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  • 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.
21

UAB “Kamesta” verslo plėtra / The activity strategy of UAB “Kamesta”

Paunksnis, Mantas 03 June 2009 (has links)
Tyrimo objektas yra UAB “Kamesta”. Darbe analizuojama įmonės gamybiniai techniniai pajėgumai, organizacinė valdymo struktūra, kokybės ir aplinkosaugos sistemų diegimas, rinkos galimybės, konkurencinė aplinka bei verslo plėtros strategija. Tyrimui naudota įvairi mokslinė literatūra, statistiniai duomenys, internetiniai šaltiniai bei UAB “Kamesta” asmeniniai dokumentai. Duomenys pateikiami ne tik teoriniu, bet ir grafiniu būdu. Darbe yra lentelių bei vaizdinės medžiagos. Atlikus literatūros analizę, pateikiami gauti tyrimo rezultatai, kuriuose atsispindi įmonės veiklos raida ir dabartis, turima technika ir pajėgumai bei valdymo struktūra. Remiantis šiais duomenimis, formuojama UAB “Kamesta” veiklos strategija. Analizuojama įmonės investicijų politika, kokybės bei aplinkosaugos sistemų diegimas. Toliau suformuojamos pagrindinės įmonės verslo kryptys, į kurias įmonė labiausiai yra orientuota. Remiantis gautais duomenimis, atliekama rinkos analizė, kurios tikslas yra nustatyti UAB “Kamesta” paslaugų poreikį visuomenėje ir pagrindinius jos užsakovus. O kur yra paklausa, ten visuomet yra ir konkurencija, todėl toliau atliekama konkurencinės aplinkos analizė, įvardijant pagrindinius įmonės konkurentus, jų tikslus, siekius bei galimybes. Išanalizavus visas įmonės grandis, visi duomenys sutraukiami į kelis pagrindinius rodiklius, kurie atspindi įmonės finansinę būklę. Kitaip tariant, atliekama įmonės finansinė analizė, kurios metu palyginami pelningų 2007 m. rezultatai su praėjusių 20... [toliau žr. visą tekstą] / An object of a research is UAB “Kamesta”. In this work industrial technical capacities, organizing management structure and environment protection systems installation, market opportunities, competitive environment and business development strategy of a company there are analysed. Various scientific literature, statistic data, internet sources and personal documents of the UAB “Kamesta” there were used for this research. The data is presented not only in theoretical method, also graphic. There are also tables and images presented in this work. When analysed the literature, the obtained results of the research are presented. The development and the present of a company, its owned technology, capacity and management structure are reflected in the results of a research. The activity strategy UAB “Kamesta” is based on this data. Company’s investments politics, quality and environment protection systems installation there are analysed. Further, the main company’s business directions into which the company is orientated are formed. Referine to the received data, the market analysis is performed. The purpose of the analysis is to establish the requirement of services and the main customers of UAB “Kamesta”. Where there is a demand, the competition also exist, therefore, the analysis of the competitive environment has been carried out by identifying the main company’s competitors, their goals, aspirations and possibilities. When analysed all the links of the company, all the data... [to full text]
22

Mudança construcional de na hora que: uma abordagem cognitivo-funcional / Constructional change of na hora que: a cognitive-functional approach

Garcia, Diego Minucelli [UNESP] 07 June 2017 (has links)
Submitted by Diego Minucelli Garcia null (diego@sjrp.unesp.br) on 2017-06-29T13:20:10Z No. of bitstreams: 1 Dissertacao_Final_Diego.pdf: 1210660 bytes, checksum: ca043423b95c9628ba83d5fd5d70563c (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-06-30T13:25:30Z (GMT) No. of bitstreams: 1 garcia_dm_me_sjrp.pdf: 1210660 bytes, checksum: ca043423b95c9628ba83d5fd5d70563c (MD5) / Made available in DSpace on 2017-06-30T13:25:30Z (GMT). No. of bitstreams: 1 garcia_dm_me_sjrp.pdf: 1210660 bytes, checksum: ca043423b95c9628ba83d5fd5d70563c (MD5) Previous issue date: 2017-06-07 / A partir de uma abordagem cognitivo-funcional, baseada principalmente em Goldberg (1995, 2006), Croft (2001), Bybee (2003, 2010), Traugott (2012) e Traugott e Trousdale (2013), investiga-se neste trabalho, em uma perspectiva sincrônica, a mudança construcional e o funcionamento da locução conjuntiva ((n)a) hora (em) que como introdutora de orações hipotáticas temporais em português. Os dados da pesquisa foram extraídos do Banco de dados Iboruna, representativo da fala da região Noroeste paulista. Para este estudo, a base teórica é o modelo da Gramática de Construções (GOLDBERG, 1995; CROFT, 2001), que reconhece que a forma básica de uma estrutura sintática é uma construção, formada por um pareamento de forma e de função, essa última entendida em termos semânticos e pragmático-discursivos (CROFT, 2001). As hipóteses que orientam as análises feitas são as de que: i) em termos semânticos e morfossintáticos, ((n)a) hora (em) que seguiria o padrão das orações temporais prototípicas, marcadas por quando; ii) no português atual, ((n)a) hora (em) que estaria em processo de mudança construcional, que se verificaria principalmente por variação, tanto formal quanto funcional, ligada à construção; e iii) as diferentes formas de ((n)a) hora (em) que (na hora em que, na hora que, a hora que, hora que) refletiriam diferentes graus de mudança construcional da locução. Os resultados demonstram que a construção de fato se encontra em processo de mudança construcional, revelado por diferentes graus de produtividade, esquematicidade e composicionalidade da forma (TRAUGOTT; TROUSDALE, 2013). A partir de comparação com dados da conjunção quando, verifica-se que ((n)a) hora (em) que apresenta as mesmas propriedades constitutivas do conectivo temporal prototípico, comportamento que sustenta sua inclusão no sistema gramatical português como conectivo introdutor de espaços mentais temporais (FAUCONNIER, 1994, 2007). No entanto, a locução conjuntiva também apresenta diferenças em relação à quando, como a maior frequência de uso para introduzir eventos pontuais e eventos em textos do tipo relato de procedimento. Esses resultados indicam que ((n)a) hora (em) que exibe um grau de especialização que justifica a preferência dos falantes pela locução conjuntiva, em vez de quando. Além disso, na análise das formas alternantes da construção, os resultados indicam comportamento distinto de hora que em relação às outras formas, o que leva a considerar que essa forma, com apagamento da preposição em e do determinante a, se encontra em um estágio mais avançado do processo de mudança construcional do que as outras formas da construção. Com base nos resultados obtidos, propõe-se uma hierarquia construcional de ((n)a) hora (em) que, que tem como macroconstrução o esquema [Ncircunstancial que], forma abstrata mais genérica cuja instância intermediária, na condição de mesoconstrução, é [(prep) (art) Ntemporal (prep) que]. / From the cognitive-functional approach, based mainly on Goldberg (1995, 2006), Croft (2001), Bybee (2003, 2010), Traugott (2012) and Traugott and Trousdale (2013), this research investigates, in a synchronic perspective, the constructional change and the functioning of conjunctive phrase ((n)a) hora (em) que as an introducer of temporal hypotaxis clauses in Portuguese. The data of the research were extracted from the Iboruna database, representative of the speech of the Northwest region of the São Paulo state. For this study, the theoretical basis is the Construction Grammar model (GOLDBERG, 1995; CROFT, 2001), which recognizes that the basic form of a syntactic structure is a construction, formed by a pairing of form and meaning, the latter understood in semantic and pragmatic-discursive terms (CROFT, 2001). The hypotheses that guide the analysis in this dissertation are: i) in semantic and morphosyntactic terms, ((n)a) hora (em) que follows the pattern of prototypical temporal sentences, marked by quando; ii) in current Portuguese, ((n)a) hora (em) que is in process of constructional change, which is verified mainly by variation related to the construction, both formal and functional ; iii) the different forms of ((n)a) hora (em) que (na hora em que, na hora que, a hora que, hora que) reflect different degrees of constructional change of the phrase. Indeed the results show that the construction is in process of constructional change, revealed by different degrees of productivity, schematicity, and compositionality (TRAUGOTT; TROUSDALE, 2013). From the comparison with the data of conjunction quando, it is verified that conjunctive phrase ((n)a) hora (em) que has the same properties of the prototypical temporal connective, a behavior that corroborates its inclusion in the Portuguese grammatical system as a connective introducer of temporal mental spaces (FAUCONNIER, 1994, 2007). However, the conjunctive phrase also presents differences in relation to quando, as high frequency of use to introduce punctual events in texts of the type of procedures report. These results indicate that the construction ((n)a) hora (em) que presents a degree of specialization that justifies the preference of the speakers for this phrase, instead of quando. Moreover, in the analysis of the forms of construction, the results indicate a different behavior of na hora que in comparison to the other forms of the phrase, which leads us to consider that this form, with omission of preposition em and the determinant a, is at a more advanced stage of the constructional change process than other forms of the construction. Based on the results, a constructional hierarchy of ((n)a) hora (em) que is proposed, having the scheme [Ncircunstancial que] as macroconstruction, the abstract form more generic whose intermediate instance, in the condition of mesoconstruction, is [(prep) (art) Ntemporal (prep) que].
23

Requisitos para a modelagem de padrões de cunhagem e construções semi-produtivas no constructicon da FrameNet Brasil com foco no fomento ao desenvolvimento de tradutores automáticos

Tavares, Tatiane Silva 28 September 2018 (has links)
Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-11-01T18:58:55Z No. of bitstreams: 1 tatianesilvatavares.pdf: 3652351 bytes, checksum: ab319a3daf577b4727647589658a6657 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-11-23T11:24:07Z (GMT) No. of bitstreams: 1 tatianesilvatavares.pdf: 3652351 bytes, checksum: ab319a3daf577b4727647589658a6657 (MD5) / Made available in DSpace on 2018-11-23T11:24:07Z (GMT). No. of bitstreams: 1 tatianesilvatavares.pdf: 3652351 bytes, checksum: ab319a3daf577b4727647589658a6657 (MD5) Previous issue date: 2018-09-28 / Esta pesquisa tem por objetivo investigar as contribuições que a FrameNet e o Constructicon podem oferecer aos sistemas de Tradução por Máquina (TM) ao revisitar a literatura sobre Gramática das Construções e Padrões de Cunhagem (KAY, 2013). A hipótese é a de que utilização da base de dados de uma FrameNet, que oferece representações computacionais das estruturas cognitivas essenciais na construção do sentido (os frames), e de um Constructicon, o qual integra a informação sobre a gramática de uma língua, podem auxiliar o processamento de línguas naturais pelo computador e, consequentemente, auxiliar os sistemas de Tradução por Máquina. O segundo recorte deste trabalho refere-se à revisão da Gramática das Construções, especialmente em relação ao tratamento de padrões de cunhagem. Segundo a abordagem de Kay (2005, 2013), deve-se considerar como construção apenas a quantidade mínima de informação que o falante precisa ter para que seja capaz de entender e produzir sentenças da língua. Nesta perspectiva, assume-se que as construções de uma língua sejam estes padrões mais gerais e produtivos, os quais licenciam as mais diversas sentenças compreensíveis pelo falante. Por isso buscamos reanalisar a estrutura de quantificação indefinida: i) mar de gente, ii) oceano de calúnias, iii) enxurrada de notícias, já investigada em dissertação de mestrado (TAVARES, 2014), a fim de que se possa discutir a validade da abordagem de Kay para a modelagem computacional do padrão de quantificação. A análise dos dados é guiada pelos pressupostos da Semântica de Frames (FILLLMORE, 1982,1985; PETRUCK, 1996) e pela metodologia da FrameNet, a qual emprega a análise semântica e sintática dos objetos de investigação, pois, para as tarefas de Processamento de Línguas Naturais, é necessário que se leve em conta as regularidades da língua para que esta seja processada computacionalmente. A conclusão da análise aponta para o fato de que a modelagem da estrutura de quantificação indefinida como uma rede de padrões de cunhagem no Constructicon da FrameNet Brasil, definidos a partir de restrições soft, pode trazer um ganho de generalidade na análise e a possibilidade de que estruturas inovadoras, cunhadas por analogia, sejam igualmente reconhecíveis pelo modelo computacional resultante, o que representa um avanço em relação aos processos tradicionalmente empregados na hibridização de sistemas de tradução por máquina. / This work aims to investigate the contributions that the FrameNet and the Constructicon could offer to Machine Translation (MT) systems by revisiting the literature about Construction Grammar and Coinage Patterns (KAY, 2013). The hypothesis is that by using the FrameNet database, which offers computational representations of essential cognitive structures formeaning construction (frames), and a Constructicon database, which integrates information about the grammar of a language, it is possible to support the natural language processing by the computer and, consequently, to assist Machine Translation systems. The second point of this work refers to the review of Construction Grammar, especially the treatment of coinage patterns. According to Kay’s approach (2005, 2013), it must be considered a construction only the minimal quantity of information that a speaker needs to be able to understand and to produce sentences of the language. From this perspective, it is assumed that constructions of a language are these more general and productive patterns, which license many comprehensible sentences by the speaker. For this reason we seek to reanalyze the indefinite quantity structure: i) mar de gente, ii) oceano de calúnias, iii) enxurrada de notícias, already investigated in a dissertation (TAVARES, 2014), in order to discuss the validity of Kay's approach to the computational modeling of the quantification pattern. The analyses is guided by Frame Semantics principles (FILLLMORE, 1982,1985; PETRUCK, 1996) and by FrameNet methodology, which applies a semantic and syntactic analyses to the objects of this research, because dealing with Natural Language Processing demands an account for the language regularities so it can be computationally processed. The conclusion of the analysis points to the fact that the modeling of the indefinite quantification structure as a network of coinage patterns in the FrameNet Brasil Constructicon, defined from soft constraints, can bring about a gain of generality in the analysis and the possibility that innovative structures, coined by analogy, are equally recognizable by the resulting computational model, which represents an advance over the processes traditionally employed in the hybridization of machine translation systems.
24

A construção verbal marcadora discursiva VLocmd: uma análise centrada no uso

Teixeira, Ana Cláudia Machado 28 March 2017 (has links)
Submitted by Josimara Dias Brumatti (bcgdigital@ndc.uff.br) on 2017-03-28T18:22:22Z No. of bitstreams: 1 Tese Ana Cláudia Machado Teixeira.pdf: 2556225 bytes, checksum: 53e2ac25dc9e37cff9bdff9380a2583c (MD5) / Approved for entry into archive by Josimara Dias Brumatti (bcgdigital@ndc.uff.br) on 2017-03-28T18:34:50Z (GMT) No. of bitstreams: 1 Tese Ana Cláudia Machado Teixeira.pdf: 2556225 bytes, checksum: 53e2ac25dc9e37cff9bdff9380a2583c (MD5) / Made available in DSpace on 2017-03-28T18:34:50Z (GMT). No. of bitstreams: 1 Tese Ana Cláudia Machado Teixeira.pdf: 2556225 bytes, checksum: 53e2ac25dc9e37cff9bdff9380a2583c (MD5) / A partir do princípio de que a língua é uma rede de construções, esta tese objetiva descrever a hierarquia construcional da Construção Verbal Marcadora Discursiva (VLocMD). Embasados na perspectiva da linguística centrada no uso, investigamos as trajetórias de mudança linguística de 11 combinações de verbo e locativo da macroconstrução VLocMD que configuram uma tipologia específica da categoria de marcadores discursivos. Realizamos buscas no site “Corpus do Português” do século XIII ao XX, descrevendo a trajetória dessas 11 combinações através de contextos fontes, atípicos, críticos e isolados, com o intuito de examinar as relações sintático-semânticas subjacentes ao seu emprego até a constituição da VLocMD. Fundamentados na investigação dos processos e dos mecanismos que atuaram na formação dessa macroconstrução, identificamos vem cá como membro exemplar dessa categoria, em constructos como “Isso é, sem dúvida, reflexo de anos de intimidade com esse destilado da cana-de-açúcar, bebida muito presente na vida dos brasileiros. Mas, vem cá, o que você sabe sobre cachaça?”. Com base nesse membro, verificamos motivações nas dimensões da forma e do sentido que promoveram a incorporação de outras microconstruções por meio de mudanças construcionais e construcionalização, quais sejam: vá lá, vamos lá, está aí, espera aí, espera lá, escuta aqui, olha aí, olha aqui, olha lá e vê lá. Essas microconstruções atuam em contextos específicos com funções particulares e se distribuem em grupos de mesoconstruções que, por sua vez, definem funções mais amplas. A fim de verificar se os usuários da língua interpretam esses marcadores como uma unidade de sentido e forma, realizamos experimentos psicolinguísticos para testar nossa hipótese. Esse tratamento psicolinguístico dos dados apontou a importância do contexto na ativação de inferências sugeridas que motivam a mudança linguística. / From the principle that the language is a network of constructions this thesis aims to describe the constructional hierarchy of the Verbal Discourse Marker Construction (VLocMD). Based upon the perspective of usage-based linguistics, we investigated the language change trajectories of 11 verb and locative combinations of the macro-construction VLocMD that make up a particular type of category of discourse markers. We conducted searches in the site “Corpus of Portuguese” from the thirteenth century to the twentieth century, describing the trajectory of these 11 combinations through contexts sources, atypical, critics and isolated in order to examine the syntactic-semantic relations underlying their employment until the constitution of VLocMD. Based on the investigation of the processes and mechanisms that worked on this macro-construction formation, we identified vem cá as the exemplary member of this category, in constructs such as “Isso é, sem dúvida, reflexo de anos de intimidade com esse destilado da cana-de-açúcar, bebida muito presente na vida dos brasileiros. Mas,vem cá, o que você sabe sobre cachaça?”. Based on this member, we found motivation in the dimensions of form and meaning that promoted the incorporation of other micro-constructions through constructional changes and constructionalization, namely: vá lá, vamos lá, está aí, espera aí, espera lá, escuta aqui, olha aí, olha aqui, olha lá e vê lá. These micro-constructions work in specific contexts with particular functions and they are distributed in groups of meso-constructions, which in turn define broader functions. In order to verify that the language users interpret these discourse markers as a unit of meaning and form, we conducted psycholinguistic experiments to test our hypothesis. This psycholinguistic treatment of the data showed the importance of the context in the activation of invented inferences that motivate the linguistic change.
25

A Constructional Canine Aggression Treatment: Using a Negative Reinforcement Shaping Procedure With Dogs in Home and Community Settings.

Snider, Kellie Sisson 12 1900 (has links)
Aggression in dogs is a significant public health concern with 7.2 mortality cases per 100 million inhabitants and approximately 4.7 million dog bites annually. Canine aggression is typically viewed as a genetic trait and treated as pathology through the use of medical or respondent behavioral procedures. In this study the effects of the differential negative reinforcement of safe, alternative behaviors to aggression using distancing as the reinforcer were evaluated. The results demonstrated that even when the aggression was in evidence throughout most of the dog's lifetime, it responded quickly to changes in reinforcement contingencies.
26

Příprava a financování stavební zakázky v rámci jejího životního cyklu z pohledu zhotovitele / Preparation and financing of construction contracts during its life cycle, from the viewpoint of a contractor

Žilinský, Lukáš January 2015 (has links)
The thesis engages in an assessment of financing the building contract from the view of a contractor. In the introduction of a theoretical part there is concisely characterized the meaning and current state of the construction market in the Czech Republic. Then there is a basic description of the characteristics of the building and construction market, followed by a description of the life cycle of construction contracts. Main attention on the theoretical part is paid to the possible ways of financing the building contract from the view of the constructor. The practical part of the thesis is divided into two examples. In the first example, an analysis of financing the building contract from the view of the constructor or construction company can be seen. Following the method of financing the business activity of the construction company is a financial analysis of its capital structure with subsequent evaluation of the results. The second example contains processing of progress financing of the building contract using a form of forfaiting, i.e. redemption of medium-term debt.
27

Assessment of ductile endurance of earthquake resisting steel members

Hyland, Clark January 2008 (has links)
This thesis provides a structural and materials engineering explanation for many of the running fractures that occurred in steel structures during the destructive Kobe and Northridge earthquakes in the mid 1990s. A method is developed that allows the ductile endurance of structural steel members subjected to cyclic plastic deformation during earthquakes to be assessed and for pre-necking running fractures to be avoided. The study commenced following the 2000 World Earthquake Conference in Auckland. The conference brought together the findings of the huge research effort, in America, Japan, Europe and New Zealand, that followed the Kobe and Northridge earthquakes. The running fractures that had occurred in steel structures represented an unpredicted failure mode that structural engineers have not known how to predict or suppress through the engineering design process. A clear fundamental understanding of the causes and how to prevent the fractures did not arise from the conference. In fact apparently conflicting results were reported. Full scale cyclic tests in New Zealand on structural assemblies had not resulted in running fractures, whereas tests in American and Japan had. Structural engineers designing earthquake resistant structures rely on constructional steel to be materially homogeneous and nominally tri-linear in behaviour. Steel is expected to behave elastically under regular in-service loading, have a reliable and flat yield stress-strain characteristic, and under overload then develop predictable levels of strain-hardening in conjunction with significant plastic elongation up to its ultimate tensile strength. Steel is expected to eventually fracture after further plastic elongation and necking. Ductile design strategies and methods utilise the plastic elongation characteristics of steel to protect structures in earthquake. Plastic deformation is considered to beneficially dissipate energy generated in the structure by a severe earthquake and also dampen the structure’s response. The occurrence of running fracture without significant cyclic plastic deformation and before section necking in steelwork, therefore undermines the basis of the ductile seismic design approach. The initial part of the thesis is devoted to bringing together the fundamental aspects of materials engineering related to fracture of constructional steel. This is intended to provide a bridge of knowledge for structural engineering practitioners and researchers not fully conversant with materials engineering aspects of fracture. Fracture behaviour in steel is a broad and complex topic that developed rapidly in the twentieth century driven by the demands of technological growth. The unexpected fracture of welded liberty ships at sea in World War 2; the need for reliable long term containment for the nuclear reactors in the 1950s and 1960s; and prevention of fatigue failures in aircraft frames since the 1950s all drove engineering research into steel fracture behaviour. There are many subtle variations in definitions in the published literature on fracture that can be confusing. Therefore an attempt has been made to clarify terminology. The term brittle fracture in particular is only used in this thesis as applying to running fracture when the general or far field tensile stresses are below the yield stress of the steel. The term pre-necking or running fracture is preferred to describe the condition more broadly which may occur prior to and also after general yielding, but before section necking. Running fracture is a manifestation of pre-necking fracture in which insufficient plastic flow is available in the assembly to absorb the energy released upon fracture. The experimental studies investigated the behaviour of constructional steel commonly used in New Zealand, at various levels of plastic strain. This started with Charpy V-Notch (CVN) testing which revealed that a significant transition temperature shift and curve shape change occurs with increasing plastic strain and the associated strain-hardening. This showed that the ability of steel to avoid pre-necking or running fracture reduces as the level of plastic strain-hardening increases. Temperature controlled Crack Tip Opening Displacement (CTOD) testing was then undertaken. The setting of testing temperatures for the CTOD tests were guided by review of the CVN test results, using published CVN to fracture toughness correlation methods. However running cleavage fractures developed in the CTOD specimens at higher than predicted temperatures of 10 oC and 20 oC. These are typical service temperatures for structures in New Zealand and so are very likely to occur at the time of an earthquake. The implication from this is that there are levels of strain-hardening and conditions of material notching constraint that can lead to pre-necking and running fracture in New Zealand fabricated steel structures, under severe earthquake loading. Care was taken in the CTOD testing to monitor and maximise the capture of data electronically using a specially developed Direct Current Potential Drop method. This allowed the test results to be analysed and considered in varying ways, leading to a consistent assessment of the CTOD, crack growth, and the specific work of fracture in each test piece. While CTOD test results have sometimes been published by structural and welding engineering researchers in the wake of Kobe and Northridge, the results were typically of little use for this study as the CTOD initiation point was generally not identified effectively. The effect of remote plastic flow in the specimens was also not adequately accounted for. The CTOD test results were often simply used to help correlate other factors observed by the researchers. Side-grooving of specimens was not reported as having been used in any of the published results reviewed. When conducting CTOD test with highly ductile constructional steels it is very difficult to get useful CTOD results if the specimens are not side-grooved, as significant necking and tunnelling will otherwise occur and limit the usefulness of the results. Work by Knott and also by McRobie and Smith was seminal in terms of identifying some critical aspects of plane strain development in CTOD tests, and the links to non-metallic particle density with respect to fracture toughness and CTOD at initiation. Some of their findings with regards to the effect of pre-strain on CTOD initiation were subsequently found to confirm the experimental findings in this study. No effective methodology for prediction of pre-necking or running fracture in a structural member or assembly when subjected to gross plastic cyclic deformation was found to exist in the literature. It was concluded however that the principles of specific work of fracture, and monotonic and cyclic fracture similitude were particularly relevant. These were therefore utilised in the development of the design method proposed in this thesis. The CTOD test results were reviewed, isolating the remote plastic flow component, to determine the critical specific work of fracture property Rc of the steels tested. A meeting with Professor Kuwamura at the University of Tokyo was providential, allowing discussion of his similitude principle, and observations in person of some of the fractured specimens developed during his full scale test series’. Running fractures with cleavage were evident in the specimens, with their tell-tale chevron markings. He had predicted running fracture problems in structures in Japan ahead of the Kobe earthquake and been largely ignored. His insights were subsequently seriously considered in Japan after the earthquake. He and his colleagues developed the principle of structural similitude that relates monotonic fracture displacement ductility to cyclic fracture displacement ductility for a particular assembly. This arose from their observation that running fractures developed from ductile crack formation at blunt notches in structures. The similitude principle has echoes of the Coffin-Manson approach to ductile crack initiated low cycle fracture. The principle of similitude has a log–log relationship as does the Manson-Coffin relationship. So where notch plasticity controls the initiation of fracture in a structural assembly it is conceptually reasonable to expect that the number of cycles to initiation of fracture from a notch will have a log–log relationship to the amplitude of the cyclic strain developed in the notch. Kuwamura found that steel assemblies with lower CVN energy had reduced cyclic fracture endurance than the same assemblies made with steel with higher CVN impact energy. However no method of predicting performance of any particular assembly could be developed from his observations. The benefit of his method primarily relates to the minimising of testing necessary to assess the fracture limited cyclic displacement ductility of a structural assembly. However it doesn’t provide a means for designing a structural assembly to achieve specific levels of ductile endurance other than clearly identifying the need to use steel with good CVN characteristics. The most significant development arising from this thesis is therefore the development of a design method to assess cyclic ductile endurance. The method utilises the specific work of fracture properties obtained from CTOD specimens of the steel in conjunction with a relatively simple fracture mechanics assessment and an elasto-plastic finite element analysis (FEA). The FEA model is used to determine the displacement ductility of the assembly at the calculated onset of pre-necking fracture. The elasto-plastic stress–strain properties of the steel in various pre-strain states required for the FEA may be derived from tensile testing. Kuwamura’s similitude principle is then used to predict cyclic plastic endurance at various constant displacement ductility amplitudes. The method is extended using Miner’s rule to allow for the effects of increasing variable amplitude cyclic plastic loading. In summary the thesis explains why pre-necking and running fractures occur in steel members subjected to cyclic plastic deformation during a severe earthquake. In addition a method for consistently assessing the ability of structural steel assemblies to achieve a specified level of ductile endurance during earthquakes is proposed. The method is verified against published results for a cyclic test of a simple steel member with a crack at mid-span. / Whole document restricted, but available by request, use the feedback form to request access.
28

Assessment of ductile endurance of earthquake resisting steel members

Hyland, Clark January 2008 (has links)
This thesis provides a structural and materials engineering explanation for many of the running fractures that occurred in steel structures during the destructive Kobe and Northridge earthquakes in the mid 1990s. A method is developed that allows the ductile endurance of structural steel members subjected to cyclic plastic deformation during earthquakes to be assessed and for pre-necking running fractures to be avoided. The study commenced following the 2000 World Earthquake Conference in Auckland. The conference brought together the findings of the huge research effort, in America, Japan, Europe and New Zealand, that followed the Kobe and Northridge earthquakes. The running fractures that had occurred in steel structures represented an unpredicted failure mode that structural engineers have not known how to predict or suppress through the engineering design process. A clear fundamental understanding of the causes and how to prevent the fractures did not arise from the conference. In fact apparently conflicting results were reported. Full scale cyclic tests in New Zealand on structural assemblies had not resulted in running fractures, whereas tests in American and Japan had. Structural engineers designing earthquake resistant structures rely on constructional steel to be materially homogeneous and nominally tri-linear in behaviour. Steel is expected to behave elastically under regular in-service loading, have a reliable and flat yield stress-strain characteristic, and under overload then develop predictable levels of strain-hardening in conjunction with significant plastic elongation up to its ultimate tensile strength. Steel is expected to eventually fracture after further plastic elongation and necking. Ductile design strategies and methods utilise the plastic elongation characteristics of steel to protect structures in earthquake. Plastic deformation is considered to beneficially dissipate energy generated in the structure by a severe earthquake and also dampen the structure’s response. The occurrence of running fracture without significant cyclic plastic deformation and before section necking in steelwork, therefore undermines the basis of the ductile seismic design approach. The initial part of the thesis is devoted to bringing together the fundamental aspects of materials engineering related to fracture of constructional steel. This is intended to provide a bridge of knowledge for structural engineering practitioners and researchers not fully conversant with materials engineering aspects of fracture. Fracture behaviour in steel is a broad and complex topic that developed rapidly in the twentieth century driven by the demands of technological growth. The unexpected fracture of welded liberty ships at sea in World War 2; the need for reliable long term containment for the nuclear reactors in the 1950s and 1960s; and prevention of fatigue failures in aircraft frames since the 1950s all drove engineering research into steel fracture behaviour. There are many subtle variations in definitions in the published literature on fracture that can be confusing. Therefore an attempt has been made to clarify terminology. The term brittle fracture in particular is only used in this thesis as applying to running fracture when the general or far field tensile stresses are below the yield stress of the steel. The term pre-necking or running fracture is preferred to describe the condition more broadly which may occur prior to and also after general yielding, but before section necking. Running fracture is a manifestation of pre-necking fracture in which insufficient plastic flow is available in the assembly to absorb the energy released upon fracture. The experimental studies investigated the behaviour of constructional steel commonly used in New Zealand, at various levels of plastic strain. This started with Charpy V-Notch (CVN) testing which revealed that a significant transition temperature shift and curve shape change occurs with increasing plastic strain and the associated strain-hardening. This showed that the ability of steel to avoid pre-necking or running fracture reduces as the level of plastic strain-hardening increases. Temperature controlled Crack Tip Opening Displacement (CTOD) testing was then undertaken. The setting of testing temperatures for the CTOD tests were guided by review of the CVN test results, using published CVN to fracture toughness correlation methods. However running cleavage fractures developed in the CTOD specimens at higher than predicted temperatures of 10 oC and 20 oC. These are typical service temperatures for structures in New Zealand and so are very likely to occur at the time of an earthquake. The implication from this is that there are levels of strain-hardening and conditions of material notching constraint that can lead to pre-necking and running fracture in New Zealand fabricated steel structures, under severe earthquake loading. Care was taken in the CTOD testing to monitor and maximise the capture of data electronically using a specially developed Direct Current Potential Drop method. This allowed the test results to be analysed and considered in varying ways, leading to a consistent assessment of the CTOD, crack growth, and the specific work of fracture in each test piece. While CTOD test results have sometimes been published by structural and welding engineering researchers in the wake of Kobe and Northridge, the results were typically of little use for this study as the CTOD initiation point was generally not identified effectively. The effect of remote plastic flow in the specimens was also not adequately accounted for. The CTOD test results were often simply used to help correlate other factors observed by the researchers. Side-grooving of specimens was not reported as having been used in any of the published results reviewed. When conducting CTOD test with highly ductile constructional steels it is very difficult to get useful CTOD results if the specimens are not side-grooved, as significant necking and tunnelling will otherwise occur and limit the usefulness of the results. Work by Knott and also by McRobie and Smith was seminal in terms of identifying some critical aspects of plane strain development in CTOD tests, and the links to non-metallic particle density with respect to fracture toughness and CTOD at initiation. Some of their findings with regards to the effect of pre-strain on CTOD initiation were subsequently found to confirm the experimental findings in this study. No effective methodology for prediction of pre-necking or running fracture in a structural member or assembly when subjected to gross plastic cyclic deformation was found to exist in the literature. It was concluded however that the principles of specific work of fracture, and monotonic and cyclic fracture similitude were particularly relevant. These were therefore utilised in the development of the design method proposed in this thesis. The CTOD test results were reviewed, isolating the remote plastic flow component, to determine the critical specific work of fracture property Rc of the steels tested. A meeting with Professor Kuwamura at the University of Tokyo was providential, allowing discussion of his similitude principle, and observations in person of some of the fractured specimens developed during his full scale test series’. Running fractures with cleavage were evident in the specimens, with their tell-tale chevron markings. He had predicted running fracture problems in structures in Japan ahead of the Kobe earthquake and been largely ignored. His insights were subsequently seriously considered in Japan after the earthquake. He and his colleagues developed the principle of structural similitude that relates monotonic fracture displacement ductility to cyclic fracture displacement ductility for a particular assembly. This arose from their observation that running fractures developed from ductile crack formation at blunt notches in structures. The similitude principle has echoes of the Coffin-Manson approach to ductile crack initiated low cycle fracture. The principle of similitude has a log–log relationship as does the Manson-Coffin relationship. So where notch plasticity controls the initiation of fracture in a structural assembly it is conceptually reasonable to expect that the number of cycles to initiation of fracture from a notch will have a log–log relationship to the amplitude of the cyclic strain developed in the notch. Kuwamura found that steel assemblies with lower CVN energy had reduced cyclic fracture endurance than the same assemblies made with steel with higher CVN impact energy. However no method of predicting performance of any particular assembly could be developed from his observations. The benefit of his method primarily relates to the minimising of testing necessary to assess the fracture limited cyclic displacement ductility of a structural assembly. However it doesn’t provide a means for designing a structural assembly to achieve specific levels of ductile endurance other than clearly identifying the need to use steel with good CVN characteristics. The most significant development arising from this thesis is therefore the development of a design method to assess cyclic ductile endurance. The method utilises the specific work of fracture properties obtained from CTOD specimens of the steel in conjunction with a relatively simple fracture mechanics assessment and an elasto-plastic finite element analysis (FEA). The FEA model is used to determine the displacement ductility of the assembly at the calculated onset of pre-necking fracture. The elasto-plastic stress–strain properties of the steel in various pre-strain states required for the FEA may be derived from tensile testing. Kuwamura’s similitude principle is then used to predict cyclic plastic endurance at various constant displacement ductility amplitudes. The method is extended using Miner’s rule to allow for the effects of increasing variable amplitude cyclic plastic loading. In summary the thesis explains why pre-necking and running fractures occur in steel members subjected to cyclic plastic deformation during a severe earthquake. In addition a method for consistently assessing the ability of structural steel assemblies to achieve a specified level of ductile endurance during earthquakes is proposed. The method is verified against published results for a cyclic test of a simple steel member with a crack at mid-span. / Whole document restricted, but available by request, use the feedback form to request access.
29

Assessment of ductile endurance of earthquake resisting steel members

Hyland, Clark January 2008 (has links)
This thesis provides a structural and materials engineering explanation for many of the running fractures that occurred in steel structures during the destructive Kobe and Northridge earthquakes in the mid 1990s. A method is developed that allows the ductile endurance of structural steel members subjected to cyclic plastic deformation during earthquakes to be assessed and for pre-necking running fractures to be avoided. The study commenced following the 2000 World Earthquake Conference in Auckland. The conference brought together the findings of the huge research effort, in America, Japan, Europe and New Zealand, that followed the Kobe and Northridge earthquakes. The running fractures that had occurred in steel structures represented an unpredicted failure mode that structural engineers have not known how to predict or suppress through the engineering design process. A clear fundamental understanding of the causes and how to prevent the fractures did not arise from the conference. In fact apparently conflicting results were reported. Full scale cyclic tests in New Zealand on structural assemblies had not resulted in running fractures, whereas tests in American and Japan had. Structural engineers designing earthquake resistant structures rely on constructional steel to be materially homogeneous and nominally tri-linear in behaviour. Steel is expected to behave elastically under regular in-service loading, have a reliable and flat yield stress-strain characteristic, and under overload then develop predictable levels of strain-hardening in conjunction with significant plastic elongation up to its ultimate tensile strength. Steel is expected to eventually fracture after further plastic elongation and necking. Ductile design strategies and methods utilise the plastic elongation characteristics of steel to protect structures in earthquake. Plastic deformation is considered to beneficially dissipate energy generated in the structure by a severe earthquake and also dampen the structure’s response. The occurrence of running fracture without significant cyclic plastic deformation and before section necking in steelwork, therefore undermines the basis of the ductile seismic design approach. The initial part of the thesis is devoted to bringing together the fundamental aspects of materials engineering related to fracture of constructional steel. This is intended to provide a bridge of knowledge for structural engineering practitioners and researchers not fully conversant with materials engineering aspects of fracture. Fracture behaviour in steel is a broad and complex topic that developed rapidly in the twentieth century driven by the demands of technological growth. The unexpected fracture of welded liberty ships at sea in World War 2; the need for reliable long term containment for the nuclear reactors in the 1950s and 1960s; and prevention of fatigue failures in aircraft frames since the 1950s all drove engineering research into steel fracture behaviour. There are many subtle variations in definitions in the published literature on fracture that can be confusing. Therefore an attempt has been made to clarify terminology. The term brittle fracture in particular is only used in this thesis as applying to running fracture when the general or far field tensile stresses are below the yield stress of the steel. The term pre-necking or running fracture is preferred to describe the condition more broadly which may occur prior to and also after general yielding, but before section necking. Running fracture is a manifestation of pre-necking fracture in which insufficient plastic flow is available in the assembly to absorb the energy released upon fracture. The experimental studies investigated the behaviour of constructional steel commonly used in New Zealand, at various levels of plastic strain. This started with Charpy V-Notch (CVN) testing which revealed that a significant transition temperature shift and curve shape change occurs with increasing plastic strain and the associated strain-hardening. This showed that the ability of steel to avoid pre-necking or running fracture reduces as the level of plastic strain-hardening increases. Temperature controlled Crack Tip Opening Displacement (CTOD) testing was then undertaken. The setting of testing temperatures for the CTOD tests were guided by review of the CVN test results, using published CVN to fracture toughness correlation methods. However running cleavage fractures developed in the CTOD specimens at higher than predicted temperatures of 10 oC and 20 oC. These are typical service temperatures for structures in New Zealand and so are very likely to occur at the time of an earthquake. The implication from this is that there are levels of strain-hardening and conditions of material notching constraint that can lead to pre-necking and running fracture in New Zealand fabricated steel structures, under severe earthquake loading. Care was taken in the CTOD testing to monitor and maximise the capture of data electronically using a specially developed Direct Current Potential Drop method. This allowed the test results to be analysed and considered in varying ways, leading to a consistent assessment of the CTOD, crack growth, and the specific work of fracture in each test piece. While CTOD test results have sometimes been published by structural and welding engineering researchers in the wake of Kobe and Northridge, the results were typically of little use for this study as the CTOD initiation point was generally not identified effectively. The effect of remote plastic flow in the specimens was also not adequately accounted for. The CTOD test results were often simply used to help correlate other factors observed by the researchers. Side-grooving of specimens was not reported as having been used in any of the published results reviewed. When conducting CTOD test with highly ductile constructional steels it is very difficult to get useful CTOD results if the specimens are not side-grooved, as significant necking and tunnelling will otherwise occur and limit the usefulness of the results. Work by Knott and also by McRobie and Smith was seminal in terms of identifying some critical aspects of plane strain development in CTOD tests, and the links to non-metallic particle density with respect to fracture toughness and CTOD at initiation. Some of their findings with regards to the effect of pre-strain on CTOD initiation were subsequently found to confirm the experimental findings in this study. No effective methodology for prediction of pre-necking or running fracture in a structural member or assembly when subjected to gross plastic cyclic deformation was found to exist in the literature. It was concluded however that the principles of specific work of fracture, and monotonic and cyclic fracture similitude were particularly relevant. These were therefore utilised in the development of the design method proposed in this thesis. The CTOD test results were reviewed, isolating the remote plastic flow component, to determine the critical specific work of fracture property Rc of the steels tested. A meeting with Professor Kuwamura at the University of Tokyo was providential, allowing discussion of his similitude principle, and observations in person of some of the fractured specimens developed during his full scale test series’. Running fractures with cleavage were evident in the specimens, with their tell-tale chevron markings. He had predicted running fracture problems in structures in Japan ahead of the Kobe earthquake and been largely ignored. His insights were subsequently seriously considered in Japan after the earthquake. He and his colleagues developed the principle of structural similitude that relates monotonic fracture displacement ductility to cyclic fracture displacement ductility for a particular assembly. This arose from their observation that running fractures developed from ductile crack formation at blunt notches in structures. The similitude principle has echoes of the Coffin-Manson approach to ductile crack initiated low cycle fracture. The principle of similitude has a log–log relationship as does the Manson-Coffin relationship. So where notch plasticity controls the initiation of fracture in a structural assembly it is conceptually reasonable to expect that the number of cycles to initiation of fracture from a notch will have a log–log relationship to the amplitude of the cyclic strain developed in the notch. Kuwamura found that steel assemblies with lower CVN energy had reduced cyclic fracture endurance than the same assemblies made with steel with higher CVN impact energy. However no method of predicting performance of any particular assembly could be developed from his observations. The benefit of his method primarily relates to the minimising of testing necessary to assess the fracture limited cyclic displacement ductility of a structural assembly. However it doesn’t provide a means for designing a structural assembly to achieve specific levels of ductile endurance other than clearly identifying the need to use steel with good CVN characteristics. The most significant development arising from this thesis is therefore the development of a design method to assess cyclic ductile endurance. The method utilises the specific work of fracture properties obtained from CTOD specimens of the steel in conjunction with a relatively simple fracture mechanics assessment and an elasto-plastic finite element analysis (FEA). The FEA model is used to determine the displacement ductility of the assembly at the calculated onset of pre-necking fracture. The elasto-plastic stress–strain properties of the steel in various pre-strain states required for the FEA may be derived from tensile testing. Kuwamura’s similitude principle is then used to predict cyclic plastic endurance at various constant displacement ductility amplitudes. The method is extended using Miner’s rule to allow for the effects of increasing variable amplitude cyclic plastic loading. In summary the thesis explains why pre-necking and running fractures occur in steel members subjected to cyclic plastic deformation during a severe earthquake. In addition a method for consistently assessing the ability of structural steel assemblies to achieve a specified level of ductile endurance during earthquakes is proposed. The method is verified against published results for a cyclic test of a simple steel member with a crack at mid-span. / Whole document restricted, but available by request, use the feedback form to request access.
30

Assessment of ductile endurance of earthquake resisting steel members

Hyland, Clark January 2008 (has links)
This thesis provides a structural and materials engineering explanation for many of the running fractures that occurred in steel structures during the destructive Kobe and Northridge earthquakes in the mid 1990s. A method is developed that allows the ductile endurance of structural steel members subjected to cyclic plastic deformation during earthquakes to be assessed and for pre-necking running fractures to be avoided. The study commenced following the 2000 World Earthquake Conference in Auckland. The conference brought together the findings of the huge research effort, in America, Japan, Europe and New Zealand, that followed the Kobe and Northridge earthquakes. The running fractures that had occurred in steel structures represented an unpredicted failure mode that structural engineers have not known how to predict or suppress through the engineering design process. A clear fundamental understanding of the causes and how to prevent the fractures did not arise from the conference. In fact apparently conflicting results were reported. Full scale cyclic tests in New Zealand on structural assemblies had not resulted in running fractures, whereas tests in American and Japan had. Structural engineers designing earthquake resistant structures rely on constructional steel to be materially homogeneous and nominally tri-linear in behaviour. Steel is expected to behave elastically under regular in-service loading, have a reliable and flat yield stress-strain characteristic, and under overload then develop predictable levels of strain-hardening in conjunction with significant plastic elongation up to its ultimate tensile strength. Steel is expected to eventually fracture after further plastic elongation and necking. Ductile design strategies and methods utilise the plastic elongation characteristics of steel to protect structures in earthquake. Plastic deformation is considered to beneficially dissipate energy generated in the structure by a severe earthquake and also dampen the structure’s response. The occurrence of running fracture without significant cyclic plastic deformation and before section necking in steelwork, therefore undermines the basis of the ductile seismic design approach. The initial part of the thesis is devoted to bringing together the fundamental aspects of materials engineering related to fracture of constructional steel. This is intended to provide a bridge of knowledge for structural engineering practitioners and researchers not fully conversant with materials engineering aspects of fracture. Fracture behaviour in steel is a broad and complex topic that developed rapidly in the twentieth century driven by the demands of technological growth. The unexpected fracture of welded liberty ships at sea in World War 2; the need for reliable long term containment for the nuclear reactors in the 1950s and 1960s; and prevention of fatigue failures in aircraft frames since the 1950s all drove engineering research into steel fracture behaviour. There are many subtle variations in definitions in the published literature on fracture that can be confusing. Therefore an attempt has been made to clarify terminology. The term brittle fracture in particular is only used in this thesis as applying to running fracture when the general or far field tensile stresses are below the yield stress of the steel. The term pre-necking or running fracture is preferred to describe the condition more broadly which may occur prior to and also after general yielding, but before section necking. Running fracture is a manifestation of pre-necking fracture in which insufficient plastic flow is available in the assembly to absorb the energy released upon fracture. The experimental studies investigated the behaviour of constructional steel commonly used in New Zealand, at various levels of plastic strain. This started with Charpy V-Notch (CVN) testing which revealed that a significant transition temperature shift and curve shape change occurs with increasing plastic strain and the associated strain-hardening. This showed that the ability of steel to avoid pre-necking or running fracture reduces as the level of plastic strain-hardening increases. Temperature controlled Crack Tip Opening Displacement (CTOD) testing was then undertaken. The setting of testing temperatures for the CTOD tests were guided by review of the CVN test results, using published CVN to fracture toughness correlation methods. However running cleavage fractures developed in the CTOD specimens at higher than predicted temperatures of 10 oC and 20 oC. These are typical service temperatures for structures in New Zealand and so are very likely to occur at the time of an earthquake. The implication from this is that there are levels of strain-hardening and conditions of material notching constraint that can lead to pre-necking and running fracture in New Zealand fabricated steel structures, under severe earthquake loading. Care was taken in the CTOD testing to monitor and maximise the capture of data electronically using a specially developed Direct Current Potential Drop method. This allowed the test results to be analysed and considered in varying ways, leading to a consistent assessment of the CTOD, crack growth, and the specific work of fracture in each test piece. While CTOD test results have sometimes been published by structural and welding engineering researchers in the wake of Kobe and Northridge, the results were typically of little use for this study as the CTOD initiation point was generally not identified effectively. The effect of remote plastic flow in the specimens was also not adequately accounted for. The CTOD test results were often simply used to help correlate other factors observed by the researchers. Side-grooving of specimens was not reported as having been used in any of the published results reviewed. When conducting CTOD test with highly ductile constructional steels it is very difficult to get useful CTOD results if the specimens are not side-grooved, as significant necking and tunnelling will otherwise occur and limit the usefulness of the results. Work by Knott and also by McRobie and Smith was seminal in terms of identifying some critical aspects of plane strain development in CTOD tests, and the links to non-metallic particle density with respect to fracture toughness and CTOD at initiation. Some of their findings with regards to the effect of pre-strain on CTOD initiation were subsequently found to confirm the experimental findings in this study. No effective methodology for prediction of pre-necking or running fracture in a structural member or assembly when subjected to gross plastic cyclic deformation was found to exist in the literature. It was concluded however that the principles of specific work of fracture, and monotonic and cyclic fracture similitude were particularly relevant. These were therefore utilised in the development of the design method proposed in this thesis. The CTOD test results were reviewed, isolating the remote plastic flow component, to determine the critical specific work of fracture property Rc of the steels tested. A meeting with Professor Kuwamura at the University of Tokyo was providential, allowing discussion of his similitude principle, and observations in person of some of the fractured specimens developed during his full scale test series’. Running fractures with cleavage were evident in the specimens, with their tell-tale chevron markings. He had predicted running fracture problems in structures in Japan ahead of the Kobe earthquake and been largely ignored. His insights were subsequently seriously considered in Japan after the earthquake. He and his colleagues developed the principle of structural similitude that relates monotonic fracture displacement ductility to cyclic fracture displacement ductility for a particular assembly. This arose from their observation that running fractures developed from ductile crack formation at blunt notches in structures. The similitude principle has echoes of the Coffin-Manson approach to ductile crack initiated low cycle fracture. The principle of similitude has a log–log relationship as does the Manson-Coffin relationship. So where notch plasticity controls the initiation of fracture in a structural assembly it is conceptually reasonable to expect that the number of cycles to initiation of fracture from a notch will have a log–log relationship to the amplitude of the cyclic strain developed in the notch. Kuwamura found that steel assemblies with lower CVN energy had reduced cyclic fracture endurance than the same assemblies made with steel with higher CVN impact energy. However no method of predicting performance of any particular assembly could be developed from his observations. The benefit of his method primarily relates to the minimising of testing necessary to assess the fracture limited cyclic displacement ductility of a structural assembly. However it doesn’t provide a means for designing a structural assembly to achieve specific levels of ductile endurance other than clearly identifying the need to use steel with good CVN characteristics. The most significant development arising from this thesis is therefore the development of a design method to assess cyclic ductile endurance. The method utilises the specific work of fracture properties obtained from CTOD specimens of the steel in conjunction with a relatively simple fracture mechanics assessment and an elasto-plastic finite element analysis (FEA). The FEA model is used to determine the displacement ductility of the assembly at the calculated onset of pre-necking fracture. The elasto-plastic stress–strain properties of the steel in various pre-strain states required for the FEA may be derived from tensile testing. Kuwamura’s similitude principle is then used to predict cyclic plastic endurance at various constant displacement ductility amplitudes. The method is extended using Miner’s rule to allow for the effects of increasing variable amplitude cyclic plastic loading. In summary the thesis explains why pre-necking and running fractures occur in steel members subjected to cyclic plastic deformation during a severe earthquake. In addition a method for consistently assessing the ability of structural steel assemblies to achieve a specified level of ductile endurance during earthquakes is proposed. The method is verified against published results for a cyclic test of a simple steel member with a crack at mid-span. / Whole document restricted, but available by request, use the feedback form to request access.

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