• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 123
  • 13
  • 10
  • 5
  • 4
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 208
  • 208
  • 94
  • 37
  • 32
  • 31
  • 29
  • 28
  • 28
  • 28
  • 27
  • 25
  • 20
  • 19
  • 19
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Análise Preliminar de Perigos(APP) em projetos de arquitetura: aplicação e teste de viabilidade da ferramenta de análise de risco / Preliminary Hazard Analysis (PHA) applied to architecture design level: application and test of risk analysis tools

Barretto, Rubia da Eucaristia 18 March 2008 (has links)
O objetivo foi testar a viabilidade de aplicação da ferramenta da Análise Preliminar de Perigo (APP) em projeto de arquitetura. As bases conceituais foram extraídas da análise de risco de processos industriais e segurança no ambiente de trabalho. A estrutura de encaminhamento da análise foi referenciada na norma internacional ISO 6.241 (International Organization for Standardization Performance standards in building Principles for their preparation and factors to be considered), a qual orienta a avaliação de desempenho do edifício, seus elementos e instalações, quando submetidos a condições normais de exposição e uso. Os referenciais utilizados como requisitos foram: segurança ao fogo e segurança ao uso; este último, com ênfase na acessibilidade. Os critérios aplicados foram norteados pelo Decreto do Estado de São Paulo, n. 46.076, de 31 de agosto de 2001, e pela norma da ABNT NBR 9.050, 2004. A adequação da APP ao uso em projeto de arquitetura envolveu a estruturação das categorias de análise, adequação da estrutura de composição da APP, a sistematização e codificação de listas de verificações, uso do aplicativo Excel e formatação de questionários com validação dos níveis de importância por especialistas. A ferramenta foi testada em dois edifícios do campus USP/Leste. Constatou-se que o uso dos macros facilitou a priorização dos pontos de interesse no processo de tomada de decisão, tanto para o projetista (matriz de risco por meio do nível de ação), indicando as situações relevantes para a melhoria contínua do projeto, como para o gerente de projetos (significância), trazendo informações representativas para sua atuação. Nos projetos analisados as falhas recaíram sobre as especificações de materiais, consideradas para o projetista como substancial ficando a distribuição espacial versus funcionalidade com um grau de importância moderado em situações de emergência. No atual estágio de desenvolvimento da ferramenta, o analista precisa ter habilidades como: senso crítico na comparação entre o prescritivo (leis, normas e regulamentos) e o real (proposição projetual) e capacidade de reconhecer os caminhos críticos entre os vários elementos dos subsistemas que contribuem para a geração de conflitos, desvios e falhas na proposição projetual. Este estudo confirma a viabilidade da aplicação da APP em projeto de arquitetura; entretanto, há necessidade do uso de um aplicativo que integre sistemicamente um banco de dados prescritivo e gráfico, permitindo uma associação entre os subsistemas e suas interfaces com desempenho, além da facilidade de manuseio. / This MASTER thesis aims at testing the viability of the Preliminary Hazard Analysis Tool (PHA) on architecture design level. The conceptual bases come from risk analysis industrial processes and security on labor ambient. The architecture design analysis was based on international standard ISO6241 (International organization for standardization Performance standards in building Principles for their preparation and factors to be considered) which establishes the performance evaluation of buildings, their elements and facilities when they are under use and external exposure conditions. The following performance requirements were adopted: fire safety and use safety, the last one with emphasis in universal accessibility. The performance criteria were oriented by São Paulo State Law n° 46.076 august 31, 2001 and national standard ABNT NBR9.050: 2004. The adaptation of PHA for application to architecture design level implies the structure of analysis categories, structure of PHA, systematization and codification of checklists, use of Excel application, formulation of questionnaires and validation of importance levels based on declared preference technique. The PHA tool was tested on two building projects of Campus USP/ Leste of University of São Paulo. The employment of programming scripts (excel macros) has demonstrated their potential for facilitating prioritization of actions during the design process. The designer could be able to improve the technical solutions by mean of the action level pointed by risk matrix and the manager could be able to take the most suitable decision by mean of the degree of significance. The main faults detected in the analyzed projects are related to: lack and inadequacy of materials specification and poor spaces functionality. The PHA tool user is supposed to have prior abilities such as: common sense in order to compare the prescription (laws, standards) to the real situation (design) as well as has the capacity of finding the critical path between many elements of the subsystems that contribute to the generation of conflicts and failures on the project. This study confirms the viability of PHA application in architecture design level, however, it is necessary the use of an application which integrates systemically a prescriptive and graphic database, allows an association between the subsystems and their interfaces with constructive performance and is easy of utilization.
152

Assessment of Seismic Retrofit Prioritization Methodology for Oregon's Highway Bridges Based on the Vulnerability of Highway Segments

Mehary, Selamawit Tesfayesus 18 July 2018 (has links)
Geologists have indicated that the question is not if a catastrophic earthquake will occur in Oregon but when one will occur. Scientists estimate that there is close to 40 percent conditional probability that a Cascadia subduction zone earthquake of magnitude 8.0 or above will strike Oregon in the next 50 years. In addition, the majority of Oregon's bridge inventory was built prior to the current understanding of bridge response and prior to current understanding of the expected earthquake demands. In order to minimize potential bridge damage in the case of an earthquake, one approach is to retrofit seismically deficient bridges. However, often times the decision maker is faced with the difficulty of selecting only a few bridges within the inadequate ones. Hence, the issue of prioritizing upgrading naturally arises. The goal of this study is to assess and refine bridge prioritization methodology to be utilized for ranking Oregon's bridge inventory. CFRP retrofit has been experimentally and analytically evaluated to demonstrate the effectiveness of the technique and was found to be an efficient and economical option. A vulnerability assessment estimates that close to 30 percent of Oregon's highway bridge inventory will sustain moderate damage to collapse. However, retrofitting two most common bridge types in the inventory will reduce the number of damaged bridges by about 70 percent. A cost-benefit assessment that takes into consideration direct and indirect costs associated with damaged bridges and retrofitting of bridges shows that the benefit is up to three times the cost to retrofit. The same principle was applied to rank twelve highway segments for seismic retrofit considered important by Oregon Department of Transportation. One selected segment was considered to be retrofitted and vulnerability assessed. The benefit to cost ratios for each assessment was compared and the highway segments were ranked accordingly. The top five segments in the ranking happen to be located in the East-West corridor connecting I-5 to US-101.
153

Seismic Performance of Substandard Reinforced Concrete Bridge Columns under Subduction-Zone Ground Motions

Lopez Ibaceta, Alvaro Francisco 04 June 2019 (has links)
A large magnitude, long duration subduction earthquake is impending in the Pacific Northwest, which lies near the Cascadia Subduction Zone (CSZ). Great subduction zone earthquakes are the largest earthquakes in the world and are the sole source zones that can produce earthquakes greater than M8.5. Additionally, the increased duration of a CSZ earthquake may result in more structural damage than expected. Given such seismic hazard, the assessment of reinforced concrete substructures has become crucial in order to prioritize the bridges that may need to be retrofitted and to maintain the highway network operable after a major seismic event. Recent long duration subduction earthquakes occurred in Maule, Chile (Mw 8.8, 2010) and Tohoku, Japan (Mw 9.0, 2011) are a reminder of the importance of studying the effect of subduction ground motions on structural performance. For this purpose, the seismic performance of substandard circular reinforced concrete bridge columns was experimentally evaluated using shake table tests by comparing the column response from crustal and subduction ground motions. Three continuous reinforced columns and three lap-spliced columns were tested using records from 1989 Loma Prieta, 2010 Maule and 2011 Tohoku. The results of the large-scale experiments and numerical studies demonstrated that the increased duration of subduction ground motions affects the displacement capacity and can influence the failure mode of bridge columns. Furthermore, more damage was recorded under the subduction ground motions as compared to similar maximum deformations under the crustal ground motion. The larger number of plastic strain cycles imposed by subduction ground motions influence occurrence of reinforcement bar buckling at lower displacement compared to crustal ground motions. Moreover, based on the experimental and numerical results, subduction zone ground motion effects are considered to have a significant effect on the performance of bridge columns. Therefore, it is recommended to consider the effects of subduction zone earthquakes in the performance assessment of substandard bridges, or when choosing ground motions for nonlinear time-history analysis, especially in regions prone to subduction zone mega earthquakes. Finally, for substandard bridges not yet retrofitted or upgraded seismically, the following performance limit recommendation is proposed: for the damage state of collapse, which is related to the ODOT's Life Safety performance level, the maximum strain in the longitudinal reinforcement should be reduced from 0.09 (in./in.) to a value of 0.032 (in./in.) for locations where subduction zone earthquakes are expected, to take into consideration the occurrence of bar buckling.
154

New trends for conducting hazard & operability (HAZOP) studies in continuous chemical processes

Dunjó Denti, Jordi 18 February 2010 (has links)
Identifying hazards is fundamental for ensuring the safe design and operation of a system in process plants and other facilities. Several techniques are available to identify hazardous situations, all of which require their rigorous, thorough, and systematic application by a multi-disciplinary team of experts. Success rests upon first identifying and subsequently analyzing possible scenarios that can cause accidents with different degrees of severity. While hazard identification may be the most important stage for risk management, it depends on subjectivity issues (e.g., human observation, good judgment and intuition, creativity, expertise, knowledge) which introduce bias. Without a structured identification system, hazards can be overlooked, thus entailing incomplete risk-evaluations and potential loss. The present Thesis is focused on developing both managerial and technical aspects intended to standardize one of the most used techniques for hazard identification; viz. HAZard & Operability (HAZOP) study. These criteria have been carefully implemented not only to ensure that most of the hazardous scenarios will be identified, but also that US OSHA PSM Rule, EPA RMP, and Seveso Directive requirements will be accomplished. Chapter I pioneers the main research topic; from introducing the process safety concept up to the evidence of more detailed information is required from related regulations. A review of regulations (i.e., US, Europe legislation) focused on Hazard Identification has been conducted, highlighting, there is an absence of specific criteria for performing techniques intended to identify what can go wrong. Chapter II introduces the risk management system required to analyze the risk from chemical process facilities, and justifies that hazard identification stage is the Process Safety foundation. Hereafter, an overview of the key Process Hazard Analyzes (PHA) has been conducted, and the specific HAZOP weaknesses and strengths have been highlighted to establish the first steps to focus on. Chapter III establishes the scope, the purpose and the specific objectives that the research covers. It answers the following questions on the spot: why the present research is performed, which elements are included, and what has been considered for acquiring the final conclusions of the manuscript. Chapter IV gathers HAZOP-related literature from books, guidelines, standards, major journals, and conference proceedings with the purpose of classifying the research conducted over the years and finally define the HAZOP state-of-the-art. Additionally, and according to the information collected, the current HAZOP limitations have been emphasized, and thus, the research needs that should be considered for the HAZOP improvement and advance. Chapter V analyzes the data collected while preparing, organizing, executing and writing HAZOPs in five petroleum-refining processes. A statistical analysis has been performed to extract guidance and conclusions to support the established criteria to conduct effectively HAZOP studies. Chapter VI establishes the whole set of actions that have to be taken into account for ensuring a wellplanned and executed HAZOP study. Both technical and management issues are addressed, criteria supported after considering the previous chapters of the manuscript. Chapter VI itself is the result of the present research, and could be used as a guideline not only for team leaders, but also for any related party interested on performing HAZOPs in continuous chemical processes. Chapter VII states the final conclusions of the research. The interested parties should be released about the hazard identification related-gaps present in current process safety regulations; which are the key limitations of the HAZOP study, and finally, which are the criteria to cover the research needs that have been found Annex I proposes the key tools (tables, figures and checklists "ready-to use'') to be used for conducting HAZOPs in continuous chemical processes. The information layout is structured according to the proposed HAZOP Management System. This information is intended to provide concise and structured documentation to be used as a reference book when conducting HAZOPs. Annex II is intended to overview the most relevant petroleum refining processes by highlighting key factors to take into account in the point of view of process safety and hazard identification, i.e. HAZOP. In this sense, key health and safety information of specific petroleum refining units is provided as a valuable guidance during brainstorming sessions. Annex III illustrates the complete set of data collected during the field work of the present research, and also analyzed in Chapter V of the manuscript. Additionally, it depicts a statistical summary of the key variables treated during the analysis. Finally, the Nomenclature, References, and Abbreviations & Acronyms used and cited during the manuscript have been listed. Additionally, a Glossary of key terms related to the Process Safety field has been illustrated. / La present Tesis doctoral té com a objectiu estandarditzar l'aplicació d'una de les tècniques més utilitzades a la industria de procés per a la identificació de perills; l'anomenat HAZard & OPerability (HAZOP) study, específicament a processos complexes, com per exemple, unitat de refineria del petroli.El capítol I defineix el concepte de Seguretat de Processos, i progressivament analitza les diferents regulacions relacionades amb la temàtica, detallant específicament les mancances i buits d'informació que actualment hi ha presents a la primera etapa de la gestió del risc en industries de procés: la identificació de perills.El capítol II defineix el sistema de gestió del risc tecnològic que aplica a les industries de procés, i es justifica que l'etapa d'identificació de perills és el pilar de tot el sistema. Finalment, es mencionen algunes de les tècniques d'identificació més utilitzades, els anomenats Process Hazard Analysis (PHA), i es detallen les seves mancances i fortaleses, característiques que han acabat definint la temàtica específica de la Tesis. Concretament, es dóna èmfasis a la tècnica anomenada HAZard & OPerability (HAZOP) study, objecte principal de la recerca.El capítol III defineix l'abast, el propòsit i els objectius específics de la recerca. La intenció d'aquest capítol és donar resposta a les següents qüestions: el perquè de la recerca, quins elements han estat inclosos i què s'ha considerat per tal d'assolir les conclusions de la Tesis.El capítol IV descriu l'estat de l'art de la literatura relacionada amb el HAZOP. Aquesta revisió no només permet classificar les diferents línies de recerca relacionades amb el HAZOP, sinó que també permet assolir un coneixement profund de les diferents particularitats de la pròpia tècnica. El capítol finalitza amb un conjunt de mancances tant de gestió com tècniques, així com les necessitats de recerca que poden millorar l'organització i execució dels HAZOPs.El capítol V analitza la informació que ha estat recopilada durant la fase experimental de la tesis. Les dades procedeixen de la participació en cinc estudis HAZOP aplicats a la industria de refineria del petroli.En aquest sentit, el capítol V desenvolupa una anàlisi estadística d'aquestes dades per extreure'n conclusions quant a la preparació, organització i execució dels HAZOPs.El capítol VI estableix el conjunt d'accions que s'ha de tenir en compte per tal d'assegurar que un estudi HAZOP estigui ben organitzat i executat (la metodologia). Es defineix un Sistema de Gestió del HAZOP, i a partir de les seves fases, es desenvolupa una metodologia que pretén donar suport a tots aquells punts febles que han estat identificats en els capítols anteriors. Aquesta metodologia té la intenció de donar suport i guia no només als líders del HAZOP, sinó també a qualsevol part interessada en aquesta temàtica.El capítol VII descriu les conclusions de la recerca. En primera instància s'enumeren les mancances quant a la definició de criteris a seguir de diferents regulacions que apliquen a la Seguretat de Processos.Seguidament, es mencionen les limitacions de la pròpia tècnica HAZOP, i finalment, es descriuen quins són els criteris establerts per donar solució a totes aquestes febleses que han estat identificades.L'Annex I és una recopilació de diferents criteris que han estat desenvolupats al llarg de l'escrit en forma de taules i figures. Aquestes han estat ordenades cronològicament d'acord amb les diferents fases que defineixen el Sistema de Gestió HAZOP. L'annex I es pot utilitzar com a una referència concisa i pràctica, preparada i pensada per ésser utilitzada directament a camp, amb la intenció de donar suport a les parts interessades en liderar estudis HAZOP.L'annex II recopila informació relacionada amb aspectes clau de seguretat i medi ambient en diferents unitats de refineria. Aquest informació és un suport per tal de motivar el "brainstorming" dels diferents membres que conformen l'equip HAZOP.L'Annex III recopila les dades de les diferents variables que han estat considerades a la fase experimental de la recerca, juntament amb un conjunt de figures que mostren la seva estadística bàsica.
155

Experimental Investigation and Numerical Simulation of an Unreinforced Masonry Structure with Flexible Diaphragms

Yi, Tianyi 06 April 2004 (has links)
Unreinforced masonry (URM) construction, which has been widely used in the United States, presents a large threat to life safety and regional economic development because of its poor seismic resistance. In this research, the nonlinear seismic properties of URM structures were investigated via a quasi-static test of a full-scale two-story URM building and associated analytical and numerical studies. The tests of the 24ft. by 24ft. in plan 22ft. high URM building revealed that the damage was characterized by (1) the formation of large discrete cracks in the masonry walls and (2) the rocking and sliding of URM piers. Both of these results were consistent with the predictions based on individual component properties obtained in previous research. However, the tests also revealed significant global behavior phenomena, including flange effects, overturning moment effects, and the formation of different effective piers in a perforated wall. This global behavior greatly affected the response of the URM building tested. In order to understand the nonlinear behavior of the test structure, a series of analytical studies were conducted. First, at the material level, a mechanical key model was proposed to describe the failure of URM assemblages under a biaxial state of stress. Second, at the component level, an effective pier model was developed to illustrate the mixed failure modes of a URM pier and its nonlinear force-deformation relationship. Third, at the structure level, a nonlinear pushover model was built using the mechanical models at the material and component levels to describe the nonlinear properties of a URM building. This nonlinear pushover model and a three-dimensional finite element model were employed to analyze the test structure. Both gave results in good agreement with the test data. Improvements to current provisions for the evaluation of existing masonry structures were proposed.
156

Analytical Fragility Curves for Highway Bridges in Moderate Seismic Zones

Nielson, Bryant G. 23 November 2005 (has links)
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.
157

Strategies for rapid seismic hazard mitigation in sustainable infrastructure systems

Kurata, Masahiro 14 September 2009 (has links)
The goal of this study is to design and evaluate economic and rapid seismic retrofit strategies for relatively small rehabilitation projects for steel structures consistent with the tenets of sustainable design. The need to retrofit existing structures in earthquake prone regions may arise directly from the problem of aging and deteriorating conditions, recognition of the vulnerability of existing infrastructure, from updates in seismic code requirements, or changes in building performance objectives. Traditional approaches to seismic hazard mitigation have focused reducing the failure probabilities, consequences from failures, and time to recovery. Such paradigms had been established with little regard to the impact of their rehabilitation measures on the environment and disruptions to occupants. The rapid rehabilitation strategies proposed here have sustainability benefits in terms of providing a more resilient building stock for our communities as well as minimizing environmental and economical impacts and social consequences during the rehabilitation project. To achieve these goals, a unique approach to design supplemental systems using tension-only elements is proposed. In this design approach undesirable global and local buckling are eliminated. Two rapid rehabilitation strategies are presented. The first is a bracing system consisting of cables and a central energy dissipating device (CORE Damper). The second is a shear wall system with the combined use of thin steel plate and tension-only bracing. Analytical studies using both advanced and simplified models and proof-of-concept testing were carried out for the two devices. The results demonstrated stable, highly efficient performance of the devices under seismic load. Preliminary applications of the CORE damper to the retrofitting of a braced steel frame showed the ability of the system to minimize soft story failures. Both techniques can be implemented within a sustainability framework, as these interventions reduce the seismic vulnerability of infrastructure, are low cost, utilize materials and fabrication processes widely available throughout the world, can be handled by unskilled labor and carried out with minimal disruptions to the environment. The approach taken in this study can provide a road map for future development of sustainability-based rehabilitation strategies.
158

Structural diversity and decomposition functions of volcanic soils at different stages of development

Shillam, Laura-Lee January 2008 (has links)
During a volcanic eruption, the extrusion of lava onto surfaces destroys biological activity creating virgin land surfaces. Through time this new land will be subject to soil formation and colonisation under relatively similar climatic conditions and parent materials. Soils formed from volcanic deposits present a unique opportunity to study microbial community development. Soils at different developmental stages and differing in vegetation cover were selected from four locations on the slopes of Mount Etna, Sicily. Three main research objectives were determined in order to test the hypothesis that the microbial communities from soils at later stages of development would have a greater biomass, be more diverse, be more efficient at utilising carbon sources and recover from an environmental disturbance at a greater rate. A field experiment was conducted to ascertain the long term in situ catabolic abilities of the microbial communities in each soil and to establish the effects of litter mixing on decomposition rate. Litter bags containing either Genista aetnensis (Etnean Broom), Pinus nigra (Corsican Pine) or a mixture of the two were buried at each of the sites and their decomposition monitored over a 2.5 year period. PLFA diversity, community composition and function was assessed for each of the soils. The soils were also subject to a disturbance and the recovery of key community parameters was monitored over a six month period in order to establish each soil community’s resistance and resilience to disturbance. A laboratory experiment was conducted in order to investigate functional diversity and decomposition functions of each soil community using a range of simple and complex substrates. The relationship between PLFA diversity and functional diversity was also investigated. No correlation was found between soil C and N contents, microbial biomass or soil respiration and soil developmental stage and there was no detectable difference in litter bag mass loss between the soil types. No non- additive effects were noted in mixed litters. The more developed soil had a greater PLFA diversity and PLFA biomass however the more developed soil was not more resistant or resilient to disturbance. Developed soils showed greater catabolic diversity compared with less developed soils broadly correlating with PLFA diversity. Despite increased PLFA diversity and functional diversity in the more developed soils, residue decomposition in situ was unaffected. Reduced PLFA diversity and community complexity did not result in reduced function. Soils at different developmental stages had similar catabolic responses and were able to degrade simple and complex substrates to a similar degree. Microbial diversity in soil has the potential to be very high thus resulting in a high rate of functional redundancy i.e. many species within the same community which have the same functional role. It is possible that only a few key functional groups present within the soil community contribute to the main decomposition function within the soil and were able to maintain function during perturbation. Both Etna soils had similar PLFA’s present in similar concentrations and these groups in general were maintained during disturbance. This suggests that total microbial community diversity may not be as important to community function as the presence of key functional groups.
159

Ανάλυση επικινδυνότητας λόγω ηφαιστειακής τέφρας, εκτίμηση κινδύνου και διαχείριση κρίσης στο Ηφαίστειο της Σαντορίνης

Ιωάννου, Σοφία 02 April 2014 (has links)
Στην παρούσα εργασία γίνεται αρχικά μελέτη τρωτότητας και επικινδυνότητας του ηφαιστείου της Σαντορίνης με σκοπό την μελέτη και μείωση του ηφαιστειακού κινδύνου στο νησί σε περίπτωση έκρηξης. Έπειτα καταλήγει σε προτάσεις που βοηθούν στην πρόληψη και στην σωστή διαχείριση της κατάστασης σε περίπτωση έκτακτης ανάγκης. Στο πρώτο κεφάλαιο της εργασίας περιγράφεται ο ηφαιστειακός κίνδυνος και δίνονται συγκεκριμένοι ορισμοί για έννοιες που είναι απαραίτητες γύρο από αυτόν. Ακόμη γίνεται αναφορά σε παραδείγματα άλλων ηφαιστειακών εκρήξεων με μεγάλη έκλυση τέφρας που μας ενδιαφέρουν καθώς και στην πρόσφατη σεισμική δραστηριότητα της Σαντορίνης για τα έτη 2011-2012 και ακολουθεί αναφορά σχετικά με τον στόχο της εργασίας. Το δεύτερο κεφάλαιο αναφέρεται στην ηφαιστειότητα της Σαντορίνης. Δίνεται η γενική περιγραφή των ενεργών ηφαιστείων της καλδέρας (Νέα Καμένη και Κολούμπο) και αναλύεται το γεωδυναμικό πλαίσιο, η γεωλογία και η ιστορική εξέλιξη της Σαντορίνης. Ακολούθως αναφέρεται η καθημερινή παρακολούθηση του ηφαιστείου από το ΗΜΠΙΣ και από το οποίο αντλούνται συνεχώς νέες πληροφορίες σχετικά με το ηφαίστειο. Στο τρίτο κεφάλαιο γίνεται αναλυτική περιγραφή για το κλίμα της Σαντορίνης και δίνονται τα ανεμολόγια που χρησιμοποιήθηκαν στην μελέτη για τον υπολογισμό της επικινδυνότητας για κάθε μήνα ξεχωριστά. Στο τέταρτο κεφάλαιο δίνονται οι μελέτες που έχουν γίνει μέχρι σήμερα για το θέμα και αναλύονται τα 4 σενάρια μελέτης και οι λόγοι επιλογής τους. Αυτά είναι με βάση την πηγή της έκρηξης (Κολούμπο ή Νέα Καμένη) σε συνδυασμό με το είδος της έκρηξης (υπό-Πλινιακή, Πλινιακή) iii Στο πέμπτο κεφάλαιο παρουσιάζονται τα αποτελέσματα από την έκθεση πληθυσμού και τρωτότητας για την Σαντορίνη και οι υποδομές που υπάρχουν στο νησί. Στο έκτο κεφάλαιο δίνεται η ανάλυση επικινδυνότητας για διάχυση τέφρας στην ατμόσφαιρα σε περίπτωση έκρηξης του ηφαιστείου και για κάθε σενάριο ξεχωριστά. Για τη συγκεκριμένη ανάλυση χρησιμοποιήθηκε το λογισμικό πρόγραμμα Tephra2 και έπειτα σχεδιάστηκαν οι ζώνες επικινδυνότητας αναλυτικά για κάθε μήνα και συγκεντρωτικά για κάθε περίοδο (τουριστική-χειμερινή). Στο έβδομο κεφάλαιο έγινε η τελική εκτίμηση του ηφαιστειακού κινδύνου. Αυτή προέκυψε από τις προηγούμενες μελέτες (πληθυσμού, τρωτότητας και επικινδυνότητας) και δημιουργήθηκαν ζώνες για διαφορετικά επίπεδα κινδύνου. Το όγδοο κεφάλαιο αναφέρεται στη διαχείριση του κινδύνου. Αρχικά δίνονται γενικές πληροφορίες για τα μέτρα που πρέπει να ληφθούν σε περίπτωση ηφαιστειακής έκρηξης και καταλήγει με συγκεκριμένες προτάσεις για κάθε ένα από τα σενάρια που μελετήθηκαν στη παρούσα εργασία. Από τη μελέτη προκύπτει ότι θα επηρεαστεί μεγάλο μέρος του νησιού ιδιαίτερα στα νότια λόγω έκρηξης του ηφαιστείου ακόμη και αν είναι μικρού μεγέθους. Έτσι φαίνεται η σημαντικότητα δημιουργίας ενός συγκεκριμένου σχεδίου έκτακτης ανάγκης εστιασμένο στη περίπτωση της Σαντορίνης πέρα από το γενικό σχέδιο ‘’Ξενοκράτης’’, το οποίο υπάρχει στην Ελλάδα για περιπτώσεις φυσικών καταστροφών. Τέλος ως συνέχεια της εργασίας μπορεί να γίνει μελέτη του ηφαιστειακού κινδύνου με τη χρήση του προγράμματος ΒΕΤ_VH (όμως δε λαμβάνει υπόψη μετεωρολογικά δεδομένα) και να γίνει σύγκριση των τελικών αποτελεσμάτων. / Hazard analysis due to Tephra fall, risk assessment and mitigation management for Santorini volcano In this project, firstly, it is given a study for the vulnerability and hazard assessment of Santorini’s volcano, Greece, with primary aim the further study and elimination of the volcanic risk on the island, in case of an eruption. Finally, it concludes with suggestions about the appropriate mitigation and management strategies in case of an emergency situation. On the first chapter of the project it is stated the description of the volcanic risk and all the significant definitions and meanings concerning volcanic risk. In addition, there is a description of other volcanic eruptions, which ended in a huge amount of Tephra fall and of the recent seismicity during 2011-2012 in Santorini. Then, the main reason and target of the presented project are presented. The second chapter presents the volcanism of Santorini. There is a deepest description of the 2 main volcano sources of the caldera (Nea Kameni and Kolumbo), and an analysis of the geodynamics, geology and history of Santorini. Also, the Institute for the Study and Monitoring of the Santorini Volcano (I.S.M.O.SA.V.) provides Santorini with an integral monitoring system, which guarantees the timely prediction of a possible volcanic eruption and undertakes the responsibility of disproving any false statements or rumors regarding a negative state of the volcano. The climate of the island and the meteorological data, which were used for the study of the hazard assessment are analyzed on the third chapter for every month separately. There are already some studies about the hazard assessment in Santorini. These studies and the 4 new scenarios of study for this project are given on the fourth v chapter. The 4 new scenarios combine the possible eruption source (Kolumbo, Nea Kameni) with the type of the volcanic eruption (sub-Plinian, Plinian). On the fifth chapter are presented the results of the population (value) and vulnerability assessment, as well as all the infrastructures stated on the island. On the sixth chapter is given the analysis of hazard assessment for the case of Tephra diffusion in the atmosphere and for each scenario of study. For the above analysis, the software Tephra2 was used and thereafter more specific hazard zones where formed for every month of the year and for every season (touristic-winter). On the seventh chapter is given the final estimation of the volcanic hazard. This estimation is a result of the previous studies (value, vulnerability and hazard) and every zone presents a different risk level. Finally, the eighth chapter is the part of the risk management. In the beginning of the chapter are given general mitigation strategies in case of a volcanic eruption and ends in more specified suggestions for every scenario of study separately. This project shows that a big part of the caldera, mainly in the south will be affected in case of a volcano eruption even if the eruption is of a small scale. That necessitates the creation of an emergency plan specialized for the Santorini case, different from the general national emergency plan ‘’Xenokratis’’, which already exists in Greece for possible natural disasters. For future study, it can be carried out a study of the volcanic risk with the use of the BETH_VH software (does not includes meteorological data) and to compare the final results of the two studies.
160

Seismic risk assessment of the transportation network of Charleston, SC

Nilsson, Emily Michelle 01 April 2008 (has links)
The functionality of the transportation network following an earthquake event is critical for post-earthquake response and long-term recovery. The likely performance of a transportation network can be evaluated through a detailed seismic risk assessment. This paper presents an assessment of the seismic risk to the transportation network in the City of Charleston and the surrounding counties to support emergency response and the development of mitigation strategies and emergency planning efforts (such as lifeline selections). This study includes an inventory analysis of the 375 bridges in the Charleston area, and convolution of the seismic hazard with fragility curves analytically derived for classes of bridges common to this part of the country, damage-functionality relationships, and replacement cost estimates using relevant region-specific data. Using state-of-the-art tools, the distribution of potential bridge damage and functionality is evaluated for several scenario events, in order to aid in the identification of emergency routes and assess areas for investment in retrofit. Additionally, a sensitivity study is conducted to determine the criticality of a few of the different input models. Initial estimates of economic losses are assessed and preliminary recommendations for prioritizing retrofit are presented.

Page generated in 0.0805 seconds