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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

[en] A HYBRID SOLUTION USING STOCHASTIC AND NEURAL NETWORKS MODELING FOR THE CONSIDERATION OF SAFETY UNCERTAINTIES IN CONSTRUCTION PLANNING METHODS / [pt] UMA SOLUÇÃO HÍBRIDA UTILIZANDO MODELAGEM ESTOCÁSTICA E DE REDES NEURAIS PARA A CONSIDERAÇÃO DE INCERTEZAS DE SEGURANÇA EM MÉTODOS DE PLANEJAMENTO DE CONSTRUÇÃO

CRISTIANO SAAD TRAVASSOS DO CARMO 24 January 2024 (has links)
[pt] Na indústria da construção, conhecida por sua natureza dinâmica e caótica, muitas vezes há acidentes de trabalho. Os métodos de planejamento existentes que abordam incertezas, no entanto, frequentemente ignoram as variáveis de segurança, e a literatura relevante é escassa. Este estudo introduz um novo método de planejamento de obras focado na influência de ocorrências de segurança na duração do projeto, especificamente em projetos de construção de usinas de energia. A principal hipótese é que eventos de segurança durante a construção afetam significativamente a duração do projeto, levando a cronogramas deficientes quando não considerados no processo de planejamento. Utilizando a teoria de processos estocásticos, particularmente o processo de quase-nascimento e morte, o estudo explora como os estados de segurança influenciam os estados de atraso. Modelos de redes neurais complementam o modelo estocástico para previsão de séries temporais bivariadas derivadas dos estados estocásticos. Dados reais de projetos demonstram que os eventos de segurança, supondo eventos de atraso planejados, são mais do que o dobro do valor dos estados de atraso. A aplicação do modelo estocástico a um projeto real com um atraso planejado de 8 dias indica um estado de segurança mais provável de 19. Os modelos de memória de curto prazo de longo prazo superam os métodos estatísticos na previsão de séries temporais bivariadas, com uma métrica de estimação quadrática média raiz significativamente menor. A abordagem de planejamento de construção híbrida proposta mostra-se adequada para as fases de pré-construção e construção, oferecendo melhores indicadores de tomada de decisão e apoiando a gestão de segurança reativa. / [en] The construction industry, known for its dynamic and chaotic nature, often experiences work accidents. Existing planning methods addressing uncertainties, however, frequently overlook safety variables, and the relevant literature is scarce. This study introduces a novel construction planning method focused on investigating the impact of safety incidents on project duration, specifically in energy infrastructure construction projects. The main hypothesis is that safety events during construction significantly affect project duration, leading to deficient schedules when not considered in the planning process. Utilizing stochastic process theory, particularly the quasi birth and death process, the study explores how safety states influence delay states. Neural network models complement the stochastic model for forecasting bivariate time series derived from safety and delay stochastic states. Real-life project data demonstrates that safety events, assuming planned delay events, are over double the delay states value. Applying the stochastic model to a real project with a planned 8-day delay indicates a most probable safety state of 19. Long short-term memory models outperform statistical methods in bivariate time series forecasting, with a significantly smaller root mean square estimation metric. The proposed hybrid construction planning approach proves suitable for both pre-construction and construction phases, offering improved decision-making indicators and supporting reactive safety management.
22

FLERVÅNINGSHUS MED TRÄSTOMME : En undersökning av utformningsprocessen för detaljlösningar i trä

Lundberg, Albin, Forsberg, Pontus January 2019 (has links)
Multi-story wood frame construction is a highly relevant topic today because of the need to continue to develop the relatively new building technique to create a sustainable way to keep constructing new buildings. Because the use of wood as a frame material in multi-story buildings is still new, there are still issues that come with the choice to use it. One of these issues is in the detailed technical solutions that are constructed, they often have faults that may lead to problems with moisture. The purpose of this degree project is to investigate these problems and more importantly the process behind constructing them. This work is also examining what can be done to counteract or minimize the issues in the planning phases of the construction as well as look at why it is important to continue developing wood construction. There are two parts of the method used in this degree project. The first part is a literature study which brings up the attributes of wood, factors for using and not using wood, the techniques used to build multi-story buildings in wood, as well as a look into the detailed technical solutions that are used and the planning process behind them. The second part is the interview study where experts in the field are interviewed to get answers about the issues that this work brings up. The interviews provided a lot of information that is relevant for this work and the result consists of the most important answers from them. The biggest factor for continuing to develop the use of wood as a frame material, from the interviews, was about the eco-friendliness of the material. The attitude to use wood in multi-story buildings varies quite a bit depending on which part of the construction sector is asked. The developers are curious but still a bit worried, because of this they have not yet taken the next step in using it more. The entrepreneurs are still sceptical about the use in multi-story constructions and there is not enough knowledge about it for them to earn the same amounts of money as if they were to use concrete or steel. Because of that they are also worried about taking the next step towards using wood more. The consultants, like the architects and construction engineers, are more positive to the use of wood and are inclined to use it more and more. The issues that come up the most are different types of attachments of balconies and exterior corridors, parts that are installed too close to the ground and solutions where the end grain of the wood is in water. There were three main problems that came up repeatedly. The biggest one was the lack of knowledge in the planning and the production phases. The second one was about how there is often no one who looks at the bigger picture in the projects which entails mistakes that could be caught. The last issue was in the installation where the construction workers might not do it according to the construction drawings or a lack of drawings which leads to improvisation at the construction site. Recommended improvements could be a standardisation of the solutions that are proven to work for everyone to use. There is also a need for better communication which provides feedback to the designers of the solutions, that way they will know what to do better in the future. More relevant education within the topic and better coordination will also prove vital in the continued development of multistory wooden constructions.

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