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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.
251

Innovative noise protection solutions for Sweden's first high speed railway

Uppenberg, Caroline, Jonsson, Emma January 2018 (has links)
This thesis investigates and design innovative concepts of noise protection solutions (NPS) for the Swedish high-speed railway (HSR) that is planned to be built between Stockholm and Gothenburg in the near future. The planned traffic will start in 2035. The concepts have been developed through a design process, starting with a research phase of existing solutions for the problem, theory about noise and absorbing materials. Following by an analysis of all researched data to narrow down the project and the interviews with the Swedish transport administration, this in order to pinpoint the requirements for the NPS. To get opinions from people who are exposed to low frequency noise, two questionnaires were conducted with a total of 80 respondents. Because of the difficulty to find the exact target group of people who are only exposed to the noise from high speed trains, the first questionnaire was open for all people who are exposed to low frequency noise (traffic noise). The second questionnaire was published at Trafikverket Facebook page, and because of their high number of followers, people who are exposed to train noise could easily be reached. From the answers and the analyzed data, a requirement specification for the NPS was created with all the requirements that the NPS needed to have according to Trafikverkets standards and from the questionnaire. These requirements were the prerequisite used in the synthesis phase. Different brainstorming methods were used to develop a large amount of ideas. A workshop with people from the society was held to keep the creativity alive. From the first synthesis phase, six ideas out of 160 ideas were chosen by a dot evaluation, and in order to narrow down the ideas even more, a matrix evaluation was used. The matrix was built from the requirement specification to verify which ideas fit most of the requirements for a new NPS. From this evaluation, two concepts were chosen to be developed further. After a validation from Trafikverket, the two concepts were further developed, this by an open brainstorming session. Via discussions and sketching, new ideas for the concepts arose. We found solutions for the problems that arose with each concept and made final decisions about the design and material. Three concepts were 3D visualized in the CAD program Rhinoceros. Final touches of the concepts were made in Keyshot. Throughout this thesis, three concepts for noise protections for the HSR have been developed and the research question “How can innovation be created by using a design process?” have been discussed and answered.
252

Utvärdering av terrester laserskanning i framställandet av en 3D-modell : Baserat på underlag från ritning och terrester laserskanning av en fackverksbro / Evaluation of terrestrial laser scanning in the creation of a 3D-model

Jansson, Tom January 2018 (has links)
De senaste åren har implementeringen av building information modeling(BIM) i anläggningsbranschen trappats upp efter att den svenska regeringen under 2015 beslutat att Trafikverket i större utsträckning ska nyttja de digitala möjligheterna med BIM. Trafikverket i form av både beställare och förvaltare av det statliga vägnätet, är en stor aktör i den svenska anläggningsbranschen och konstaterar att kravställningen mot övriga branschen är centralt för att driva utvecklingen och användandet av konceptet BIM. En sådan övergång från ett ritningsbaserat till ett objektbaserat arbetssätt kommer att påverka hela den svenska anläggningsbranschen. Målbilden är att ur ett livscykelperspektiv kunna hantera all information om anläggningen med hjälp av 3D-data. Ska de uppnå det målet krävs det i något skede att den befintliga anläggningen modelleras upp i konceptet BIM En metod som används världen över för 3D-dokumentation av komplexa objekt och miljöer är tekniken terrester laserskanning. Resultatet av en skanning är omfattande med låg mätosäkerhet, vilket lämpar sig väl med framställandet av 3D-modeller. Studien primära syfte är att utifrån resultatet från en skanning undersöka vilka skillnader det finns mellan 3D-modeller beroende på val av mätmetod. Först gjordes en nulägesanalys i form av en litteraturstudie för att kunna erhålla ett aktuellt resultat och placera studien i rätt kontext. Därefter framställdes två 3D-modeller av samma objekt, med hjälp av två olika mätmetoder som sedan jämfördes för att kunna identifiera vilka skillnader mellan modellerna. Resultatet visar att valet av mätmetod påverkade resultatet på 3D-modellen där terrester laserskanning som mätmetod kunde bidra med att förbättra kvalitén på 3D-modellen. Däremot fanns det även områden där mätmetoderna kunde komplettera varandra för ett ännu bättre resultat. / In recent years, the implementation of building information modeling (BIM) in the Swedish civil engineering industry has increased. This is due to directives from the government stating that the Swedish Transport Administration (Trafikverket), in greater occurrence, will benefit from the digital possibilities with the BIM concept. Trafikverket is the government agency responsible for the long-term planning and management of public roads, construction in the infrastructure such as tunnels and bridges, and has great influence in the Swedish civil engineering industry. They claim that the key to enhance the use and development of BIM is to raise their demands towards the rest of the industry. Transitioning from a drawing-based to an object-based approach will affect the entire industry. The idea is to be able to handle all the information in 3D-data and the BIM concept throughout the entire life cycle of the construction. To reach that ambition, the already-built constructions need to be represented as 3D-models in terms of being a part of the BIM concept. Terrestrial laser scanning is a method of measurement that is being used worldwide for 3D-documentation of complex objects and environments. The result of a scan is comprehensive with low uncertainty of measurement; therefore the method is well suited to assist in the creation of 3D-models. The primary aim of the study is to examine the differences between 3D-models, depending on the measurement method that was used to create them. An analysis of the current situation in these fields-of-study was made by a literature study to place this thesis in its proper context. Although the two 3D-models were the same exact object, they were created using two different methods of measurement. The models were compared to identify the differences between them. The study unveils that the choice of measurement method influences the results of the 3D-model, where the terrestrial laser scanning method could help to improve the quality of the final product. On the other hand, there were areas where the two methods of measurement could complement each other for even better results.
253

A Microdata Analysis Approach to Transport Infrastructure Maintenance

Svenson, Kristin January 2017 (has links)
Maintenance of transport infrastructure assets is widely advocated as the key in minimizing current and future costs of the transportation network. While effective maintenance decisions are often a result of engineering skills and practical knowledge, efficient decisions must also account for the net result over an asset's life-cycle. One essential aspect in the long term perspective of transport infrastructure maintenance is to proactively estimate maintenance needs. In dealing with immediate maintenance actions, support tools that can prioritize potential maintenance candidates are important to obtain an efficient maintenance strategy. This dissertation consists of five individual research papers presenting a microdata analysis approach to transport infrastructure maintenance. Microdata analysis is a multidisciplinary field in which large quantities of data is collected, analyzed, and interpreted to improve decision-making. Increased access to transport infrastructure data enables a deeper understanding of causal effects and a possibility to make predictions of future outcomes. The microdata analysis approach covers the complete process from data collection to actual decisions and is therefore well suited for the task of improving efficiency in transport infrastructure maintenance. Statistical modeling was the selected analysis method in this dissertation and provided solutions to the different problems presented in each of the five papers. In Paper I, a time-to-event model was used to estimate remaining road pavement lifetimes in Sweden. In Paper II, an extension of the model in Paper I assessed the impact of latent variables on road lifetimes; displaying the sections in a road network that are weaker due to e.g. subsoil conditions or undetected heavy traffic. The study in Paper III incorporated a probabilistic parametric distribution as a representation of road lifetimes into an equation for the marginal cost of road wear. Differentiated road wear marginal costs for heavy and light vehicles are an important information basis for decisions regarding vehicle miles traveled (VMT) taxation policies. In Paper IV, a distribution based clustering method was used to distinguish between road segments that are deteriorating and road segments that have a stationary road condition. Within railway networks, temporary speed restrictions are often imposed because of maintenance and must be addressed in order to keep punctuality. The study in Paper V evaluated the empirical effect on running time of speed restrictions on a Norwegian railway line using a generalized linear mixed model.
254

Kostnad-/nyttoanalys av bergtekniska förundersökningar med statistisk datavärdesanalys

Liljekvist, Markus, Andersson, Daniel January 2020 (has links)
Många infrastrukturprojekt involverar byggnation i berg där det alltid finns osäkerheter att hantera, dessa kan minskas genom att utföra fler undersökningar. Eftersom förundersökningar i berg är relativt dyra gäller det att hitta en balans där fältprogrammet är ekonomiskt försvarbart. Ett området som studerats det senaste åren är att utreda kostnadsnyttan som förundersökningarna tillför. Metoden som har utvecklats kallas datavärdesanalys och används för att kunna bedöma kostnadsnyttan av att utföra ytterligare förundersökningar innan de är utförda. Syfte med studien är att utvärdera kostnadsnyttan av ytterligare förundersökningar för en injekterings- och bergförstärkningsdesign i ett riktigt bergbyggnadsprojekt. Detta kommer att göras med en utvecklad statistisk metod av datavärdesanalysen.  Förväntade resultat från studien var: Undersöka hur insamlad data från tidigare förundersökningar i projektet kan användas för att bedöma sannolikheterna i datavärdesanalysen. Utveckla datavärdesanalysen för att vara tillämpbar i ett bergbyggnadsprojekt. Testa metoden i ett byggprojekt med riktig data och kostnader. Utvärdera om den framtagna metoden är tillämpbar i ett bergbyggnadsprojekt. I studien upprättades först två olika typdesigner för injekteringen och bergförstärkningen, baserat på en begränsad mängd data som fanns tillgänglig för en utvald sektion (fall 1). Mängden data som var tillgänglig i fall 1 är liknande som i en förstudie. Sedan upprättades två nya typdesigner för vardera område där kompletterande information från högkvalitativ data från kärnborrhål, hammarborrhål och vattenförlustmätning adderades (fall 2). Sannolikheterna i datavärdesanalysen bedömdes genom att använda en statistik metod. Den statistiska metoden baserades på en monte carlo simulering där stupningen på brottet antogs variera för bergförstärkningen och konduktiviteten antogs variera för injekteringen.  Studien påvisade goda resultat för att datavärdesanalyser skulle kunna implementeras i projekt som ett beslutsunderlag. Problematiken som kan uppstå i projekt där man har olika åsikter om hur mycket förundersökningar som behövs skulle kunna elimineras genom att använda datavärdesanalyser på den tillgängliga informationen samt nyttan av mer information. Detta är viktigt ur ett samhällsekonomiskt perspektiv. Det är dock viktigt att personen som använder verktyget förstår hur metoden är uppbyggd och dess antaganden. Gör man inte det finns det stor risk att beslut fattas på grund av felaktigheter som kan finnas i både indata och misstolkad utdata. Vidare rekommenderas att metoden utvecklas innan den används i ett riktigt projekt. Exempel på detta kan vara att göra mindre antaganden. Det kan också vara att försöka koppla datavärdesanalysen till var man har utfört undersökningen på sträckan man studerar. Man skulle även kunna inkludera fler parametrar i sin monte carlo simulering. Slutligen kan man, för att göra metoden mer användarvänlig, skapa en bättre plattform som den kan användas på. / Many infrastructure projects involve construction in rock, where there are a lot of uncertainties to deal with. These uncertainties can be reduced by performing preliminary investigations. Since preliminary investigations are expensive, it is necessary to find a balance where the field program is financially justifiable. In recent years cost-benefit analysis has been studied to investigate the benefits that preliminary investigations add. The method that has been developed is called value of information analysis and it assesses the cost-benefit of doing more investigations before they are performed.  The purpose of this report is to evaluate the benefits of additional preliminary investigations in a real project that could improve the grouting and rock support designs. The studied method is VOIA (Value of Information Analysis) based on statistical probabilities. The expected result of the study was: Investigate how collected data from preliminary investigations can be used to determine the probabilities used in the VOIA concept based on statistics. Develop a VOIA concept that is based on statistics and can be applied in a real project. Test the concept in a real project with real data and costs. Evaluate however the statistical approach was suitable to be applied in a real project. First part of the study consists of establishing two basic designs for grouting and rock support, that is based on a limited amount of information for a certain section of the project (case 1). The data available in case 1 is similar to a desk study. For the second part of the study the previous designs were updated and adjusted according to the additional information, from high quality investigations such as core drilling and water pressure test (case 2). The probabilities in the value of information analysis were evaluated using a statistical approach. The method was based on a monte carlo simulation where the dip of the plane was assumed to vary for the reinforcement design. For the grouting design the conductivity was assumed to vary.   Conclusions from this report proves that a statistical approach for the VOIA concept has great possibilities of being applied in projects as a tool before making decisions regarding preliminary investigations. The problem that often occur in projects today concerning different opinions about the amount of investigations needed, could be eliminated if a well constructed statistical model can be used that has the possibility of adjusting to the amount of available data. This would be beneficial from a socioeconomic perspective. However it's important that the user of this approach understand the purpose of every assumption and understands how to interpret the output data. Otherwise, decisions can be based on errors made by assumptions or bad input data.   Furthermore, recommendations is presented in this report regarding some areas that need to be developed before it is suitable to apply the method in a real project. One is to construct the VOIA concept based on fewer assumptions. Another is to connect the VOIA method to the geographical point of where the investigations have been made. There is also a possibility to include more parameters in the monte carlo simulation. Finally, to construct a more applicable tool in a project, a user friendly platform to conduct the analysis from is a great area to develop.
255

METHODS FOR STUDYING PUBLIC SPACES' IMPACT ON THEIR LIFE : How to understand and improve them for their purpose

Westlund, Kristin January 2018 (has links)
The great impact urbanized cities have on its people has been studied since the 1960s. This has created new methods to measure this impact. However, because of lack of knowledge on how to use these methods they are rarely used in the planning process of new spaces in practice. By concluding what each method provides to our understanding of public spaces, and how they can be further developed, we can create a more holistic and efficient planning-process regarding public spaces, while aiming for the important goal “To create cities fit for people”. In this study the focus will be on two existing methods: Space syntax and Jan Gehl’s method of observation. The motivation for these particular methods is their differences in their approach. The purpose of this study is “to get a deeper understanding of already existing urban planning methods in order to improve them for their purposes”. The purpose has been divided into three questions that will be answered: What are the differences between Space syntax and Jan Gehl’s method of observation? What can they provide in the study of public spaces’ effect on public life? If, then how can they contribute to each other in order to improve the methods separately for their purposes in the study of public spaces? To answer these questions, the objective will be to measure the impact of two public spaces on their public life by using the two methods. The results will be interpreted, compared and discussed for potential further development. Regarding what is the difference between the methods, it can be described as space syntax using the perspective of space and Jan Gehl the perspective of life. This leads to space syntax being concerned about how much the space encourages usage of it while Jan Gehl’s method of observation is focusing on the behaviour of the people using the space, for example who they are and what they do. Different representations for the methods become a result of this. When discussing what each method can provide to the study of public spaces, space syntax usefulness for comparing spaces to each other and making prognosis makes it adapted to choose an appropriate location for a new project. Jan Gehl method with its high amount of details can show the success of a space in practice.  Regarding what the methods can provide to each other in order to improve them: Space syntax is not entirely accurate to the observed flow of people, mostly derived from lack of input about important destinations. Therefore, one suggestion for improvement is to introduce important destinations as a variable.  The efficiency of space syntax can be integrated to the quality measurements of Jan Gehl’s method. By using computer programs to measure people’s behaviours, the time spending to observe and catalogue can decrease. However, surveillance has in history been used without people’s knowledge by the government and therefore it is very important for ethical reasons to get the general public’s approval before using these strategies.
256

Återanvändning av schaktmassor ur ett hållbarhetsperspektiv i tre mindre kommuner / Reuse of excavated masses from a sustainability perspectivein three small municipalities

Nadhem, Umnia, Porsbo, Elsa January 2021 (has links)
I dagsläget transporteras stora mängder schaktmassor till deponier istället för att återanvändas för ändamål i projekt. Detta är på grund av att det är svårt att avgöra vilka massor som är godtagbara för återanvändning enligt lagsstiftningen. Lagstiftningen och kraven är juridiskt komplexa och leder i många fall till missförstånd. Syftet med denna rapport är att få en inblick i hur det arbetas med återanvändningen av schaktmassor ur ett hållbarhetsperspektiv i olika kommuner samt hur lagstiftningen påverkar återanvändningen av schaktmassor. För att undersöka detta har intervjuer med tre mindre kommuner samt en litteraturstudie genomförts och bidragit till att få en djupare inblick i problematiken. Byggledningssidan upplever att lagstiftningen är komplex vilket leder till att många projektledare/ byggledare väljer att inte återanvända schaktmassor. Byggledningssidan får oftast stöd och hjälp av miljöenheterna på kommunerna när det gäller frågor som berör återanvändning av schaktmassor men även när det gäller de olika kraven som finns i miljöbalken. Miljöenheten i samtliga kommuner är mer insatta i lagstiftningen men flera av dem upplever problem med tillgång till information och kommunikation mellan olika avdelningar och projekt inom kommunerna. Samtliga respondenter anser att en tydligare lagstiftning hade möjliggjort en ökning av återanvändningen av schaktmassor. De huvudsakliga slutsatserna som rapporten presenterar är att bristen på kommunikation är en bidragande faktor till att schaktmassor inte återanvänds samt att lagstiftningen försvårar arbetet med återanvändningen av schaktmassor. En begräsning i arbetet är att enbart tre mindre kommuner har undersökts. / At present, large quantities of excavated masses are transported to landfills instead of being reused for purposes in projects. This is because it is difficult to determine which masses are acceptable for reuse under the legislation. The legislation and requirements are legally complex and, in many cases, lead to misunderstandings. The purpose of this report is to gain an insight into how the reuse of excavated masses is worked on from a sustainability perspective in different municipalities and how the legislation affects the reuse of excavated masses. To investigate this, interviews with three smaller municipalities and a literature review were conducted and contributed to gaining a deeper insight into the problem. The construction management side feels that the legislation is complex, which leads to many project managers and construction managers choosing not to reuse excavated masses. The construction management department usually receives support and help from the environmental units with regards to issues concerning the reuse of excavated masses. Additionally, they acquire assistance with regard to the various requirements contained in the Environmental Code. The environmental unit in all communities is more familiar with the legislation, but several of them have experienced problems.These include access to information, communication between different departments as well as differences within projects of the community. All respondents believe that clearer legislation would have made it possible to increase the reuse of excavated masses.The main conclusions presented by the report are, that the lack of communication is a contributing factor to the fact that, excavated masses are not reused and that the legislation complicates the work with the reuse of excavated masses. A limitation in the work is that only three smaller municipalities have been examined.
257

Undersökning av godstågens punktlighet : En fallstudie enligt DMAIC vid Sweco Rail / Investigation of freight train punctuality : A DMAIC case study at Sweco Rail

Nilsson, Camilla, Öberg, Oskar January 2020 (has links)
Punktlighet är ett viktigt mätetal inom järnvägsindustrin, men också en stor utmaning. Ett övergripande mål i Sverige är att samtliga tåg, både person- och godståg, ska ha en punktlighet på 95% vid slutdestinationen, där tåg som anländer högst fem minuter efter utsatt tid räknas som punktliga. Under 2019 var godstågens punktlighet 77,9%. Försenade godståg innebär stora kostnader i form av kvalitetsavgifter för den part som orsakat förseningen, samhällsekonomiska kostnader samt ett förlorat förtroende för järnvägen där kunder väljer andra transportslag för att garantera att varorna anländer i tid. Syftet med examensarbetet är att identifiera vilka faktorer som påverkar godstågens punktlighet samt att ta fram rekommendationer för hur punktligheten kan förbättras. För att uppfylla examensarbetets syfte delades projektet upp i två delmål som besvarades genom att tillämpa problemlösningsmetodiken DMAIC. Det första delmålet var att identifiera hur godstågens punktlighet påverkades av att avgå utanför utsatt tid. Detta undersöktes genom att jämföra hur godstågens resor förändrades då de avgått punktligt samt tidigare eller senare än planerat. Genom att visualisera hur genomsnittet av respektive resa sett ut och jämföra dessa med varandra kunde det påvisas att avgångstiden inte är den mest betydande faktorn för godstågens punktlighet. Detta för att resan såg liknande ut oavsett då tågen avgick och den totala restiden skiljde sig inte åt nämnvärt. Det framkom även att tåg som avgår punktligt får färre merförseningar än tåg som avgår utanför gränserna för punktliga tåg. Det andra delmålet var att identifiera vad som påverkar godstågens punktlighet längs sträckan. Detta undersöktes genom att studera godstågens tidsavvikelse vid samtliga trafikplatser längs sträckan samt att analysera de orsakskoder som rapporterats in för respektive tågresa. Här påvisades att tågen inte körs enligt framtagen tågplan, vilket påverkar punktligheten negativt. Några identifierade orsaker till detta är att de olika tåguppdragen har olika förutsättningar att köra samma sträcka, trots att de har samma största tillåtna hastighet. Samt att det finns tåguppdrag som systematiskt reducerar den framförda hastigheten på grund av minskad bromsverkan, vilket i sin tur beror på dåliga vagnar eller för långt/tungt tågekipage. Utöver de två delmålen identifierades även att det fanns bristande datakvalitet i den inrapportering av orsakskoder som tillämpas idag. Exempelvis saknades dryga 40 % data för att förklara varför en merförsening uppstått. Examensarbetet resulterade i tre rekommendationer för hur godstågens punktlighet kan förbättras och dessa var: Kontinuerlig dialog mellan berörda parter för att ta fram en mer tillförlitlig tågplan. Systematiska avvikelser från tågplanen ska ha en högre kvalitetsavgift vid förseningar. Förbättra analysunderlaget genom en bättre inrapportering av orsakskoder. / Punctuality is an important measurement in the railway industry, but also entails some challenges. In Sweden there is an overall goal that both passenger- and freight trains should have a 95% punctuality when they arrive at their final destination, where trains who arrive at their final destination less than five minutes after scheduled arrival counts as punctual. During 2019 the punctuality for freight trains was 77,9%. Delayed freight trains are connected to large costs for both the railway industry and for the society. The purpose of this master thesis is to identify which factors affect freight train punctuality and to find recommendations on how to improve it. To fulfill this purpose, the project was divided into two milestones that were answered by applying the problem-solving methodology DMAIC. The first milestone was to identify how punctuality was affected by freight trains departing outside of their appointed departure time. This was done by comparing how journeys differentiated when trains departed punctually as well as earlier or later than planned. By comparing these with each other it was proven that departure time is not the most affecting factor when it comes to freight train punctuality. Because each trains journey had a similar pattern regardless of when they departed and the travel time for the trains did not differ significantly. Furthermore, it was found that trains that are punctual at their time of departure have less delays during the trains entire route than trains who depart outside of the time-window for punctual departure.  The second milestone was to identify what affected the freight train punctuality during the trains entire route. This was done by investigating the time deviation for each train at every measurement point during the route and by analyzing the reasons for time deviation. It turned out that the trains did not run according to the set timetable, which affected the punctuality in a negative way. A few identified reasons for this was that different trains had different prerequisites to drive the same route, even though they are planned for the same speed. And that some trains systematically reduced their speed due to a lack of breaking capacity, as a result of the train being too long or heavy. Beyond the two milestones it was identified a lack of data quality in the reporting of reasons for time deviation. For example, about 40 % of data was missing that could have further explained why the trains where delayed.  The master thesis resulted in three recommendations for how freight train punctuality can be improved, and these were: Continuous dialogue between affected parties to make a timetable that is more reliable. Systematic deviations from the timetable should have a higher cost for causing these. Improved data quality for further analysis of why delays occur.
258

Renovering av Gamla Årstabron med injekteringsbetong / Renovation of the Old Årsta bridge using pre-placed aggregate concrete

Stolt, Jens January 2015 (has links)
Gamla Årstabron i Stockholm uppvisade efter 80 år i drift omfattande skador på de bärande betongkonstruktionerna enligt en utredning som genomfördes 2006 av dåvarande Carl Bro AB på uppdrag av dåvarande Banverket Region Öst. Det konstaterades att omfattande reparationer och förstärkningar av brons betongvalv var nödvändiga för framtida rationell drift av bron. Det beslutades efter vidare utredning att de första tre valven på Södermalm i Stockholm skulle renoveras med injekteringsbetong. Renoveringen av de tre valven på fastlandet på Södermalm var ett prov i full skala för att hitta den optimala metodiken för den fortsatta renoveringen av resterande 17 betongvalv. Det här examensarbetet syftar till att utvärdera metoden med injekteringsbetong med hänsyn till injekteringsbetongens egenskaper, material och produktionsteknik.   Bakgrunden till detta examensarbete är att det finns ett stort behov av att följa upp renoveringsmetoden med injekteringsbetong eftersom den inte har använts i någon större utsträckning i Sverige sedan slutet av 1970-talet. Utvärderingen av injekteringsbetongens egenskaper har utförts genom att analysera resultaten av de provningar som utförts på betongen. Provningen har gått till så att utborrade kärnor och tillverkade provkuber har provats för bland annat tryck- och draghållfasthet (vidhäftning). Utvärderingen av material och produktionsteknik har gjorts genom observationer på arbetsplatsen där rapportförfattaren praktiserade hos NCC under juni och augusti 2008. Utöver praktiken har jag närvarat vid och dokumenterat många av de injekteringar som gjorts under projektets första år.   Huvudsyftet med att använda injekteringsbetong var att få fram en betong som uppvisar tillräckligt hög tryckhållfasthet, en viss draghållfasthet och en fri krympning av högst 0,2 ‰. Tyvärr var inte provtagningen tillräckligt omfattande för att dra statistiskt säkerställda slutsatser gällande betongens egenskaper. Det som dock kan sägas är att provtagningen samt information från nyckelpersoner från beställaren (numera Trafikverket) tenderar att bekräfta det som konstaterats i de förstudier som gjordes innan brorenoveringen startade, nämligen att injekteringsbetongen uppvisar en klart lägre krympning än konventionellt gjuten brobetong. Vad gäller tryck- och draghållfasthet så uppfyller den färdiga betongen de krav som ställdes.   Blandning av ingående material i form av ballast och cementbruk samt de enskilda materialens egenskaper visade sig vara en kritisk punkt, vilket bekräftar det som framgår av litteraturen på området. Att kravet på renhet hos ballasten, stenmaterialet, är uppfyllt är av yttersta vikt för slutresultatet. Dessutom är det mycket viktigt att cementbruket som blandas med vatten precis innan det injekteras i den stenfyllda formen håller mycket hög kvalité och är stabilt. I vissa aspekter ställer också metoden högre krav på yrkesarbetare, platsledning och övrig produktionspersonal som pumpförare jämfört med att gjuta med konventionell betong. Förutom de enskilda gruppernas kompetens är också samordningen och logistiken på arbetsplatsen en mycket viktig faktor. Att använda metoden innebär dessutom att beställare och specialister måste ha kunskap och förståelse för att metoden ur vissa synvinklar skiljer från konventionell betong, särskild med tanke på den begränsade användningen av metoden i Sverige i modern tid.   Baserat på slutresultatet av renoveringen, de provningar som utförts samt omdömen från nyckelpersoner hos beställaren var injekteringsbetong rätt metod att använda för att renovera Gamla Årstabron. / According to an investigation conducted in 2006 by the former Carl Bro AB commissioned by the former Swedish railway authority (Banverket), the old Årsta bridge in Stockholm, Sweden, was  after 80 years in operation showing signs of extensive damage on the load-bearing concrete structures. It was pointed out that the concrete vaults of the bridge needed to be repaired and reinforced in order to keep the bridge in an operational state. After further investigation it was decided that the first three vaults on the north side of the bridge were to be renovated by using pre-placed aggregate concrete. The renovation of the three vaults on the north side served as a full-scale test to find the best possible methodology for the continued renovation of the concrete structures that consists of another seventeen concrete vaults. This thesis aims to evaluate the method of using pre-placed aggregate concrete regarding its properties and materials as well as the construction technology.   The reason for this thesis is that there is a great need to follow up the renovation method using pre-placed aggregate concrete since it hasn’t been used in any great extent in Sweden since late 1970’s.The evaluation of the concrete’s properties has been done by analyzing the results of the testing that has been performed on the concrete. Test specimens consisting of concrete cores and fabricated cubes have been tested for compressive and tensile (bond) strength. The evaluation of materials and construction technology has been done by practical observations on the work site where the author worked as an intern for the contractor NCC during June and August 2008. Apart from my internship I also attended and documented many of the grouting occasions during the first year of the project.   The main intention of using pre-placed aggregate concrete was to produce a concrete with high compressive strength, certain tensile strength and a free shrinkage of at most 0,2 ‰. The testing of the concrete was unfortunately not extensive enough to draw any unambiguous conclusions concerning the properties of the concrete. The results of the tests performed as well as information from key persons from the current Swedish traffic administration (Trafikverket) do however tend to confirm what was found during the pilot studies conducted before the renovation of the bridge started, namely that the pre-placed aggregate concrete has a much lower shrinkage than conventional concrete normally used in bridges. As for compressive and tensile strength, the pre-placed aggregate concrete meets the quality requirements.    The mix of included materials, aggregate and cement-based grout, as well as the properties of the materials themselves turned out to be critical for the result, which the literature in the field confirms. The purity of the aggregate is essential for the result. Moreover, it’s very important that the cement-based grout is of high quality and stable. When comparing with traditional concreting, the method imposes higher requirements on the workforce, management and subcontractors, in some aspects. Two other key factors, apart from the competence of each group, are the coordination and the logistics on the worksite. Using pre-placed aggregate concrete also implies that clients and specialists must have knowledge and understanding concerning the differences compared to traditional concreting, especially since the method hasn’t been used in any greater extent in Sweden the last 40 years.   Based on the result of renovation, tests conducted and reviews from key persons at the Swedish transport administration the decision to use pre-placed aggregate concrete was the right one.
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Development of a Bridge SteelEdge Beam Design : FE Modelling for a Vehicle Collision andCase Study

Ramos Sangrós, Diego January 2015 (has links)
The degradation of bridge edge beam systems in Sweden entailed the study of new alternativedesigns, which may become more optimal from a life-cycle perspective than the currenttypical solution used (concrete integrated). Subsequently, a U-shaped steel edge beamproposed by the consulting engineering group Ramböll was considered by the SwedishTransport Administration for its use in a real bridge project. This thesis follows theimplementation of this alternative in a bridge project.The goals of the thesis are to study the development of the U-shaped steel edge beam solutionin the case study, and to identify the key factors behind it. The case study consists of a roadframe bridge where a heavily damaged bridge edge beam system is going to be replaced.For the structural design of the solution, a static linear analysis of a vehicle collision has beencarried out with the help of Finite Element Modelling and current codes. The report shows themodelling of the design solution throughout different development phases in the project. Thecommercial software used has been LUSAS.As an outcome of the project, four models have been designed and analysed, two of themdeveloped by the author as proposed solutions. The factors behind the different changes in thedesign have been identified as: (1) structural resistance, (2) constructability and (3) the use ofstainless steel. Moreover, the connection between the steel edge beam and the concrete slabhas been the main critical part for the structural resistance. Finally, the current preliminarymodel at the moment this thesis is written, which was proposed in the project meetings, meetsthe requirements from a structural point of view.
260

Nonlinear FEM load bearing capacity assessment of a concrete bridge subjected to support settlements : Case of a continious slab bridge with angled supports

Hansson, Daniel January 2013 (has links)
A nonlinear finite element analysis was performed for an existing road bridge in order to see if that could show a higher load bearing capacity, as an alternative to repairing or replacing. The regular linear analysis had shown that the bridge could not take any traffic load due to the effects from large and uneven support settlements. It is a five-span reinforced concrete bridge with a continuous slab on supports made out of rows of columns. The width-to-span ratio was around 1 and the supports were angled up to about 30°, giving rise to a complex three-dimensional behaviour, which was seen and studied in the nonlinear results. Since the bending moment was the limiting factor, the nonlinear analysis focused on that. The direct result was that the load bearing capacity was 730 kN for the traffic vehicle boogie load, B, in the ultimate limit state. This was however only for the load case tested, and several more disadvantageous vehicle positions may exist. Other aspects also became limiting, as the maximum allowed vertical deflection in the serviceability limit state was reached at 457 kN. The most restraining though, was the shear capacity from the linear analysis; 78 kN, since it was not possible to simulate that type of failure with the shell elements used in the nonlinear finite element analysis. The main aim of the thesis was nonetheless reached, since the nonlinear analysis was able to show a significant increase in load bearing capacity.  A comparison was made with the settlements for the nonlinear case, to see how much influence they had on the load bearing capacity for traffic load. This was performed for both the bridge and a simple two-span beam. Both showed that there was no effect on the load bearing capacity in the ultimate limit. One thing to note was that the full settlements were applied, and with no relaxation due to creep.  Another aim of the thesis was to make comments on the practical usability of the nonlinear finite element method in load bearing capacity assessments. A linear analysis was performed before the nonlinear in order to be able to determine the load case to be used in the latter. This worked well, as the strengths of the two methods could then be utilized. Convergence problems were however encountered for the nonlinear when using the regular static solver. Due to this, the dynamic explicit calculation scheme was used instead, treating the case as quasi-static. This managed to produce enough usable results. It was concluded that the nonlinear finite element method is useable for assessment calculations, but that its strengths and weaknesses must be known in order to make it an efficient method.

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