Rapporten innehåller inledningsvis en faktadel med allmän information kring temperatursprickor i betong. Här presenteras bl a uppkomsten av fenomenet, vilka typer av sprickor som förekommer och vad ett tvång är. Tanken är att ge läsaren tillräcklig kunskap för att kunna förstå sig på de övriga delarna i rapporten. Resultatet och det huvudsakliga arbetet redovisas i form av tabeller med tillhörande illustrationer där det går att utläsa vilken sprickrisk som förekommer vid flera specifika fall och vilken åtgärd som bör vidtas för att eliminera sprickrisken. Som konstruktör kan du med din egen indata, dvs. dimensioner och temperaturer, följa tabellen och finna resultatet för ditt specifika fall. De konstruktionstyper som presenteras är bottenplatta, stödmur och plattrambro. En tillhörande databas i elektronisk form finns tillgänglig som en bilaga där varje beräknat fall är sparat. Filerna är enkla att modifiera för att göra det möjligt att genomföra ytterliggare beräkningar i de fall tabellerna är otillräckliga. Rapporten innehåller även ett avsnitt med förutsättningar till tabellerna där det går att utläsa arbetsgången och vilka parametrar som har använts. / The initial part of the report contains general information about thermal cracks. This section describes the origin to the cracks, what type of cracks that occurs and the force causing the problem. The major reason with this chapter is to give the reader enough knowledge to understand the rest of the report. The result and the main work are presented in tables with belonging illustrations. Each table contains the risk of cracking that occurs in several specific concrete structures and how to eliminate the risk. The report covers the following three types of structures: baseplate, retaining wall and integral bridge. The constructor can with his/her own dimensions and temperatures simply use the table to find the risk of cracking. A database including all the calculated files for each specific case is attached to the report. The files can easily be modified by the user in case the information in the tables is insufficient. All the precise circumstances and priority in the project are presented in the chapter “Förutsättningar och arbetsgång”.

Pavement crack detection is an important procedure in road maintenanceand traffic safety. Traditionally, the road inventory was performed by field inspection, now it is replaced by the evaluation of mobile mapping system images. The acquired images are still a significant source of temporal condition of thepavement surface. The automatisation of crack detection is highly necessarybecause it could decrease workload, and therefore, maintenance costs. Two methods for automatic crack detection from mobile mapping imageswere tested: step by step pixel based image intensity analysis, and deep learning. The objective of this thesis is to develop and test the workflow for the streetview image crack detection and reduce image database by detecting no-cracksurfaces. To examine the performance of the methods, their classification precisionwas compared. The best-acquired precision with the trained deep learningmodel was 98% that is 3% better than with the other method and it suggeststhat the deep learning is the most appropriate for the application. Furthermore, there is a need for faster and more precise detection methods, and deep learningholds promise for the further implementation. However, future studies areneeded and they should focus on full-scale image crack detection, disturbingobject elimination and crack severity classification.

Visualization is used for stainless steel container wall and lid cross section characterization. Two specific types of containers are examined: 3013 and SAVY. The container wall examined is from a sample of the inner container of a 3013 container. The inner lid cross section examined is from a SAVY container. Laser confocal microscope data and photographic data are used to determine features of the surfaces. The surface features are then characterized by various feature statistics, such as, maximum depth, area, eccentricity, and others. The purpose of this pilot study is to demonstrate the effectiveness of using the methodology to detect potential corrosion events on the inner container surfaces. The features are used to quantify these corrosion events. An automatic image analysis system uses this methodology to classify images for possible further human analysis by flagging possible corrosion events. A manual image analysis methodology is used to determine the amount of MnS on the SAVY container lid cross section. Visualization is an integral component of the analysis methodology.

No description available.

La reproduction expérimentale de transitoires thermiques accidentels de type Accident par Perte de Réfrigérant Primaire (APRP) en laboratoire a permis d’observer la fragmentation du combustible fortement irradié lorsque la gaine se déforme sous l’augmentation de la température. Ces fragments de petites tailles peuvent se relocaliser dans le ballon voire être éjectés hors du crayon cas de rupture de gaine. La zone High Burnup Structure (HBS) des combustibles fortement irradiés est la plus susceptible de se fragmenter et d’être relocalisée par sa position en périphérie de pastille. Pour expliquer ce phénomène, l’hypothèse retenue est que le transitoire provoque une surpression dans les bulles HBS ce qui mène à la décohésion des joints de grains et à la fragmentation. Cette thèse a pour but de développer un critère de fissuration mécanique du combustible pour mieux comprendre le comportement des bulles HBS lors des conditions thermiques APRP. Ce travail se base sur une méthode une méthode micromécanique en trois étapes : i) la représentation qui permet de caractériser la microstructure de la zone HBS (leurs dimensions, leur fraction volumique, et la pression interne). Deux sources d’informations seront utilisées : les observations expérimentales provenant de disques ou de pastilles de combustible irradiés à fort taux de combustion et d’outils numériques(avec Alcyone-Caracas [JSB+14]) / Under Loss Of Coolant Accident(LOCA) transients conditions, the high irradiated fuel is fragmented in small sizes fragments who can be relocated in the balloon, or being ejected out of the fuel rod if the latter burst. This work focuses on the pellet rim, where bubbles density increases owing to a higher irradiation level. Usually the hypothesis used to explain fuel fragmentation during transient is grain cleavage induced by over pressurized fission gas bubbles, located at the grain boundary. The aim of this study is to define a macroscopic fragmentation model based on a micro mechanical approach to have a better understanding of the fuel mechanical behaviour at lower scale : size and volume fraction of fragments. This PhD introduces a stepwise micromechanical method based on three steps : i) firstly, we detail how to model the HBS microstructure including pressurized porosities, based on experimental or numerical data and define a representative volume element (RVE)

Very often defects are present in rolled products. For wire rods, defects are very deleterious since the wire rods are generally used directly in various applications. For this reason, the market nowadays requires wire rods to be completely defect-free. Any wire with defects must be rejected as scrap which is very costly for the production mill. Thus, it is very important to study the formation and evolution of defects during wire rod rolling in order to better understand and minimize the problem, at the same time improving quality of the wire rods and reducing production costs. The present work is focused on the evolution of artificial defects during rolling. Longitudinal surface defects are studied during shape rolling of an AISI M2 high speed steel and a longitudinal central inner defect is studied in an AISI 304L austenitic stainless steel during ultra-high-speed wire rod rolling. Experimental studies are carried out by rolling short rods prepared with arteficial defects. The evolution of the defects is characterised and compared to numerical analyses. The comparison shows that surface defects generally reduce quicker in the experiments than predicted by the simulations whereas a good agreement is generally obtained for the central defect. / QC 20101105

Parkeringsanläggningar utsätts ständigt av belastningar från körande fordon och kloridangrepp under vinterperioden. Påföljden av det blir kostsamma skador på betongkonstruktionen, främst vid uppkomna sprickor. Kloridinträngning medför att armeringsjärnen korroderar och försvagar underliggande betongkonstruktionen. Ersättning av de korroderade armeringsjärnen samt betonglagningar är kostsamt för Stockholm Parkering. Lösningen är att förbehandla den oskyddade betongen och applicera en ytbeläggning ovanför. De vanligaste som finns i Sverige är cementbaserade, bitumenbaserade och härdplastbaserade ytbeläggningar. Det finns inga direktiv för val när det gäller ytbeläggningar. Eftersom alla ytbeläggningar har olika egenskaper är det för- och nackdelar som beställaren ska värdera beroende på parkeringshusets förutsättningar som utformningen, trafikbelastningen och om det är grundplattan eller mellanbjälklaget som ytbeläggningen appliceras på. Förutom materialet är utförandet också viktigt. En väl utförd förbehandling av betongunderlaget och noggrann utläggning av ytbeläggningen minskar risken för uppkomst av skador i framtiden och därmed reparationskostnaderna. Syftet med examensarbetet är att undersöka olika ytbeläggningar som har varit i drift 5 till 10 år för att sedan identifiera och kartlägga skador som har uppkommit på dem. I denna rapport har fem parkeringsanläggningar valts ut som fallstudier för att undersöka de vanligaste ytbeläggningarna som används idag i Stockholm Parkerings parkeringsanläggningar. Utifrån litteraturstudier, intervjuer med olika parter i respektive projekt, observationer som utfördes under studiebesöken och jämförelse mellan fallstudier dras slutsatser för att hitta den hållbaraste ytbeläggningen. Slutligen skapas en lathund för att förenkla valet av ytbeläggningar för parkeringsanläggningar med olika förutsättningar. / Parking facilities are constantly exposed to traffic loads from driving vehicles and chloride attacks during the winter period. The consequence of this is costly damage to the concrete structure, especially in the event of cracks. Chloride penetration causes the reinforcement bars to corrode and weaken the underlying concrete structure. Replacement of the corroded reinforcement bars and concrete repairs are costly for Stockholm Parking. The solution is to pretreat the unprotected concrete and apply a coating above it. The most common coatings found in Sweden are cement-based, bitumen-based and thermoset-based coatings. There is no clear choice when it comes to coatings since they all have different properties. The advantages and disadvantages of different coatings that the customer must value depend on such conditions of the parking garage as the shaping, the traffic load and whether it is the base plate or the intermediate floor. Besides the material, the execution is also important. A well done pretreatment of the concrete substrate and meticulous laying of the coating reduces the possibility of the occurrence of damage in the future and thereby the repair costs. The purpose of the thesis project was investigation of various coatings systems that have been in operation for 5 to 10 years and identification and mapping damages that occur to them. In this report, five parking facilities have been selected as case studies to investigate the most common coatings used today in Stockholm Parkering parking facilities. Based on literature studies, interviews with various parties in each project, observations made on study visits and comparison between case studies conclusions were drawn about the most sustainable surface coating systems. Finally, a guidance is created to simplify the choice of coating systems for parking facilities with different conditions.

Järnvägsbron vid Årstaberg kommer när den är klar att mäta 1,4 km, här passerar över 550 tåg per dygn. Bron är en del av projektet Citybanan och kommer att fungera som en spårväxel som styr fjärr-, regional- och godståg till den gamla östra Årstabron. Pendeltågen kommer då färdas på bron över Årstaviken och in i den nya järnvägstunneln vid Södra station. Entreprenaden gick från början till danska företaget Pihl och Son som efter en del problem gick i konkurs, underentreprenören Züblin fick då ta över projektet. Med en ny platsledning gjordes en hel del förändringar på arbetsgången och arbetsmomenten. Från 4 veckor per sektion, där en sektion mäter ca 30 meter lyckades Züblin tillslut effektivisera till 2 veckor. Det speciella med detta projekt är den formvagn som används, den så kallade MSS:en (Moving Scaffolding System) som är relativt ovanlig i Sverige. Författarnas uppgift var att undersöka och utreda för ytterligare effektiviseringar samt redogöra för de effektiviseringar som redan gjorts av Züblin. För att ta reda på hur arbetsgången går till har en sektion av överbyggnaden följts under byggprocessen. Författarna har tagit del av tekniska detaljer som temperatursprickor, armering, spännarmering, betongkvalité och inte minst själva formvagnen. För att få en uppfattning granskades dokument och handlingar om projektet parallellt med intervjuer med inblandade och sakkunniga. Eftersom många effektiviseringsåtgärder var genomförda när författarna påbörjade examensarbetet hos Züblin lämnades inte mycket utrymme för effektiviseringar av tekniska åtgärder. Effektiviseringar som författarna har kommit fram till gäller främst arbetsmetoder och material där mer prefabricering på armering och formning över brostöd, användning av rullarmering och självkompakterande betong. Med tanke på att inga tester och provningar har utförts är detta spekulationer som tagits i samråd med inblandade nyckelpersoner med stor erfarenhet inom sina respektive områden. / The railway bridge at Årstaberg will measure 1,4 km when finished, over 550 trains passes by every 24 hours. The bridge is a part of the project Citybanan and will serve as a railway gear that directs the long-distance, regional- and cargo trains to the old Årstabron. The commuter trains will then travel on the bridge over Årstaviken and into the new railway tunnel at Södra Station. The first contractor was the Danish company Phil & Son, who after some struggles and problems went bankrupt. The subcontractor Züblin then took over the project. With the new site management, whole new changes were made considering the workflow and other operations. From 4 weeks per section, were one section measures 30 meters, Züblin managed to reach 2 weeks. The authors' task was to investigate for further efficiency and account for the efficiency improvements already made by Züblin. In order to receive a full understanding about the workflow on sight, every step of the process has been followed on one section of the superstructure under the construction process. The technical details have been analyzed such as temperature cracks, reinforcement, stressing and concrete quality. Documents about the project had to be examined and interviews with the involved experts and thoroughly follow the operations on site. Since many efficiency measures were implemented when the authors began this degree project at Züblin, not much space was left for technical efficiency improvements. The efficiencies that caught the attention is mostly working methods and material use where more prefabrication should be utilized considering the reinforcement and forming over pillars, use of rolled reinforcement and self- consolidating concrete. Considering no tests or try-outs have been made this is only speculations which have been discussed with the involved experts with great experience in their field.

[pt] Na engenharia estrutural, um dos critérios de projeto consiste na necessidade de que as estruturas mantenham suas condições de segurança e funcionalidade ao longo da vida útil. Desta forma, diversas metodologias de avaliação da integridade estrutural (SHM) vêm sendo desenvolvidas. Esta avaliação ocorre através do sensoriamento contínuo de estruturas de modo a validar seu comportamento no tempo. A resposta dinâmica pode ser considerada uma metodologia gradualmente explorada como SHM. Estruturas em serviço tendem a sofrer vibrações que geram uma resposta dinâmica. A existência de danos proporciona a degradação de propriedades como massa e rigidez, resultando em variação nos parâmetros modais, como frequências naturais, modos de vibração e amortecimento. Na presente pesquisa, com o auxílio de um modelo de elementos finitos devidamente validado, propõem-se uma metodologia de avaliação de danos através de parâmetros modais experimentais. A proposta será avaliada através da comparação entre respostas numéricas e resultados de ensaios dinâmicos em laje danificada. Objetiva-se estimar a variação de rigidez da estrutura, que corrobora para alteração dos parâmetros dinâmicos. Serão avaliados ainda fenômenos como breathing cracks, fissuras que se encontram abertas ou fechadas em instantes distintos durante a vibração. Além disso, será ponderado o efeito de enrijecimento do concreto na região fissurada. Estes processos afetam consideravelmente a rigidez do elemento fissurado. Desta forma, objetiva-se um modelo robusto de análise de lajes de concreto armado fissuradas a partir da análise do comportamento dinâmico. / [en] In structural engineering, one of the design criteria is the need to maintain structures safety and functionality conditions throughout their useful life. This way, several structural health monitoring methodologies (SHM) have been developed. This evaluation occurs through the continuous sensing of structures in order to validate their behavior over time. Dynamic response can be considered a gradually explored methodology as SHM. In-service structures tend to suffer with vibrations that produce a dynamic response. The existence of structural damage produces a degradation of properties such as mass and stiffness, resulting in variation of modal properties such as natural frequencies, vibration modes and damping. In the present research, with the aid of a duly validated finite element model, it is proposed a damages diagnosis methodology through experimental modal parameters. The proposal will be through the comparison of numerical responses and dynamic tests results made with a damaged slab. The analysis aim to estimate the structure s stiffness variation, which corroborates the alteration of the dynamic parameters. Phenomena such as breathing cracks, where the fissure is open or closed at different times during the vibration, will also be evaluated. In addition, the effect of concrete stiffening around the cracked region will be considered. These processes considerably affect the stiffness of the cracked element. In this way, the objective is a robust model for the analysis of cracked reinforced concrete slabs from the analysis of their dynamic behavior.

No description available.