circonférentiel en regard de la zone de cœur du réacteur. Le joint subit un flux neutronique important et contient des teneurs élevées en cuivre et phosphore, éléments réputés fragilisants sous irradiation. La cinétique de fragilisation des cuves s’en trouve accélérée, abrégeant l’espérance de vie des réacteurs. Afin d’acquérir des connaissances sur la microstructure et les propriétés mécaniques de ces aciers de cuve, des métaux de base, des ZAT et des zones fondues ont été étudiés. Les teneurs élevées en phosphore dans les zones fondues provoquent une fragilisation de revenu réversible pendant les revenus de post-soudage. La nature du dommage d’irradiation des zones fondues a été déterminée par des examens en diffusion des neutrons aux petits angles, en sonde atomique et en microscopie électronique en transmission. Des atmosphères de soluté d’un rayon proche du nanomètre, riches en cuivre et présentant des caractéristiques en partie identiques à celles présentes dans les aciers de cuve occidentaux sont mises en évidence. Une évolution de la distribution en taille de fins carbures de vanadium décorant la sous-structure de dislocations de ces aciers est également observée. Ces défauts disparaissent au cours des revenus de post-irradiation. Comme dans les aciers de cuve occidentaux, la fragilisation des aciers de cuve résulte de mécanismes de durcissement et de réduction de la cohésion des interfaces. La spécificité du dommage d’irradiation des aciers de cuve VVER 440 est principalement liée aux teneurs élevées en phosphore et à la présence d’une distribution dense de fins carbures de vanadium.
16
Avsar, Ozgur. "Fragility Based Seismic Vulnerability Assessment Of Ordinary Highway Bridges In Turkey." Phd thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610693/index.pdf.
Full textAbstract:
Recent devastating earthquakes revealed that bridges are one of the most vulnerable components of the transportation systems. These seismic events have emphasized the need to mitigate the risk resulting from the failure of the bridges. Depending on the seismicity of the bridge local site, seismic vulnerability assessment of the bridges can be done based on the fragility curves. These curves are conditional probability functions which give the probability of a bridge attaining or exceeding a particular damage level for an earthquake of a given intensity level. In this dissertation, analytical fragility curves are developed for the ordinary highway bridges in Turkey constructed after the 1990s to be used in the assessment of their seismic vulnerability. Bridges are first grouped into certain major bridge classes based on their structural attributes and sample bridges are generated to account for the structural variability. Nonlinear response history analyses are conducted for each bridge sample with their detailed 3-D analytical models under different earthquake ground motions having varying seismic intensities. Several engineering demand parameters are employed in the determination of seismic response of the bridge components as well as defining damage limit states in terms of member capacities. Fragility curves are obtained from the probability of exceeding each specified damage limit state for each major bridge class. Skew and single-column bent bridges are found to be the most vulnerable ones in comparison with the other bridge classes. Developed fragility curves can be implemented in the seismic risk assessment packages for mitigation purposes.
17
Dourado, Nuno Miguel. "R-Curve behaviour and size effect of a quasibrittle material : wood." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13734/document.
Full textAbstract:
Ce travail concerne des expériences mécaniques, des analyses numériques et des modélisations analytiques de la rupture cohésives (Mode I), vis-à-vis de l’étude du comportement mis en évidence par la courbe de Résistance (Courbe-R) et l’effet d’échelle de structures entaillées en bois massif. Des expériences de fissuration sont combinées à des analyses numériques pour déterminer les propriétés de rupture au moyen d’une procédure appelée Théorie de la Mécanique de la Rupture Linéaire Élastique équivalente (TMRLE), basée sur la complaisance de la structure. La courbe-R, obtenue à partir des expériences, selon une méthode de correction du poids propre, montre l’existence d’un domaine endommagé (Zone de Processus de Rupture) de taille non négligeable se développant en fond de fissure. Dans des conditions de fissuration stationnaire, ce domaine atteint une taille critique, et l’énergie nécessaire pour faire propager la fissure avec ce domaine endommagé (par unité de surface de rupture), reste constante. Le taux de libération de l’énergie de fissuration ainsi attendu, joue un rôle important en Mécanique de la Rupture, car il est possible simuler le comportement quasi-fragile du matériau en combinaison avec les autres propriétés de cohésion. La loi d’effet d’échelle de Bažant, utilisée pour prévoir l’influence de la taille sur la contrainte nominale, est estimée à partir de la réunion de deux comportements asymptotiques réalisés sur de petites tailles (Analyse limite ou RdM) et des grandes tailles. Une procédure analytique est présentée pour évaluer le comportement asymptotique additionnel exhibé par la contrainte nominale dans le régime intermédiaire, de façon plus exacte. Une validation numérique est présentée, et l’information expérimentale vient confirmer ce comportement asymptotiqueThis work concerns the mechanical testing, numerical analysis and modelling of cohesive fracture (Mode I) on the purpose to study the Resistance-curve behaviour and the size effect in wooden notched structures. The mechanical testing is combined with the numerical analysis to evaluate fracture properties by means of an equivalent LEFM approach based on the structure compliance. The Resistance-curve being revealed from the experiments, by means of a self-weight compensation method, correction puts into evidence that a non-negligible damaged domain (Fracture Process Zone) is under development in the crack front during the loading process. This being the case, among other fracture parameters issued from the Resistance-curve, the critical (asymptotic) energy release rate is determined, turning possible to use it in combination with other cohesive crack properties in the crack modelling (in Mode I). Thus, for a given geometry it is possible to monitor the critical dimension being revealed by the Fracture Process Zone (FPZ) during the crack propagation. The well known Bažant’s size effect law provides the scaling of the nominal strength through the asymptotic matching performed both on the small (Strength Theory) and on the large (LEFM) structure sizes. An analytical procedure is proposed to determine an additional asymptotic regime in the intermediate size range through a more accurate manner. Numerical validations of the proposed procedure are made and experimental data is presented revealing the scaling of the nominal strength through an envelop of values
18
Ramanathan, Karthik Narayan. "Next generation seismic fragility curves for california bridges incorporating the evolution in seismic design philosophy." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44883.
Full textAbstract:
Quantitative and qualitative assessment of the seismic risk to highway bridges is crucial in pre-earthquake planning, and post-earthquake response of transportation systems. Such assessments provide valuable knowledge about a number of principal effects of earthquakes such as traffic disruption of the overall highway system, impact on the regions' economy and post-earthquake response and recovery, and more recently serve as measures to quantify resilience. Unlike previous work, this study captures unique bridge design attributes specific to California bridge classes along with their evolution over three significant design eras, separated by the historic 1971 San Fernando and 1989 Loma Prieta earthquakes (these events affected changes in bridge seismic design philosophy). This research developed next-generation fragility curves for four multispan concrete bridge classes by synthesizing new knowledge and emerging modeling capabilities, and by closely coordinating new and ongoing national research initiatives with expertise from bridge designers.
A multi-phase framework was developed for generating fragility curves, which provides decision makers with essential tools for emergency response, design, planning, policy support, and maximizing investments in bridge retrofit. This framework encompasses generational changes in bridge design and construction details. Parameterized high-fidelity three-dimensional nonlinear analytical models are developed for the portfolios of bridge classes within different design eras. These models incorporate a wide range of geometric and material uncertainties, and their responses are characterized under seismic loadings. Fragility curves were then developed considering the vulnerability of multiple components and thereby help to quantify the performance of highway bridge networks and to study the impact of seismic design principles on the performance within a bridge class. This not only leads to the development of fragility relations that are unique and better suited for bridges in California, but also leads to the creation of better bridge classes and sub-bins that have more consistent performance characteristics than those currently provided by the National Bridge Inventory. Another important feature of this research is associated with the development of damage state definitions and grouping of bridge components in a way that they have similar consequences in terms of repair and traffic implications following a seismic event. These definitions are in alignment with the California Department of Transportation's design and operational experience, thereby enabling better performance assessment, emergency response, and management in the aftermath of a seismic event. The fragility curves developed as a part of this research will be employed in ShakeCast, a web-based post-earthquake situational awareness application that automatically retrieves earthquake shaking data and generates potential damage assessment notifications for emergency managers and responders.Errata added at request of advisor and approved by Graduate Office, March 15 2016.
19
Rafie, Nazari Yasamin. "Seismic Fragility Analysis of Reinforced Concrete Shear Wall Buildings in Canada." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36090.
Full textAbstract:
Damage observed after previous earthquakes indicates that a large number of existing buildings are vulnerable to seismic hazard. This research intends to assess seismic vulnerability of regular and irregular shear wall buildings in Canada, having different heights and different levels of seismic design and detailing. As seismic hazard is a probabilistic event, a probabilistic methodology has been adopted to assess the seismic vulnerability of the shear wall buildings. The proposed research encompasses a comprehensive fragility analysis for seismic vulnerability of shear wall buildings in Canada. The first phase of the investigation involves shear wall buildings with different heights (hence different structural periods), designed based on the 2010 National Building Code of Canada. The second phase involves shear wall buildings designed prior to 1975, representing pre-modern seismic code era. The third phase involves the evaluation of pre-1975 shear wall buildings with irregularities.
3-Dimensional simulations of the buildings were constructed by defining nonlinear modelling for shear wall and frame elements. These models were subjected to dynamic time history analyses conducted using Perform 3D software. Two sets of twenty earthquake records, compatible with western and eastern Canadian seismicity, were selected for this purpose. Spectral acceleration and peak ground acceleration were chosen as seismic intensity parameters and the first storey drift was selected as the engineering demand parameter which was further refined for irregular cases. The earthquake records were scaled to capture the structural behaviour under different levels of seismic excitations known as Incremental Dynamic Analysis. The resulting IDA curves were used as the input for seismic fragility analysis. Fragility curves were derived as probabilistic tools to assess seismic vulnerability of the buildings. These curves depict probability of exceeding immediate occupancy, life safety and collapse prevention limit states under different levels of seismic intensity.
20
Akansel, Vesile Hatun. "Fragility Of A Shear Wall Building With Torsional Irregularity." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613542/index.pdf.
Full textAbstract:
Buildings with torsional irregularity represent the main focus of many
current investigations. However, despite this volume of research, there is no
established framework that describes adequately the seismic vulnerability of
reinforced concrete shear wall systems. In this study, the three-dimensional
behavior of a particular shear-wall structure under earthquake effects was
examined with regard to the nonlinear behavior of the reinforced concrete
assembly and the parameters that characterize the structure exposed to seismic
motion for damage assessment.
A three story reinforced concrete shear-wall building was analyzed using
the finite element method based ANSYS software. The scaled model building was
subjected to shaking table tests at Saclay, France. The project was led by the
Atomic Energy Agency (CEA Saclay, France) under the &ldquoSMART 2008 Project.&rdquo
The investigation was conducted in two phases. In the first phase, the results of the finite element method and experiments were examined, and were reported in this study. For time history analysis, micro-modeling was preferred due to allowing inclusion the nonlinear effects of concrete and steel for analysis. The guiding parameters (acceleration, displacement, strain) of analytical results are compared with the corresponding values that were measured in the experiments to be able to quantify the validity of models and simulation. For the comparison of v the numerical model results with the experimental results FDE (Frequency Domain Error) method was used. After comparison of the numerical model results with the experimental results, the second phase of the SMART 2008 Project was undertaken. The second phase consisted of two parts summarized as &ldquo
Sensitivity Study&rdquo
and &ldquo
Vulnerability Analyses&rdquo
. However, in this report only the sensitivity study and fragility analyses will be reported. Sensitivity study was done to understand which parameters affect the response of the structure. Twelve parametric cases were investigated under two different ground motions. Different behavior parameters were investigated. The effective damping coefficient was found to affect the structural response at 0.2 g design level as well as at 0.6 g over-design level. At the design level, it was observed that elasticity modulus of concrete and additional masses on the specimen determined as effective on the calculated results. To derive the failure probabilities of this structure under various earthquake forces for the given limit states, fragility curves were obtained. Different seismic indicators such as PGA (Peak ground acceleration), PGV (Peak ground velocity), PGD (Peak ground displacement) and CAV (Cumulative absolute velocity) were used as seismic indicators and MISD (Maximum interstory drift) were used as damage indicator for fragility curves. In all 30 time history analyses were done. Regression analyses using least squares method were performed to determine the median capacity and its deviation. Correlation coefficients of the time history data versus fitted curves obtained from the regression analyses changes between 0.65 and 0.99. The lower cases were for PGD- MISD graphs. The scatter of the fragility curves calculated for each damage limit was slightly wider. HAZUS MH MR1 (2003) damage states were also used for the calculation of the fragility curves and compared with the SMART 2008 damage states.
21
Bélec, Gilbert. "Seismic Assessment of Unreinforced Masonry Buildings In Canada." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34301.
Full textAbstract:
Unreinforced masonry (URM) structures have shown tobe susceptible to significant
damage during strong earthquakes. Vulnerability assessment of URM buildings is needed so that appropriate mitigation strategies can be implemented. The existing Canadian practice consists of rapid seismic screening of buildings to assign priorities for further and more refined assessments, followed by refined analysis of individual critical buildings. The current seismic screening procedure, from 1992, is based on qualitative observations of seismic vulnerability, enabling the assignment of seismic priority indices, quantified on the basis of expert opinion and experience. More refined tools are needed for seismic vulnerability assessment of URM buildings in Canada, based on the current Canadian
seismic hazard values. The objective of the research project is to fulfill these needs by
developing fragility curves that provide a probabilistic assessment of different levels of
building performance under different intensities ofeastern and western seismicity.
Using an inventory of over 50,000 structures, a seismic assessment of typical low-rise and
mid-rise URM structures located in eastern and western Canada was carried out. The
required analyses were done using applied element method software which effectively
modeled the in-plane and out-of-plane behaviour of masonry walls. Using incremental
dynamic analysis, fragility curves were developed to reflect the capacity of URM
structures with a wide variety of selected structural and ground motion parameters. The
results were verified against available fragility information in the literature. They show the significance of selected parameters, while providing effective tools for seismic
vulnerability assessment of URM buildings in eastern and western Canada.
22
Ferreño, Blanco Diego. "Integridad estructural de vasijas nucleares en base a la curva patrón obtenida mediante probetas reconstruidas." Doctoral thesis, Universidad de Cantabria, 2008. http://hdl.handle.net/10803/10603.
Full textAbstract:
En esta tesis se ha caracterizado el acero, virgen e irradiado, de la vasija de una central nuclear española actualmente en servicio, en la región de temperaturas conocida como Zona de Transición Dúctil-Frágil. Para ello, se han ensayado probetas propias de la Mecánica de Fractura, reconstruidas a partir de mitades de probetas de impacto previamente ensayadas. Para describir la tenacidad a fractura en la Zona de Transición se ha empleado el modelo de la Curva Patrón.Finalmente, se ha analizado el impacto del procedimiento de caracterización y del modelo de la Curva Patrón sobre la Integridad Estructural de la vasija, comparando sus predicciones con las que se obtienen de aplicar los procedimientos convencionales que contempla la normativa vigente, representada por el Código ASME. En esta comparación se ha hecho uso del procedimiento FITNET de Integridad Estructural.In this thesis, the steel, virgin and irradiated, from the vessel of a Spanish Nuclear Plant currently operating, has been characterized in the range of temperatures known as Ductile to Brittle Transition Region. For this purpose, Fracture Mechanics specimens, reconstituted from halves of impact specimens previously broken, have been tested. To describe fracture toughness in the Transition Region, the Master Curve method has been used.Eventually, the influence of the characterization procedure together with the Master Curve method on the Structural Integrity of the vessel has been analyzed, comparing their predictions with those coming from applying conventional procedures proposed by the current regulations, represented by the ASME Code. In this comparison, the FITNET Structural Integrity procedure has been used.
23
Bowers, Matthew E. "Seismic fragility curves for a typical highway bridge in Charleston, SC considering soil-structure interaction and liquefaction effects." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1202500829/.
Full text
24
Mammone, Angelo. "Innovative probabilistic methodologies to assess seismic vulnerability of simple supported girder bridges." Doctoral thesis, Universita degli studi di Salerno, 2019. http://elea.unisa.it:8080/xmlui/handle/10556/4279.
Full textAbstract:
2017 - 2018Since the end of the eighties, numerous studies have been conducted analysing the relationship between the infrastructures and the economic development of the territory, highlighting its close correlation. In the last decades, the costs for the management and maintenance of these networks have increased considerably considering the age of the same and the increase in demand that has been witnessed. The phenomenon is particularly evident in some elements of transport networks such as bridges, viaducts and tunnels, which, as evidenced by the telluric events that have hit Italy in recent decades, have shown a high level of vulnerability also towards media events. Intensity. The problems encountered are essential because the Italian infrastructural network is constituted for the vast majority of bridges built in the 60s and 80s, structures conceived in seismic territories generally only afterwards and, therefore, without seismic engineering criteria. Furthermore, the lack of routine maintenance policies and practices has accentuated the decay of structural services in some cases. This thesis study focuses on the analysis of the efficiency of adaptation and improvement techniques for multi-span bridges simply supported, built in Italy in the 60s-80s, a simple bridge/viaduct suite was used. Defined according to the geometric and mechanical characteristics detected by the bridges built on the Italian motorway and road network. To evaluate the structural performance of bridges and viaducts, the probabilistic method from the basis of Performance Based Earthquake Engineering (PBEE) was used, in particular through the use of fragility curves. The purpose of bridging curves for bridges, however, shows some limitations, since they are complex structures composed of several structural elements that interact with each other, so it is difficult to determine the collapse mechanisms of the whole system. To simplify the comprehension of the global collapse mechanism, thus facilitating the general evaluation of the improvement proposals related to the single structural components, we propose an innovative method of analysis and graphic representation of the fragility curves. [edited by Author]
XXXI ciclo
25
Guimarães, Valdir Alves. "Determinação da temperatura de referência T0 da curva mestre na região de transição dúctil-frágil de aços ARBL /." Guaratinguetá : [s.n.], 2006. http://hdl.handle.net/11449/116078.
Full textAbstract:
Resumo: Materiais estruturais utilizados no projeto de equipamentos e instalações industriais podem apresentar mudança de seu comportamento à fratura quando se varia a temperatura. Este tipo de comportamento caracteriza-se pela existência de uma curva de transição, onde 3 regiões ficam bem definidas: os patamares inferior e superior e a região de transição. Na região de transição, os resultados experimentais apresentam alto espalhamento e são bastante dependentes da geometria ensaiada. Para solucionar este problema, foi desenvolvido um modelo analítico experimental, que resultou na edição da norma ASTM E1921-97. O trabalho inclui um estudo da influência de diversas rotas de tratamentos térmicos aplicadas em um aço 4130 utilizado pela indústria aeronáutica, um aço de qualidade API utilizado pela indústria petrolífera e um aço da classe A516 atualmente utilizado pela indústria nacional de vasos de pressão, na microestrutura, propriedades mecânicas de tração e tenacidade à fratura. Os resultados mostraram que o aço 4130 A450, apresentou a melhor correlação entre resistência e tenacidade entre as microestruturas pesquisadas. Este comportamento deve estar associado a rota de tratamento térmico aplicada a esta condição. O tratamento de austêmpera possibilita a formação de bainita que, tradicionalmente é conhecida por apresentar elevados valores de tenacidade. O método proposto pela ASTM pode ser considerado viável para as diversas microestruturas pesquisadas ampliando a aplicação da metodologia que recomenda o ensaio apenas para aços ferríticos. No entanto, a metodologia da Curva Mestra em materiais tratados termicamente deve ser conduzida de forma a se estabelecer parâmetros que considerem as modificações microestruturais sofridas pelo material.Abstract: Structural materials used in industrial equipments design can change fracture behavior when the temperature is varied. This type of behavior is characterized by the existence of a transition curve, where 3 areas are well defined: inferior and superior landings and the ductile brittle transition. In ductile brittle transition, experimental results present high scatter and depend highly of specimen geometry. In order to solve this problem, an analytical experimental model was developed, resulting in ASTM E1921-97 standard edition. This work includes the influence of several heat treatments analysis applied in a 4130 steel used by the aeronautical industry, a API X70 steel used by the line pipe industry and a ASTM A516 steel used by pressure vases national industry, where it was analyzed the influence in the microstructure, mechanical properties and fracture toughness. The results showed that the 4130 A450 steel presented the best correlation between resistance and toughness among the researched microstructures. This behavior should be associated with the heat treatment route applied. The isothermal quenching treatment makes possible bainite formation which, traditionally it is known by its high toughness values. The methodology proposed by ASTM is considered viable for the several researched microstructures enlarging the application of the methodology that just recommends the rehearsal for ferritics steels. However, Master Curve methodology in heat treated materials must have some parameters settling down considering the microstructure modifications suffered by the material.
26
Franco, Andrea. "A probabilistic approach to classify the levee reliability." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10120/.
Full textAbstract:
This work aims to evaluate the reliability of these levee systems, calculating the probability of “failure” of determined levee stretches under different loads, using probabilistic methods that take into account the fragility curves obtained through the Monte Carlo Method.
For this study overtopping and piping are considered as failure mechanisms (since these are the most frequent) and the major levee system of the Po River with a primary focus on the section between Piacenza and Cremona, in the lower-middle area of the Padana Plain, is analysed.
The novelty of this approach is to check the reliability of individual embankment stretches, not just a single section, while taking into account the variability of the levee system geometry from one stretch to another.
This work takes also into consideration, for each levee stretch analysed, a probability distribution of the load variables involved in the definition of the fragility curves, where it is influenced by the differences in the topography and morphology of the riverbed along the sectional depth analysed as it pertains to the levee system in its entirety.
A type of classification is proposed, for both failure mechanisms, to give an indication of the reliability of the levee system based of the information obtained by the fragility curve analysis.
To accomplish this work, an hydraulic model has been developed where a 500-year flood is modelled to determinate the residual hazard value of failure for each stretch of levee near the corresponding water depth, then comparing the results with the obtained classifications.
This work has the additional the aim of acting as an interface between the world of Applied Geology and Environmental Hydraulic Engineering where a strong collaboration is needed between the two professions to resolve and improve the estimation of hydraulic risk.
27
Ucer, Serkan. "Seismic Response And Vulnerability Assessment Of Tunnels:a Case Study On Bolu Tunnels." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615005/index.pdf.
Full textAbstract:
The aim of the study is to develop new analytical fragility curves for the vulnerability assessment of tunnels based on actual damage data of tunnels obtained from past earthquakes. For this purpose, additional important damage data belonging to Bolu Tunnels, Turkey was utilized as a case study.
Bolu Tunnels constitute a very interesting case from the earthquake hazard point of view, since two major earthquakes, 17 August 1999 Marmara and 12 November 1999 Düzce, occurred during the construction of the tunnels. The August 17, 1999 earthquake was reported to have had minimal impact on the Bolu Tunnels. However, the November 12, 1999 earthquake caused some sections of both tunnels to collapse. The remaining sections of the tunnels survived with various damage states which were subsequently documented in detail. This valuable damage data was thoroughly utilized in this study. To develop analytical fragility curves, the methodology described by Argyroudis et al. (2007) was followed. Seismic response of the Tunnels was assessed using analytical, pseudo-static and full-dynamic approaches. In this way, it was possible to make comparisons regarding the dynamic analysis methods of tunnels to predict the seismically induced damage. Compared to the pseudo-static and full-dynamic methods, the predictive capability of the analytical method is found to be relatively low due to limitations inherent to this method. The pseudo-static and full-dynamic solution results attained appear to be closer to each other and better represented the recorded damage states in general. Still, however, the predictive capability of the pseudo-static approach was observed to be limited for particular cases with reference to the full-dynamic method, especially for the sections with increasingly difficult ground conditions. The final goal of this study is the improvement of damage indexes corresponding to the defined damage states which were proposed by Argyroudis et al. (2005) based on the previous experience of damages in tunnels and engineering judgment. These damage indexes were modified in accordance with the findings from the dynamic analyses and actual damage data documented from Bolu Tunnels following the Dü
zce earthquake. Three damage states were utilized to quantify the damage in this study.
28
Huh, Jungwon, Quang Tran, Achintya Haldar, Innjoon Park, and Jin-Hee Ahn. "Seismic Vulnerability Assessment of a Shallow Two-Story Underground RC Box Structure." MDPI AG, 2017. http://hdl.handle.net/10150/625742.
Full textAbstract:
Tunnels, culverts, and subway stations are the main parts of an integrated infrastructure system. Most of them are constructed by the cut-and-cover method at shallow depths (mainly lower than 30 m) of soil deposits, where large-scale seismic ground deformation can occur with lower stiffness and strength of the soil. Therefore, the transverse racking deformation (one of the major seismic ground deformation) due to soil shear deformations should be included in the seismic design of underground structures using cost- and time-efficient methods that can achieve robustness of design and are easily understood by engineers. This paper aims to develop a simplified but comprehensive approach relating to vulnerability assessment in the form of fragility curves on a shallow two-story reinforced concrete underground box structure constructed in a highly-weathered soil. In addition, a comparison of the results of earthquakes per peak ground acceleration (PGA) is conducted to determine the effective and appropriate number for cost- and time-benefit analysis. The ground response acceleration method for buried structures (GRAMBS) is used to analyze the behavior of the structure subjected to transverse seismic loading under quasi-static conditions. Furthermore, the damage states that indicate the exceedance level of the structural strength capacity are described by the results of nonlinear static analyses (or so-called pushover analyses). The Latin hypercube sampling technique is employed to consider the uncertainties associated with the material properties and concrete cover owing to the variation in construction conditions. Finally, a large number of artificial ground shakings satisfying the design spectrum are generated in order to develop the seismic fragility curves based on the defined damage states. It is worth noting that the number of ground motions per PGA, which is equal to or larger than 20, is a reasonable value to perform a structural analysis that produces satisfactory fragility curves.
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Rana, Suman. "RISK-TARGETED GROUND MOTION FOR PERFORMANCE- BASED BRIDGE DESIGN." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2137.
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The seismic design maps on ASCE 7-05, International Building Code- 2006/2009, assumed uniform hazard ground motion with 2% probability of exceedance in 50 years for the entire conterminous U.S. But, Luco et al in 2007 pointed out that as uncertainties in collapse capacity exists in structures, an adjustment on uniform hazard ground motion was proposed to develop new seismic design maps. Thus, risk-targeted ground motion with 1% probability collapse in 50 years is adopted on ASCE 7-10. Even though these seismic design maps are developed for buildings, performance-based bridge design is done using same maps. Because significance difference lies on design procedure of buildings and bridges this thesis suggests some adjustment should be made on uncertainty in the collapse capacity(β) when using for bridge design. This research is done in 3 cities of U.S— San Francisco, New Madrid and New York. Hazard curve is drawn using 2008 version of USGS hazard maps and risk- targeted ground motion is calculated using equation given by Luco et al adjusting the uncertainty in collapse capacity(β) to be 0.9 for bridge design instead of 0.8 as used for buildings. The result is compared with existing result from ASCE 7-10, which uses β=0.6. The sample design response spectrum for site classes A, B, C and D is computed for all 3 cities using equations given in ASCE 7-10 for all β. The design response spectrum curves are analyzed to concluded that adjustment on uncertainty in collapse capacity should be done on ASCE 7-10 seismic design maps to be used for performance-based bridge design.
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Wang, Zhiyi. "évaluation du risque sismique par approches neuronales." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLC089/document.
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L'étude probabiliste de sûreté (EPS) parasismique est l'une des méthodologies les plus utiliséespour évaluer et assurer la performance des infrastructures critiques, telles que les centrales nucléaires,sous excitations sismiques. La thèse discute sur les aspects suivants: (i) Construction de méta-modèlesavec les réseaux de neurones pour construire les relations entre les intensités sismiques et les paramètresde demande des structures, afin d'accélérer l'analyse de fragilité. L'incertitude liée à la substitution desmodèles des éléments finis par les réseaux de neurones est étudiée. (ii) Proposition d'une méthodologiebayésienne avec réseaux de neurones adaptatifs, afin de prendre en compte les différentes sourcesd'information, y compris les résultats des simulations numériques, les valeurs de référence fournies dansla littérature et les évaluations post-sismiques, dans le calcul de courbes de fragilité. (iii) Calcul des loisd'atténuation avec les réseaux de neurones. Les incertitudes épistémiques des paramètres d'entrée de loisd'atténuation, tels que la magnitude et la vitesse moyenne des ondes de cisaillement de trente mètres, sontprises en compte dans la méthodologie développée. (iv) Calcul du taux de défaillance annuel en combinantles résultats des analyses de fragilité et de l'aléa sismique. Les courbes de fragilité sont déterminées parle réseau de neurones adaptatif, tandis que les courbes d'aléa sont obtenues à partir des lois d'atténuationconstruites avec les réseaux de neurones. Les méthodologies proposées sont appliquées à plusieurs casindustriels, tels que le benchmark KARISMA et le modèle SMARTSeismic probabilistic risk assessment (SPRA) is one of the most widely used methodologiesto assess and to ensure the performance of critical infrastructures, such as nuclear power plants (NPPs),faced with earthquake events. SPRA adopts a probabilistic approach to estimate the frequency ofoccurrence of severe consequences of NPPs under seismic conditions. The thesis provides discussionson the following aspects: (i) Construction of meta-models with ANNs to build the relations betweenseismic IMs and engineering demand parameters of the structures, for the purpose of accelerating thefragility analysis. The uncertainty related to the substitution of FEMs models by ANNs is investigated.(ii) Proposal of a Bayesian-based framework with adaptive ANNs, to take into account different sourcesof information, including numerical simulation results, reference values provided in the literature anddamage data obtained from post-earthquake observations, in the fragility analysis. (iii) Computation ofGMPEs with ANNs. The epistemic uncertainties of the GMPE input parameters, such as the magnitudeand the averaged thirty-meter shear wave velocity, are taken into account in the developed methodology.(iv) Calculation of the annual failure rate by combining results from the fragility and hazard analyses.The fragility curves are determined by the adaptive ANN, whereas the hazard curves are obtained fromthe GMPEs calibrated with ANNs. The proposed methodologies are applied to various industrial casestudies, such as the KARISMA benchmark and the SMART model
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Pappalardo, Rosario. "Studio dell’interazione terreno-struttura di un gasdotto soggetto a frana." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23763/.
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L’obiettivo di questo lavoro di tesi è analizzare l’interazione terreno-struttura di un gasdotto soggetto a frana. A tal fine si è realizzato un modello 3D che possa rappresentare l’interazione tra la frana del villaggio di Luozhentian (Hubei, Cina) e un tratto di condotta del gasdotto Sichuan – East.
Per questa frana sono infatti disponibili informazioni di dettaglio che possono essere utilizzate ai fini del lavoro di tesi.
Il modello tridimensionale è stato realizzato mediante l’impiego del software FLAC3D che ha permesso di visualizzare le modalità con cui la frana produce deformazioni alla condotta in termini di spostamenti, e di definire i punti in cui le sollecitazioni sono elevate e possono compromettere la tenuta della condotta.
I risultati dello studio possono fungere da riferimenti teorici ai fini del preallarme per gasdotti con caratteristiche simili e soggetti a fenomeni franosi.
Infine, è stata valutata la vulnerabilità delle condotte interrate soggette a deformazione permanente del terreno (PGD) mediante curve di fragilità.
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Perrault, Matthieu. "Evaluation de la vulnérabilité sismique de bâtiments à partir de mesures in situ." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00934454.
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L'objectif de cette thèse est d'analyser et de caractériser le lien entre les mouvements du sol et la réponse des bâtiments. En particulier, on s'intéresse à réduire les incertitudes qui entrent en jeu dans les méthodes de vulnérabilité, afin d'estimer plus précisément la vulnérabilité des structures au risque sismique. Pour ce faire, cette thèse est basée sur l'utilisation de données enregistrées au sein de bâtiments. Les enregistrements de vibrations ambiantes et de séismes de faibles amplitudes au sein de bâtiments permettent de caractériser le comportement élastique de ces structures. Des modèles peuvent ensuite être définis afin d'étudier les différentes composantes de la variabilité présente au sein des courbes de fragilité. On s'intéresse dans un premier temps au premier niveau de dommage, au-delà duquel les caractéristiques élastiques des bâtiments sont modifiées et les modèles définis ne sont plus valables. Des enregistrements de séismes ayant eu lieu depuis le début des années 1970 dans des bâtiments californiens sont ensuite utilisés. A partir de ces données, on a pu mettre en évidence des relations entre le déplacement au sein des structures et des paramètres décrivant la nocivité des signaux sismiques. Suivant l'indicateur utilisé pour représenter la nocivité des séismes, la réponse des bâtiments peut être estimée plus ou moins précisément. Notamment, les indicateurs faisant intervenir les paramètres dynamiques des bâtiments sont davantage liés avec la réponse des structures, représentée par son déplacement inter-étage moyen. La variabilité de la réponse des bâtiments peut être améliorée en regroupant les bâtiments par typologies (définies suivant leur matériau principal de construction et leur hauteur). En apportant davantage d'informations sur les structures, on peut ainsi diminuer la composante épistémique de la variabilité. De plus, en combinant des indicateurs de nocivité, on peut améliorer la précision pour la prédiction de la réponse de la structure. Une forme fonctionnelle est ainsi proposée afin d'estimer le déplacement inter-étage moyen au sein des structures, pour plusieurs typologies de bâtiments, à partir de quatre indicateurs de nocivité. Cette forme fonctionnelle est utilisée pour établir des courbes de fragilité et peut également être utilisée afin de donner une première estimation des dommages à la suite d'un séisme, en comparant les valeurs de déformations inter-étages avec des valeurs de référence (FEMA, 2003). Enfin, une méthode hybride est proposée pour la construction de courbes de fragilité, faisant intervenir un modèle de comportement non linéaire. Les paramètres de ce modèle sont définis de telle sorte que la réponse du modèle s'ajuste aux enregistrements de séismes effectués dans les bâtiments. Ce modèle est ensuite utilisé pour évaluer les composantes d'incertitudes et pour construire des courbes de fragilité pour tous les niveaux de dommages.
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Gangnant, Alexandre. "Étude de la rupture quasi-fragile d’un béton à l’échelle mésoscopique : aspects expérimentaux et modélisation." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0401/document.
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Le béton présente une rupture quasi-fragile du fait de la présence d’une zone d’élaboration de la rupture principalement microfissurée et de taille conséquence, se développant en avant du front de fissure. L’objectif de ces travaux consiste à mettre en évidence le processus d’évolution de la zone d’élaboration et l’étendue de cette dernière, et ce, sur la base d’une campagne d’essai Wedge Splitting suivie de simulations numériques aux éléments-finis utilisant le modèle d’endommagement isotrope de Fichant – La Borderie à l’échelle mésoscopique. Expérimentalement, les courbes de résistance obtenues dans le cadre de la Mécanique Linéaire Élastique de la Rupture équivalente attestent d’un phénomène de confinement précoce de la zone d’élaboration manifestement lié à la géométrie testée et aux propriétés du béton étudié.Les simulations numériques obtenues sur la base du modèle d’endommagement sont en accord avec les résultats expérimentaux et conduisent également à soupçonner ce phénomène de confinement. Par la suite, la simulation numérique est à nouveau utilisée sur cette même géométrie de spécimen mais en réduisant les propriétés de rupture de la matrice cimentaire afin de diminuer la taille de la zone d’élaboration. Les résultats de cette nouvelle simulation montrent un développement libre de la zone d’élaboration suivie d’une propagation auto-similaire de la fissure principale attestée par la présence d’un régime plateau de la courbe de résistance correspondante.Une analyse détaillée du champ d’endommagement puis du champ d’énergie restituée est réalisée et permet de mettre en évidence un critère de développement de la zone d’élaboration fondée sur une valeur maximale du taux local de restitution d’énergie d’endommagementConcrete exhibits a quasibrittle fracture due to the existence of a large fracture process zone (FPZ), mainly microcracked, which develops ahead of the crack front. The aim of the current work consists in highlighting the FPZ development and its extent. For that purpose,an experimental campaign using Wedge Splitting Test was carried out and followed by finite element simulation using Fichant – La Borderie isotropic damage model acting at the mesoscale of concrete. Experimental analysis exhibits that by the use from Resistance curves estimated in the framework of equivalent Linear Elastic Fracture Mechanics, the used geometry combined to the studied concrete properties are subjected to a confinement of FPZ. Numerical simulations achieved by the damage model are in agreement with experimental results and also seem to show FPZ confinement. There after, numerical simulations are used again on the same specimen geometry but by decreasing fracture properties of cementitious matrix, in order to minimize the FPZ size. Numerical results exhibit that the FPZ was now freely developed and followed by a self-similar propagation of the main crack as shown by the existence of a “plateau” value on the corresponding Resistance curve. A numerical analysis is performed and leads to the propositionof a FPZ development criteria based on a maximal value of the local damage energy release rate
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Salamida, Gianluca. "Valutazione della vulnerabilità sismica del patrimonio edilizio emiliano: strutture a telaio in c.a. e influenza dei tamponamenti." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Find full textAbstract:
Il presente elaborato intende trattare il tema della vulnerabilità sismica del patrimonio edilizio esistente con riferimento agli edifici residenziali presenti in Emilia, caratterizzati da struttura a telaio in calcestruzzo armato con tamponamenti in muratura. L'obiettivo primario è la costruzione di curve di fragilità per via numerica, al fine di correlare una misura di intensità sismica alla probabilità di ottenere i vari livelli di danno previsti dalla scala macrosismica EMS-98. Parte del lavoro è incentrato sulla modellazione dei telai in c.a. irrigiditi da tamponamenti in muratura, al fine di valutarne l'interazione e possibili crisi fragili. Le curve di fragilità sono state ottenute per via numerica a partire da un set di analisi statiche non lineari su edifici di precedentemente definiti e dimensionati, allo scopo di renderli rappresentativi della parte più vulnerabile del patrimonio edilizio presente sul territorio.
Si è infine operato un confronto tra lo scenario di danno previsto sulla base delle curve di fragilità e il danno effettivamente osservato a seguito degli eventi sismici che nel maggio del 2012 hanno colpito l'Emilia.
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TELESCA, ALESSIO. "ADVANCED MODELLING OF OVER-STROKE DISPLACEMENT CAPACITY FOR CURVED SURFACE SLIDER DEVICES." Doctoral thesis, Università degli studi della Basilicata, 2022. http://hdl.handle.net/11563/153765.
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This doctoral dissertation aims to report on the research work carried out and to provide a contribution to the field of seismic base isolation. Since its introduction, the base isolation strategy proved to be an effective solution for the protection of structures and their components from the earthquake-induced damage, enhancing their resilience and implying a significative decrease in time and cost of repair compared to a conventional fixed-base structure.
Sliding isolation devices feature some important characteristics, over other devices, that make them particularly suitable for the application in the existing buildings retrofit such as the high displacements capacity combined with limited plan dimensions. Even though these devices diffusion has gotten more popular worldwide in last years, a full understanding of their performances and limits as well as their behaviour under real seismic excitations has not been yet completely achieved. When Curved Surface Sliders reach their displacement capacity, they enter the so-called over-stroke sliding regime which is characterized by an increase in stiffness and friction coefficient. While in the over-stroke displacements regime, anyways, sliding isolators are still capable, until certain threshold values, of preserving their ability to support gravity loads.
In this doctoral dissertation, the analysis of Curved Surface Sliding devices influence on different structures and under different configurations is presented and a tool for to help professionals in the design phase is provided. The research main focuses are: i) the numerical investigation of the over-stroke displacement influence on base isolated structures; ii) the numerical investigation of displacement retaining elements influence on base isolated structures; iii) the development of a mechanical model and an algebraic solution describing the over-stroke sliding regime and the associated limit displacements.
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Ceran, H. Burak. "Seismic Vulnerability Of Masonry Structures In Turkey." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612745/index.pdf.
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This study focuses on the evaluation of seismic safety of masonry buildings in Turkey by using fragility curves. Fragility curves for masonry buildings are generated by two behavior modes for load bearing walls: in-plane and out-of-plane. By considering the previous research and site investigations, four major parameters have been used in order to classify masonry buildings with in-plane behavior mode. These are number of stories, strength of load-bearing wall material, regularity in plan and the arrangement of walls (required length, openings in walls, etc.). In addition to these four parameters, floor type is also taken into account for the generation of fragility curves by considering out-of-plane behavior mode. During generation of fragility curves, a force-based approach has been used. In this study there exist two limit states, or in other words three damage states, in terms of base shear strength for in-plane behavior mode and flexural strength for out-of-plane behavior mode. To assess the seismic vulnerability of unreinforced masonry buildings in Turkey, generated fragility curves in terms of in-plane behavior, which is verified by damage statistics obtained during the 1995 Dinar earthquake, and out-of-plane behavior, which is verified by damage statistics obtained during the 2010 Elazig earthquake, is combined. Throughout the analysis, ground motion uncertainty, material variability and modeling uncertainty have also been considered. In the final part of the study, a single-valued parameter, called as &lsquovulnerability score&rdquo
, has been proposed in order to compare the seismic safety of unreinforced masonry buildings in Fatih sub province of Istanbul and to assess the influence of out-of-plane behavior together with the in-plane behavior of these existing masonry buildings.
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Al, Mamun Abdullah. "Seismic Damage Assessment of Reinforced Concrete Frame Buildings in Canada." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36188.
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The emphasis on seismic design and assessment of reinforced concrete (RC) frame structure has shifted from force-based to performance-based design and assessment to accommodate strength and ductility for required performance of building. RC frame structure may suffer different levels of damage under seismic-induced ground motions, with potentials for formation of hinges in structural elements, depending on the level of stringency in design. Thus it is required to monitor the seismic behaviour and performance of buildings, which depend on the structural system, year of construction and the level of irregularities in the structural system. It is the objective of the current research project to assess seismic performance of RC frame buildings in Canada, while developing fragility curves as analytical tools for such assessment. This was done through dynamic inelastic analysis by modelling selected building structures and using PERFORM-3D as analysis software, while employing incremental dynamic analysis to generate performance data under incrementally increasing seismic intensity of selected earthquake records. The results lead to probabilistic tools to assess the performance of buildings designed following the National Building Code of Canada in different years of construction with and without irregularities. The research consists of three phases; i) regular buildings designed after 1975, ii) regular buildings designed prior to 1975, and iii) irregular buildings designed prior to 1975. The latter two phases address older buildings prior to the development of modern seismic building codes. All three phases were carried out by selecting and designing buildings in Ottawa, representing the seismic region in eastern Canada, as well as buildings in Vancouver, representing the seismic region in western Canada. Buildings had three heights (2; 5; and 10-stories) to cover a wide range of building periods encountered in practice. The resulting fragility curves indicated that the older buildings showed higher probabilities of exceeding life safety and/or collapse prevention performance levels. Newer buildings showed higher probabilities of exceeding target performance levels in western Canada than those located in the east.
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Serhal, Jamil. "Étude de la vulnérabilité des bâtiments en maçonnerie soumis à des mouvements de terrains et élaboration de critères d’évolution de leur rigidité." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0024/document.
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L’objectif principal de cette recherche est l’étude du dommage des bâtiments en maçonnerie subissant des tassements différentiels. Cette contribution, en s’appuyant sur la modélisation numérique, les méthodes analytiques et sur l’expérimentation, vise à une meilleure compréhension du comportement des structures en maçonnerie. Ce problème trouve diverses applications en ingénierie avec par exemple les maisons situées dans des zones de creusement de tunnels, ou des zones subissant des affaissements de terrains. L’étude bibliographique met en évidence la diversité des méthodes permettant de catégoriser le dommage des bâtiments subissant des tassements. La cohérence de ces méthodes est étudiée. En particulier, le travail porte sur l’étude de l’influence des propriétés mécaniques des bâtiments sur les valeurs seuils proposées pour catégoriser le dommage. Une étude de sensibilité est mise en œuvre afin de proposer des intervalles de seuils dépendant des propriétés des bâtiments. Cette incertitude est alors formalisée par le développement de courbes de fragilité permettant de quantifier en terme de probabilité la sévérité du dommage pour différents types de bâtiments. En addition, la rigidité des bâtiments subissant des mouvements de terrains est un paramètre important pour étudier les phénomènes d’interaction sol-structure et évaluer les tassements différentiels transmis par le terrain aux structures. L’évolution de cette rigidité en fonction du dommage associé aux tassements n’est pas étudiée dans la littérature. Une méthodologie d’étude de la variation de la rigidité des bâtiments en maçonnerie en fonction du tassement transmis a été développée au moyen de modélisations numérique (logiciel UDEC). Des formulations analytiques sont alors proposées pour relier la réduction de la rigidité des bâtiments en fonction du tassement subis et de leurs propriétés. Une procédure expérimentale est mise en place afin de valider la méthodologique numérique. En conclusion, les deux principales contributions de cette thèse sont 1) une amélioration de l’évaluation du dommage des bâtiments en fonction de leurs propriétés, au moyen des courbes de fragilité et 2) le développement d’une méthodologie numérique permettant d’évaluer l’évolution de la rigidité des bâtiments en maçonnerie en fonction du tassement qu’ils subissent et en fonction de leurs propriétésThe main purpose of this research is the assessment of the damage of masonry buildings undergoing differential settlements. This contribution, which is based on numerical modeling, analytical methods and experimentation, aims for a better understanding of the behavior of masonry structures. The treated issue may be applied in different engineering fields, as for example the case of buildings located in tunneling areas or in areas suffering land subsidence. The bibliography survey presents a diversity of methods to categorize the damage of buildings undergoing settlement. This variety of methods, parameters and thresholds used to qualify the severity of the damage, prompted us to study the consistency of these methods, and the effect of the properties of masonry buildings - undergoing ground movements - on proposed threshold values. A sensitivity analysis on building properties is implemented in order to propose thresholds values intervals that depend on buildings properties. This uncertainty is then taken into account with the development of fragility curves that aim quantifying the damage in terms of probability according to a typology of buildings. In addition, the stiffness of buildings undergoing ground movements plays a very important role in studying the phenomenon of soil-structure interaction. However, the evolution of the stiffness of the damaged building due to settlements is not investigated in the literature. Numerical modeling (UDEC) is used to develop a methodology for the study of the stiffness variation of masonry buildings in relation to he settlement suffered by the structure. Analytical formulations are proposed to relate the reduction of the stiffness of the buildings with regard to the suffered settlement, and depending on the buildings properties. Some experimental tests are performed to validate the numerical methodology. Finally, the two mains results are 1) improvement in the assessment of buildings damage with the drawn of fragility curves and 2) the numerical methodology to formulate the changes in the stiffness of masonry buildings according to the suffered settlement, and according to their properties
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Limoge, Claire. "Méthode de diagnostic à grande échelle de la vulnérabilité sismique des Monuments Historiques : Chapelles et églises baroques des hautes vallées de Savoie." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN014/document.
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L’objectif de ce travail est de proposer une méthode d’analyse de vulnérabilité sismique adaptée à l’étude d’un patrimoine historique complet très étendu, indépendamment de la renommée de chaque bâtiment. En effet la grande vulnérabilité sismique du patrimoine ancien, très souvent en maçonnerie, impose, afin d’éviter tout dommage irréparable, de se donner les moyens d’intervenir en amont. Notre démarche doit donc répondre à trois impératifs principaux: développer des outils de choix à grande échelle afin de hiérarchiser les besoins, offrir une analyse pertinente du comportement sous séisme d'une structure historique maçonnée même en première approche, et trouver des méthodes pour gérer le nombre important d’incertitudes qui caractérise le diagnostic des édifices anciens. Pour ce faire, nous étudions les églises et chapelles baroques des hautes vallées de la Savoie française, témoignages d'une période particulièrement prospère dans l'histoire de la Savoie et d'un mouvement artistique unique dans un environnement hostile. Dans ce contexte nous avons donc développé ou adapté différents outils afin de pouvoir traiter les particularités des édifices anciens et utiliser pour des édifices anciens en maçonnerie rustique les potentialités des techniques proposées pour les édifices modernes : modélisations numériques non-linéaires dynamiques temporelles, mesures vibratoires in-situ, analyse multi modale non-linéaireThe aim of this thesis is to propose a seismic vulnerability assessment method well suited to the study of a complete historical heritage, regardless of the prestige of each building. Indeed the great seismic vulnerability of the historical heritage, often in masonry, requires to act preventively in order to avoid irreparable damage. Our approach must tackle three main requirements: to develop large-scale tools of choice to prioritize the needs, to provide relevant analysis of seismic behavior on the structural scale even in the first study, and to manage the large number of uncertainties characterizing the old buildings structural assessment. To this aim, we study the baroque churches and chapels in the high valleys of the French Savoie. They witness to a particularly prosperous period in the history of Savoy and a unique artistic movement adapted to a harsh environment. In this context we have therefore developed or adapted different tools in order to handle the peculiarities of the old buildings. This way we can use the today proposed techniques for modern buildings to study these ancient buildings in rustic masonry: non-linear temporal dynamics numerical modeling, vibratory in situ measurements, non-linear multi modal analysis
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Curi, Lorenzo. "Valutazione del rischio idraulico, compreso il fallimento delle difese, mediante metodo probabilistico: rottura del Secchia del 19 gennaio 2014." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10093/.
Full textAbstract:
Obbiettivo della tesi è sviluppare un metodo che valuti la probabilità di rottura arginale nella stesura delle mappe di pericolosità e di rischio alluvione. Ad oggi le mappe di pericolosità, redatte dagli enti regionali, considerano solo la probabilità di superamento dell’argine da parte del livello idrico (overtopping) e non il cedimento dello stesso a causa dell’instabilizzazione dovuta all’innalzamento del livello del fiume. Per la presente tesi si è scelto come caso di studio la rottura dell’argine destro del fiume Secchia del 19 gennaio 2014, presso la frazione di San Matteo, comune di Modena. Questo caso di rottura arginale è particolarmente interessante, poiché dopo l’accaduto la regione Emilia-Romagna ha predisposto una commissione tecnica per valutare le cause dell'evento. La commissione ha quindi predisposto una serie di indagini i cui dati saranno di fondamentale importanza nella presente tesi. Utilizzando, infatti, questo caso di cedimento arginale come esempio si è potuto innanzitutto ricostruire il fenomeno che ha provocato il fallimento dell’argine e ricalcolare il rischio inondazione sulle zone allagate considerando la probabilità di fallimento del sistema arginale.
Per fare ciò, si sono inizialmente eseguite varie modellazioni idrauliche, sul corpo arginale, per stabilire gli spostamenti della tavola d’acqua e i valori di pressione interstiziale dei pori al variare dei tiranti idrici utilizzando il software SEEP/W. Successivamente si è utilizzato SLOPE/W allo scopo di verificate le probabilità di cedimento dell'argine in relazione alle modellazioni idrauliche effettuate con SEEP/W. Una volta ricavate le probabilità di rottura alle varie quote idriche con SLOPE/W, le si è riportate su un foglio di calcolo Excel e ricavata la curva di fragilità dell'argine e calcolato le probabilità di accadimento degli eventi alluvionali. Dopo di ciò attraverso l’utilizzo del software CA2D si sono modellate le mappe di alluvione per i vari eventi e con l’ausilio di Qgis si sono ricavate le mappe di pericolosità e calcolato il rischio sugli edifici interessati.
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Lijiao, Yang. "A Methodology for Estimating Business Interruption Losses to Industrial Sectors due to Flood Disasters." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/202745.
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Popolizio, Stefano. "Valutazione delle incertezze sulla risposta sismica di telai in CA al variare di Modello Costitutivo e Modalità di Collasso." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14496/.
Full textAbstract:
L’obiettivo della tesi è di valutare, nei risultati di un’analisi sismica, l'incidenza dell’incertezza data dalla scelta del legame costitutivo in tre differenti modalità di collasso. Si studia quanto sia importante la scelta di un legame costitutivo, per la descrizione delle cerniere plastiche, ai fini di una maggiore precisione nella risposta della struttura. Per cui, una volta definita la struttura e scelto un set di accelerogrammi, si effettua un’analisi incrementale dinamica andando a cambiare, per ogni analisi, il legame costitutivo. Questo procedimento è stato ripetuto per le tre modalità di collasso definite. La scelta di quali legami costitutivi non lineari andare ad utilizzare è frutto di prove ed indagini sperimentali. I risultati ottenuti dall'analisi, in termini di curve IDA, sono stati rielaborati statisticamente per ricavare sia le curve di fragilità, per valutare la probabilità che l’edificio stesso raggiunga un particolare stato limite definito, e sia una risposta sulla valutazione dell’incertezza legata al legame costitutivo, tramite un’analisi di varianza detta Anova. In particolare gli stati limite utilizzati sono: stato limite di collasso (5% I.D.), stato limite di salvaguardia della vita umana (3% I.D.) e stato limite di danno limitato (1% I.D.). Dopodiché sono state confrontate le varianze derivate dall'incertezza nella scelta dell'input sismico e l'incertezza nella scelta del legame costitutivo, per capire quale sia l'incidenza di una rispetto all'altra.
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Chilaka, Neelesh. "Applications of water network tool for resilience (WNTR) for metrics and repair strategies of water distribution systems." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/24196/.
Full textAbstract:
Drinking water systems will always face multiple challenges with respective to aging infrastructure, concerns related to water quality, uncertainty in supply and demand, disruptive events like environmental urgencies, natural disasters, and cyber and terrorist attacks. All of the above-mentioned incidents have the potential to disrupt a large part of a water system or the whole water distribution system either causing the damage to vital parts of infrastructure, affecting the human health, and interrupting service to consumers.Urban or metropolitan communities have experienced loss of infrastructure or its primary functionality in the corollary of the disasters. The coincidence of earthquakes and densely populated cities shall create the potential for increased direct and indirect consequences of seismic events with respective to all infrastructure elements would be at halt until the recovery time they need for full recovery.
The resilience of all the communities to disasters is a component of the execution of infrastructure and their functionality is to be analysed. Water supply networks in the corollary of disasters offer primary assistance to enable, safeguard and improve the conditions for time being. Any interruption in these frameworks will cause inconvenience and challenges for the disrupted network community. Providing enough water at acceptable levels of service in disasters is significant.
The resilience metrics must be determined for the better outcome of the analysis for a better analogy of the work being done for the research. The resilience of the water supply network would be indeterminable accurately since the real- world parameters change from time to time. This dissertation would be using a Python based tool which is Water Network tool for the resilience metrics determination of the water supply network.
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SANCIN, LJUBA. "SEISMIC VULNERABILITY EVALUATION OF R.C. AND MASONRY BUILDINGS IN THE CENTRE OF GORIZIA." Doctoral thesis, Università degli Studi di Trieste, 2021. http://hdl.handle.net/11368/2998137.
Full textAbstract:
The aim of this research study is to investigate the vulnerability of the building heritage in Gorizia, a town in north-eastern Italy, on the border with Slovenia. This town has not been considered seismic until the year 2003 and then in 2010 it has been classified in a higher seismicity class. For this reason, most of the buildings are not designed to resist seismic action at all and an even lower percentage fulfils the requirements of the current technical standard.
Four real existing buildings are analysed as case study buildings, representative of the main structural types that can be found in the town. Two of them are high - rise (11 and 12 storeys) reinforced concrete (RC) framed buildings with a brittle concrete stairwell, designed for gravitational load only and built in the 60’s-70’s. In the last years, a growing attention has been payed to the seismic vulnerability of existing RC framed structures, but this type of buildings, with a core of concrete walls, has been investigated much less, although it is a structural type that is very spread. The other two case studies are masonry buildings built in 1740 and in 1903, respectively. One of the masonry buildings is the city hall of Gorizia, on which many in-situ tests have been performed within a project of the Department of Engineering and Architecture with the Municipality of Gorizia. For both RC buildings, some considerations are made about the influence of the masonry infills on the seismic behaviour of the building and of the numerical model. The vibration periods found with numerical modelling are also compared to the periods evaluated with vibrational measurements. The two numerical models without infills are then analysed with non-linear static and dynamic analyses. The results are processed with a cloud analysis in order to calculate fragility curves of the buildings, that show a very brittle behaviour. The two masonry buildings are analysed also with pushover analysis.
For the evaluation of the seismic vulnerability of the analysed buildings, two types of seismic hazard assessments have been considered for the extraction of the seismic inputs: Probabilistic Seismic Hazard Assessment (PSHA) method, by the Italian code response spectra and Neo Deterministic Seismic Hazard Assessment (NDSHA) method, with response spectra of two specific possible scenarios for the town of Gorizia. The physics-based scenarios are calculated for the two faults that are the closest to Gorizia: Idrija and Medea. A comparison is made between the demand given by the seismic inputs defined with the two methods. The importance of using both methods for the design of low-damage retrofitting solutions is highlighted.
At last, a theoretical study has been carried out within the present research study in order to find an innovative and effective solution for the retrofit of the RC high-rise brittle buildings. It consists in the application of an exo - or endo - skeleton, with the additional introduction of a sliding system at the base of the RC building, in order to decouple its motion from the ground motion. In this way, the exo- or endo-skeleton can be designed independently from the features of the existing building, that remains undamaged. The characteristics of the exo/endo-skeleton can be calibrated on the seismic input of the site of interest, with the possibility to adapt it to new seismic classifications of the territory.The aim of this research study is to investigate the vulnerability of the building heritage in Gorizia, a town in north-eastern Italy, on the border with Slovenia. This town has not been considered seismic until the year 2003 and then in 2010 it has been classified in a higher seismicity class. For this reason, most of the buildings are not designed to resist seismic action at all and an even lower percentage fulfils the requirements of the current technical standard. Four real existing buildings are analysed as case study buildings, representative of the main structural types that can be found in the town. Two of them are high - rise (11 and 12 storeys) reinforced concrete (RC) framed buildings with a brittle concrete stairwell, designed for gravitational load only and built in the 60’s-70’s. In the last years, a growing attention has been payed to the seismic vulnerability of existing RC framed structures, but this type of buildings, with a core of concrete walls, has been investigated much less, although it is a structural type that is very spread. The other two case studies are masonry buildings built in 1740 and in 1903, respectively. One of the masonry buildings is the city hall of Gorizia, on which many in-situ tests have been performed within a project of the Department of Engineering and Architecture with the Municipality of Gorizia. For both RC buildings, some considerations are made about the influence of the masonry infills on the seismic behaviour of the building and of the numerical model. The vibration periods found with numerical modelling are also compared to the periods evaluated with vibrational measurements. The two numerical models without infills are then analysed with non-linear static and dynamic analyses. The results are processed with a cloud analysis in order to calculate fragility curves of the buildings, that show a very brittle behaviour. The two masonry buildings are analysed also with pushover analysis. For the evaluation of the seismic vulnerability of the analysed buildings, two types of seismic hazard assessments have been considered for the extraction of the seismic inputs: Probabilistic Seismic Hazard Assessment (PSHA) method, by the Italian code response spectra and Neo Deterministic Seismic Hazard Assessment (NDSHA) method, with response spectra of two specific possible scenarios for the town of Gorizia. The physics-based scenarios are calculated for the two faults that are the closest to Gorizia: Idrija and Medea. A comparison is made between the demand given by the seismic inputs defined with the two methods. The importance of using both methods for the design of low-damage retrofitting solutions is highlighted. At last, a theoretical study has been carried out within the present research study in order to find an innovative and effective solution for the retrofit of the RC high-rise brittle buildings. It consists in the application of an exo - or endo - skeleton, with the additional introduction of a sliding system at the base of the RC building, in order to decouple its motion from the ground motion. In this way, the exo- or endo-skeleton can be designed independently from the features of the existing building, that remains undamaged. The characteristics of the exo/endo-skeleton can be calibrated on the seismic input of the site of interest, with the possibility to adapt it to new seismic classifications of the territory.
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FREDDI, FABIO. "Local engineering demand parameters for seismic risk evaluation of low ductility reinforced concrete buildings." Doctoral thesis, Università Politecnica delle Marche, 2012. http://hdl.handle.net/11566/242022.
Full textAbstract:
The damage occurred during recent earthquakes in many existing reinforced concrete (RC)
buildings designed before the introduction of modern anti-seismic codes has shown that
these structures are very vulnerable to the seismic action due to their reduced ductility
capacity. This underlines the need to develop retrofit techniques for reducing the
vulnerability of existing structures and of reliable tools for assessing the effectiveness of
the retrofit and the resulting structural safety. Earthquake risk mitigation and seismic risk
evaluation are among the engineering's most complex challenges. Seismic risk evaluation
must include a proper assessment of the system vulnerability and seismic hazard. Seismic
vulnerability analysis of structural systems can be a rather hard task especially, amongst
others, due to the high degree of uncertainty affecting the system properties, the capacity
and the input definition and hence should be performed within a probabilistic framework.
The Performance Based Earthquake Engineering (PBEE) framework introduced by the
Pacific Earthquake Engineering Research Centre (PEER) is currently the more advanced
probabilistic methodology adopted in seismic engineering. The effort of many researchers
has been employed along the last decades to reach the present state of development,
however, there are still drawbacks in the design and seismic performance assessment of
certain type of structures.
The objective of this Thesis is to investigate the probabilistic response and vulnerability of
a class of low ductility reinforced concrete (RC) frame buildings and investigates about the
use of buckling retrained braces as retrofit technique. Traditionally, structural response is
measured by Engineering Demand Parameters (EDPs), such as the overall maximum
interstory drift over the height of the building. The use of this EDP is adequate to describe
the seismic response of ductile frame designed by strength hierarchy rules, but may lead to
a high approximation in the vulnerability evaluation since in this case there is not direct
relation between local failure mechanism and global interstory drifts. To obtain a more
thorough characterization of the vulnerability of the structure, a multi-component fragility
study is necessary, hence, the use of local EDP is investigated in order to enable a more
realistic and thorough description of the failure mechanisms for structural vulnerability.
The study proposes an optimized methodology for the probabilistic evaluation of seismic
demand of low ductility RC frames by exploring a range of intermediate, local and global
EDPs, identifying appropriate regression models and comparing performances of different
ground motion intensity measures used in the probabilistic analysis. In particular, different
EDPs are considered in order to highlight the most significant failure modalities in RC lowductility
frame buildings, optimal PSDMs of single components are developed for various
EDPs, and the viability of alternative IMs is explored. While the form of PSDMs and
efficiency of various IMs has been readily explored for global response parameters of RC
buildings, this study provides insight into the form of regression model appropriate for such
local and intermediate level EDPs as steel and concrete strains, moments and shears on
beams and columns, and global responses such as base shear or story accelerations. Furthermore, ground motion IMs are analyzed to identify the IMs that are most appropriate
for Probabilistic Seismic Demand Analysis (PSDA) of low ductility RC frames on the basis
of such characteristics as IM efficiency and sufficiency. Additionally, the uncertainty about
these demand models is assessed including hypothesis tests of the typical lognormal
distribution of demands and homoscedasticity assumptions. All the considerations are
based on the results of a PSDA performed on a case study.
Moreover, a probabilistic methodology for assessing the vulnerability of existing RC
buildings with limited ductility capacity and retrofitted by means of dissipative braces is
proposed. The methodology use local EDP in order to develop component and system
fragility curves of the bare and the retrofitted frame and allows to evaluate the safety level
reached by the frame before and after the retrofit by taking into account the probabilistic
properties of the seismic response and at the same time, employing an efficient structure
dependent IM. The proposed approach allows to highlight the possible changes in the most
significant collapse modalities before and after the retrofit and to evaluate the effectiveness
of the retrofit.
A benchmark 2-dimensional reinforced concrete frame with low ductility capacity is
considered as case study. The frame is designed for gravity-loads only and does not comply
with modern anti-seismic code requirements. It is retrofitted by introducing elasto-plastic
dissipative braces designed for different levels of their target base-shear capacity, following
a design method involving the pushover analysis of the bare frame. The obtained results
show the effectiveness of the use of component level vulnerability evaluation of low
ductility frames, and the effectiveness of the methodology in describing the changes in the
performance due to retrofit. The lack of accuracy as consequence of the use of these global
EDPs for evaluating vulnerability of retrofitted frames is posed in evidence. Finally, an
increase of the dispersion of the retrofitted frames with respect to the bare frame is shows
and this result implies the importance of considering the dispersion in the evaluation of
seismic safety level achieved after the retrofit. The proposed methodology also allows
testing the effectiveness of this simplified criterion employed for the design of braces.
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Dang, Cong-Thuat. "Méthodes de construction des courbes de fragilité sismique par simulations numériques." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2014. http://tel.archives-ouvertes.fr/tel-01023973.
Full textAbstract:
Une courbe de fragilité sismique qui présente la probabilité de défaillance d'une structure en fonction d'une intensité sismique, est un outil performant pour l'évaluation de la vulnérabilité sismique des structures en génie nucléaire et génie civil. On se concentre dans cette thèse sur l'approche par simulations numériques pour la construction des courbes de fragilité sismique. Une étude comparative des méthodes paramétriques existantes avec l'hypothèse log-normale est d'abord réalisée. Elle permet ensuite de proposer des améliorations de la méthode du maximum de vraisemblance dans le but d'atténuer l'influence de l'excitation sismique lors de son processus de construction. Une autre amélioration est l'application de la méthode de simulations par subsets pour l'évaluation de la probabilité de défaillance faible. Enfin, en utilisant la méthode de calcul de l'évolution des fonctions de densité de probabilité qui permet d'évaluer la probabilité conjointe entre la réponse structurale et les variables aléatoires du système et de l'excitation, nous proposons également une nouvelle technique non-paramétrique de construction des courbes de fragilité sismique sans utiliser l'hypothèse de la loi log-normale. La validation des améliorations et de la nouvelle technique est réalisée sur des exemples numériques.
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Suescun, Juliana Ruiz. "Courbes de fragilité pour les ponts au Québec tenant compte du sol de fondation." Mémoire, Université de Sherbrooke, 2010. http://savoirs.usherbrooke.ca/handle/11143/1576.
Full textAbstract:
Abstract : Fragility curves are a very useful tool for seismic risk assessment of bridges. A fragility curve describes the probability of a structure being damaged beyond a specific damage state for different levels of ground shaking. Since more than half of all bridges in the province of Quebec (Canada) are in service for more than 30 years and that these bridges were designed at that time without seismic provisions, generating fragility curves for these structures is more than necessary. These curves can be used to estimate damage and economic loss due to an earthquake and prioritize repairs or seismic rehabilitations of bridges. Previous studies have shown that seismic damage experienced by bridges is not only a function of the epicentral distance and the severity of an earthquake but also of the structural characteristics of the bridge and the soil type on which it is built. Current methods for generating fragility curves for bridges do not account for soil conditions. In this work, analytical fragility curves are generated for multi-span continuous concrete girder bridges, which account for 21% of all bridges in Quebec, for the different soil profile types specified in the Canadian highway bridge design code (CAN/CSA-S6-06). These curves take into account the different types of abutment and foundation specific to these bridges. The fragility curves are obtained from time-history nonlinear analyses using 120 synthetic accelerograms generated for eastern Canadian regions, and from a Monte Carlo simulation to combine the fragility curves of the different structural components of a bridge||Résumé : Les courbes de fragilité sont un outil très utile pour l’évaluation du risque sismique des ponts. Une courbe de fragilité représente la probabilité qu'une structure soit endommagée au-delà d'un état d'endommagement donné pour différents niveaux de tremblement de terre. Étant donné que plus de la moitié des ponts dans la province de Québec (Canada) ont plus de 30 années de service et que ces ponts n'ont pas été conçus à l'époque à l'aide de normes sismiques, la génération de courbes de fragilité pour ces structures est plus que nécessaire. Ces courbes peuvent servir à estimer les dommages et les pertes économiques causés par un tremblement de terre et à prioriser les réparations ou les réhabilitations sismiques des ponts. Des études antérieures ont montré que l'endommagement subi par les ponts suite à un tremblement de terre n'est pas seulement fonction de la distance de l'épicentre et de la sévérité du tremblement de terre, mais aussi des caractéristiques structurales du pont et du type de sol sur lequel il est construit. Les méthodes actuelles pour générer les courbes de fragilité des ponts ne tiennent pas compte des conditions du sol. Dans ce travail de recherche, des courbes de fragilité analytiques sont générées pour les ponts à portées multiples à poutres continues en béton armé, soit pour 21% des ponts au Québec, pour les différents types de sol spécifiés dans le Code canadien sur le calcul des ponts routiers (CAN/CSA-S6-06). Ces courbes prennent en compte les différents types de culée et de fondation spécifiques à ces ponts. Les courbes de fragilité sont obtenues à partir d'analyses temporelles non linéaires réalisées à l'aide de 120 accélérogrammes synthétiques généres pour l’est du Canada, et d'une simulation de Monte Carlo pour combiner les courbes de fragilité des différentes composantes du pont.
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Nardin, Chiara. "Seismic experimental analyses and surrogate models of multi-component systems in special-risk industrial facilities." Doctoral thesis, Università degli studi di Trento, 2022. https://hdl.handle.net/11572/362462.
Full textAbstract:
Nowadays, earthquakes are one of the most catastrophic natural events that have a significant human, socio-economic and environmental impact. Besides, based on both observations of damage following recent major/moderate seismic events and numerical/experimental studies, it clearly emerges that critical non-structural components (NSCs) that are ubiquitous to most industrial facilities are particularly and even disproportionately vulnerable to those events.
Nonetheless and despite their great importance, seismic provisions for industrial facilities and their process equipment are still based on the classical load-and-resistance factor design (LRFD) approach; a performance-based earthquake engineering (PBEE) approach should, instead, be preferred. Along this vein, in recent years, much research has been devoted to setting computational fragility frameworks for special-risk industrial components and structures.
However, within a PBEE perspective, studies have clearly remarked: i) a lack of definition of performance objectives for NSCs; ii) the need for fully comprehensive testing campaigns data on coupling effects between main structures and NSCs. In this respect, this doctorate thesis introduces a computational framework for an efficient and accurate seismic state-dependent fragility analysis; it is based on a combination of data acquired from an extensive experimental shake table test campaign on a full-scale prototype industrial steel frame structure and the most recent surrogate-based UQ forward analysis advancements. Specifically, the framework is applied to a real-world application consisting of seismic shake table tests of a representative industrial multi-storey frame structure equipped with complex process components, carried out at the EUCENTRE facility in Italy, within the European SPIF project: Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities. The results of this experimental research campaign also aspire to improve the understanding of these complex systems and improve the knowledge of FE modelling techniques. The main goals aim to reduce the huge computational burden and to assess, as well, when the importance of coupling effects between NSCs and the main structure comes into play. Insights provided by innovative monitoring systems were then deployed to develop and validate numerical and analytical models. At the same time, the adoption of Der Kiureghian's stochastic site-based ground motion model (GMM) was deemed necessary to severely excite the process equipment and supplement the scarcity of real records with a specific frequency content capable of enhancing coupling effects. Finally, to assess the seismic risk of NSCs of those special facilities, this thesis introduces state-dependent fragility curves that consider the accumulation of damage effects due to sequential seismic events. To this end, the computational burden was alleviated by adopting polynomial chaos expansion (PCE) surrogate models. More precisely, the dimensionality of a seismic input random vector has been reduced by performing the principal component analysis (PCA) on the experimental realizations. Successively, by bootstrapping on the experimental design, separate PCE coefficients have been determined, yielding a full response sample at each point. Eventually, empirical state-dependent fragility curves were derived.
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Prabel, Benoit. "MODÉLISATION AVEC LA MÉTHODE X-FEM DE LA PROPAGATION DYNAMIQUE ET DE L'ARRÊT DE FISSURE DE CLIVAGE DANS UN ACIER DE CUVE REP." Phd thesis, INSA de Lyon, 2007. http://tel.archives-ouvertes.fr/tel-00278939.
Full textAbstract:
Ce mémoire de thèse présente l'étude de la propagation et de l'arrêt d'une fissure de clivage dans un acier de cuve REP. Une bonne compréhension des phénomènes en jeu nécessite de solides données expérimentales, ainsi qu'un outil de modélisation performant. La méthode X-FEM est implantée dans Cast3m, permettant de simuler efficacement la propagation de fissure par éléments finis. Deux techniques concernant l'actualisation des fonctions de niveau, ainsi qu'une intégration non conforme sont proposées. La campagne d'essais de propagation de fissure concerne trois géométries : des éprouvettes CT, et des anneaux comprimés en mode I et mixte. On relève les vitesses de propagation. Des fractographies désignent le clivage comme responsable de la ruine. Un modèle de propagation basé sur la contrainte principale en pointe de fissure est identifié. La contrainte critique de clivage dépend de la vitesse de sollicitation. Ce modèle permet de prédire précisément par la simulation numérique, le comportement de la fissure observé expérimentalement.
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Castillejo, Luis Gladys Lissett, and Salinas Lizbeth Fiorella Espinoza. "Simulación de tsunami para la generación de mapas de inundación y daño en el distrito de Ancón." Bachelor's thesis, Universidad Ricardo Palma, 2015. http://cybertesis.urp.edu.pe/handle/urp/1267.
Full textAbstract:
El Perú es un país que se encuentra localizado en cinturón de fuego, zona donde ocurren el 90% de las actividades sísmicas del mundo, ocasionando pérdida de vidas humanas y pérdidas materiales, por lo que es necesario tomar las precauciones para salvaguardar el bienestar de la población que vive en estas zonas.
En Perú existen dos placas que se encuentran en la subsuelo del océano pacifico, la placa de nazca (oceánica) que ocupa una gran parte del océano pacifico y cuyo borde colisiona con la placa sudamericana (continental) originando un proceso de convergencia de la placa de Nazca por debajo de la Placa Sudamericana originando sismos pueden dar origen a tsunamis.
Este trabajo de investigación contempla la simulación de tsunamis de diferentes magnitudes históricas: 8.2 Mw (Lima –Callao 1940) y 8.5 Mw (Japon-2011) con las que se obtuvieron dos escenarios de tsunami de estudio para el distrito de Ancón.
Cuyo epicentro de sismo fue tomado en 11°32'7.65"S, 77°46'17.31"O a 70 km de la costa del Distrito de Ancón, del cual partimos los siguientes resultados: Tiempo de llegada de la primera ola para los dos escenarios, cálculo de la altura máxima de la ola empleando las formulas empíricas de Yamaguchi y Silgado. Obteniendo como resultado la probabilidad del daño con las curvas de fragilidad de Dichato y American Samoa esto en relación al tipo de material predominante de la zona de estudio.
Todos los resultados que se obtuvo con la plataforma S.I.G fueron representados en mapas y diagramas estadísticos.
De los cuales podemos decir que en el distrito de Ancón para los dos escenarios se obtuvieron resultados para poder planificar y mitigar los efectos que trae consigo un tsunami haciendo conocer el probable comportamiento del tsunami mostrando en los mapas cuales son las áreas que serán afectadas con los cuales se podrá tomar planes de contingencia.
Peru is a country that is located in the Ring of Fire, an area where 90% of the world's seismic activity occur, causing life's human and property losses, making it necessary to take precautions to safeguard the welfare of the people living in these areas. In Peru there are two plaques found in the subsoil of the Pacific Ocean, the Nazca plate (oceanic) that occupies a large part of the Pacific Ocean and whose edge collides with the South American plate (continental) causing a process of convergence of the Nazca plate under the South American plate, causing earthquakes that may give rise to tsunamis.
This research involves the simulation of tsunamis from different historical magnitudes: 8.2 Mw (Lima -Callao 1940) and 8.5 MW (Japan, 2011). We obtained two study tsunami scenarios for the district of Ancon.
The epicenter of the Earthquake was taken in 11°32'7.65"S, 77°46'17.31"W at 70 km from the coast district of Ancon, of these we assume the following results: Time of arrival of the first sea wave for the two scenarios, calculation of the max height of the sea wave using empirical formulas of Yamaguchi and Silgado. Obtaining as a result the likelihood of damage with the fragility's curves of Dichato and American Samoa in relation to this type of predominant material of the study area.
All the results obtained with the GIS platform , were represented in maps and statistical charts.
In the two scenarios of the district of Ancon were obtained results to plan and mitigate the effects that brings a tsunami, making known the likely behavior of the tsunami, this work shows the maps the areas that will be affected and these could have contingency plans.