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Timber Shear Wall Analysis : Parameterized Finite Element ModellingKormendy, Imre, Muwaili, Mustafa January 2018 (has links)
This paper investigates the linear elastic behavior of timber shear walls under monotonic prescribed displacement. ABAQUS© 16.4-5, is a numerical finite element software used as the primary analysis methodology. Parameterized models are created for two shear wall specimens of different geometry concerning door and window configurations. The shear walls are simulated as solid timber framing which is mechanically connected to gypsum sheathing board through fasteners. The primary findings are the linear elastic shear force distribution of the mechanical joints. Additionally, deformations and reaction forces of the shear walls are determined. The overall horizontal shear wall behavior of each specific wall was also studied in the presence of door and window openings. The simulations indicate there is a clear deformation difference in the behaviors of the two shear walls. Furthermore, the highest shear force values of the fasteners are located around the corners of the openings. The findings are supported by other researcher’s experiments and analytical tests, timber shear wall theory and Eurocode design requirements.
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Swimming Pool on top of High-Rise Buildings : A comparison of different structural designs and positions of swimming poolsMUSINOVIC, ERVIN, CARLSSON, MATHIAS January 2021 (has links)
This thesis is about determining the risks of positioning swimming pools on top of high-rise buildings.Pursuing this determination, computational simulations of constructed structural models in a finiteelement model software called RFEM have been analyzed. In further pursuit of wanted results comingfrom the computational software, the models have acquired relevant theory regarding both swimmingpools and high-rise buildings respectively to obtain realistic approximations of equivalent results if themodels were real life structures. Thence analytical observations and measures of each structural modelcontaining different positions of the swimming pools are generated, in several degrees, differentpossibilities of risks of failure are possible. Results have been compared out of design of swimmingpools and high-rise buildings in an initial stage of background and thereafter set as input values for themodeling where following perspectives have been analyzed:• Structural deformations,• Internal forces,• Utilization ratios, and• Mode shapes.Further analysis of social-, economic-, and environmental sustainability have been deliberated. Thus,in conclusion of this thesis, swimming pools positioned on top of the structure core or at center of theplan section tend to harm the stability of the structure likewise if the positioning of the swimming poolare cantilevered completely over the edge of the rooftop. More suitable design would either bepositioning the swimming pool attached to the core of the structure meanwhile cantilevered over theedge or integrated entirely along the edge.The results showed that some of the overhanging swimming pools pass the requirements of theEurocode. This will result in the columns experiencing a utilization which exceed its capacity. Thecolumn utilization was shown to behave differently depending on where the swimming pool was placedon the top floor. Furthermore, it was also a difference between the structures studied as dimensions ofthe members required either more or less depending on the form the structure had. The reaction of theswimming pool could be observed to behave as a stiff part of the structures with the deformation mostlybeing located at the slabs. The internal forces developed in the members due to the swimming poolaffected the columns at the bottom floors the most. The thesis finally shows how much is needed forthe worst case of each structure to pass the requirements. This resulted in different dimensions for themembers where the smaller structure (structure model 1) needed bigger dimensions and the largerstructure (structure model 2) needed smaller dimensions compared to the originally based dimensions.The social, economic, and environmental impact of the structures showed that the larger structureswould release more carbon dioxide than the smaller structures. The social aspect was treated moreregarding the safety and the experience of the user of the facility of swimming pool. The reinforcementvaried the most between the structures with the concrete being mostly the same for the two differentstructures made, in which an impact was made for both the economic and the environmental. Here itwas shown that in order to pass the requirements of the Eurocodes the impact on the climate needed tobe considerable different.
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Shear cracks in concrete structures subjected to in-plane stressesMalm, Richard January 2006 (has links)
After only two years of service, extensive cracking was found in the webs of two light-rail commuter line bridges in Stockholm, the Gröndal and Alvik bridges. Due to this incident it was found necessary to study the means available for analysing shear cracking in concrete structures subjected to in-plane stresses. The aim of this PhD project is to study shear cracking with these two bridges as reference. In this thesis, the first part aims to study the possibility of using finite element analysis as a tool for predicting shear cracking for plane state stresses. The second part is concerning how the shear cracks are treated in the concrete design standards. Shear cracking in reinforced beams has been studied with non-linear finite element analyses. In these analyses the shear cracking behaviour was compared to experiments conducted to analyse the shear failure behaviour. Finite element analyses were performed with two different FE programs Abaqus and Atena. The material model used in Atena is a smeared crack model based on damage and fracture theory with either fixed or rotated crack direction. The material model used in Abaqus is based on plasticity and damage theory. The fixed crack model in Atena and the model in Abaqus gave good results for all studied beams. For the two studied deep beams with flanges the results from the rotated crack model were almost the same as obtained with the fixed crack model. The rotated crack model in Atena gave though for some beams a rather poor estimation of the behaviour. The calculation of crack widths of shear cracks has been studied for the long-term load case in the serviceability state for the Gröndal and Alvik bridges, with the means available in the design standards. The methods based on the crack direction corresponding to the principal stress and do not include the effect of aggregate interlocking seems to be too conservative. Two of the studied methods included the effect of aggregate interlocking, it was made either by introducing stresses in the crack plane or implicitly by changing the direction of the crack so that it no longer coincide with the direction of principal stress. For calculations based on probable load conditions, these methods gave estimations of the crack widths that were close to the ones observed at the bridges. Continuous measurements of cracks at the Gröndal and the Alvik bridges have also been included. Monitoring revealed that the strengthening work with post-tensioned tendons has, so far, been successful. It also revealed that the crack width variations after strengthening are mainly temperature dependent where the daily temperature variation creates movements ten times greater than those from a passing light-rail vehicle. Monitoring a crack between the top flange and the webs on the Gröndal Bridge showed that the top flange was moving in a longitudinal direction relative to the web until the strengthening was completed. The crack widths in the sections strengthened solely by carbon fibre laminates seem to increase due to long-term effects. / QC 20101119
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FE safety analysis of a high speed wood planer cutter. An alternative method to achieve the requirements of EN847 standard / FE safety analysis of a high speed wood planer cutter. An alternative method to achieve the requirements of EN847 standardMarques Novo, Francisco José, Saraiva Rézio, Henrique Manuel January 2004 (has links)
<p>In the last decades, high speed cutting has become an attractive technology in the wood industry. The possibility of reducing global costs in addiction with an increase in productivity, were the main reasons for the enlargement of the use of this technology. </p><p>As usual, these advantages are accompanied by disadvantages that should be carefully analyzed. If on the one hand cutting forces are reduced with increasing cutting speeds, on the other hand, the centrifugal forces affecting the tool are higher. Exposed to such high loads, there is a considerable risk of tool failure that embeds hazards for both machine and workers. </p><p>To prevent the risk of accidents and to guarantee safety in use, security standards have been implemented in industrial fields, imposing specific experimental tests, with defined procedure modes. Accordingly with these standards, the results obtained through the tests should fall inside limited ranges. The experimental tests suggested on the European Standards are intended to simulate the real working conditions of a rotating cutting tool, where extreme centrifugal forces are imposed by the high values of speed. Although their main importance, these destructive tests aren’t always practicable. It happens, for instance, with tools produced in small batch sizes, or as an ascertainment for the fail-critical speed during the development stage, or even due to physical incompatibilities between the tool and the laboratory testmachines. </p><p>The high value of weight associated with the cutting tool prototype developed and patented by Verktygs Larsson AB was an impediment to run the laboratorial tests specified by the standards, forcing the company to find a new way to assure the safety requirements of their product. </p><p>The main goal of this project was the development of an alternative method based on finite element theory to perform a safety analysis to the prototype of a wood cutter. This tool is used as a component in high speed planers. </p><p>In addiction to this primary objective, some considerations were made about other available models, with increased dimensions or even with different parameters. If there was the need, design changes could be assumed in order to guarantee that the tool reached the requisites of the safety standards. Considering an optimization effort, material changes would also be considered, to aim in the direction of reducing the tool weight and the consequent centrifugal forces.</p>
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FE safety analysis of a high speed wood planer cutter. An alternative method to achieve the requirements of EN847 standard / FE safety analysis of a high speed wood planer cutter. An alternative method to achieve the requirements of EN847 standardMarques Novo, Francisco José, Saraiva Rézio, Henrique Manuel January 2004 (has links)
In the last decades, high speed cutting has become an attractive technology in the wood industry. The possibility of reducing global costs in addiction with an increase in productivity, were the main reasons for the enlargement of the use of this technology. As usual, these advantages are accompanied by disadvantages that should be carefully analyzed. If on the one hand cutting forces are reduced with increasing cutting speeds, on the other hand, the centrifugal forces affecting the tool are higher. Exposed to such high loads, there is a considerable risk of tool failure that embeds hazards for both machine and workers. To prevent the risk of accidents and to guarantee safety in use, security standards have been implemented in industrial fields, imposing specific experimental tests, with defined procedure modes. Accordingly with these standards, the results obtained through the tests should fall inside limited ranges. The experimental tests suggested on the European Standards are intended to simulate the real working conditions of a rotating cutting tool, where extreme centrifugal forces are imposed by the high values of speed. Although their main importance, these destructive tests aren’t always practicable. It happens, for instance, with tools produced in small batch sizes, or as an ascertainment for the fail-critical speed during the development stage, or even due to physical incompatibilities between the tool and the laboratory testmachines. The high value of weight associated with the cutting tool prototype developed and patented by Verktygs Larsson AB was an impediment to run the laboratorial tests specified by the standards, forcing the company to find a new way to assure the safety requirements of their product. The main goal of this project was the development of an alternative method based on finite element theory to perform a safety analysis to the prototype of a wood cutter. This tool is used as a component in high speed planers. In addiction to this primary objective, some considerations were made about other available models, with increased dimensions or even with different parameters. If there was the need, design changes could be assumed in order to guarantee that the tool reached the requisites of the safety standards. Considering an optimization effort, material changes would also be considered, to aim in the direction of reducing the tool weight and the consequent centrifugal forces.
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FE analysis of a dog clutch for trucks withall-wheel-drive / FE-analys av en klokoppling för allhjulsdrivna lastbilarAndersson, Mattias, Goetz, Kordian January 2010 (has links)
The thesis is carried out in order to improve the transfer case in trucks with all-wheel-drive. When the truck loses traction at the rear wheels, due to slippery surfaces, wheel-spin occurs. If the driver engages the all-wheel-drive at a point where traction already has been lost, a relative rotational speed in the dog clutch will occur. If this relative speed is too high the dog clutch bounces of itself before coupling or it does not couple at all. To avoid this problem, the geometry of the teeth is modified. FE simulations are done for the existing model as well as for all the new models in order to find out which of them can handle the highest relative rotational speed. The results show that the original model is not the best one. Simple modifications of the teeth’s chamfer distance and chamfer angle shows that the dog clutch can handle up to 120 rpm of relative rotational speed whereas the original model only handles 50 rpm. / Examensarbetet är utfört för att försöka förbättra inkopplingen av allhjulsdrift på lastbilar. När en lastbil kör på halt eller löst väglag kan hjulspinn uppstå vid bakhjulen. Om föraren kopplar in allhjulsdriften när hjulen börjat slira uppstår en relativ rotationshastighet mellan halvorna i klokopplingen. Om denna relativa rotationshastighet är för hög kommer halvorna i kopplingen studsa mot varandra innan de kopplas ihop eller inte koppla ihop alls. För att undvika detta problem har klokopplingens tandgeometri modifierats. FE simuleringar är gjorda på den ursprungliga modellen samt alla nya modeller för att ta reda på vilken som kopplar vid högst relativa rotationshastighet. Resultaten visar att förbättringar kan göras. Enkla modifieringar på avfasningarnas avstånd och vinklar visar att klokopplingen kan klara upp till 120 rpm i relativ rotationshastighet jämfört med den ursprungliga modellen som endast klarar 50 rpm.
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Multi-axial fracture behaviour of notched carbon-fibre/epoxy laminatesTan, Julian Lip Yi January 2015 (has links)
Carbon-fibre reinforced polymer (CFRP) laminates are widely used in various engineering applications, such as in race cars and aircrafts, because they are light, stiff and strong. They commonly contain stress raisers in the form of holes and notches (for mechanical joining methods, routing of pipes and cables etc.) and are also often subjected to complex combined multi-axial stress conditions during service. Yet their notched multi-axial fracture behaviour remains largely unexplored. This is the main contribution of the thesis. First, a novel loading fixture for applying a wide range of in-plane loading modes is developed based on the popular Arcan’s method. Termed the ‘modified Arcan rig’, it utilises friction gripping to transfer loads into tabbed specimens. This loading fixture is used to test centre-notched multi-directional CFRP laminates under different combinations of tension and shear stresses. Together with penetrant-enhanced X-ray CT and laminate de-ply, the fracture behaviour of quasi-isotropic CFRP specimens is investigated for the following loading modes: pure tension, pure compression, in-plane shear, and combined tension and shear. Two notch geometries (sharp notch and circular hole) are investigated to allow for an assessment of the role of stress concentration upon strength and damage development to be performed. Three distinct fracture modes are observed in a tensile/compressive-shear stress space (termed Mechanism A, Mechanism B and Mechanism C). It is observed that quasi-isotropic specimens with a central sharp notch are consistently stronger than equivalent specimens with a central circular hole (for all stress states investigated). An underlying micromechanical explanation concerning the effects of damage upon strength is proposed. Second, a finite element (FE) model is developed using the commercial FE program, Abaqus FEA to simulate the observed progressive damage and failure in the quasi-isotropic specimens. The FE model employs independent material property data as inputs. Overall, good correlation between the simulations and the experiments is obtained, validating the FE strategy. The capabilities of the model are extended to predict the notched fracture behaviour of the specimens under combined compression and shear loading, for which experimental work has not been done by the author, but for which literature data exists. Finally, the effect of laminate lay-up upon the notched multi-axial fracture behaviour of the CFRP specimens is explored by considering a 0° ply-dominated lay-up, a ±45° ply-dominated lay-up and a cross-ply lay-up, alongside the quasi-isotropic lay-up. Experiments reveal that all lay-ups exhibit Mechanisms A, B and C. However, the extent of damage in each Mechanism as well as the regime in which each Mechanism operates in (in the failure envelopes) strongly depend on the lay-up of the specimen. As expected, the tensile strengths and compressive strengths increase with the proportion of 0° plies. Surprisingly, the shear strengths do not scale with the proportion of ±45° plies; the specimen geometry and material orthotropy are attributed as reasons for this. In contrast to the case of the quasi-isotropic lay-up, the extent of subcritical damage induced by the circular hole is not always lower than that induced by the sharp notch for the other lay-ups. The difference in the extent of damage between both notch geometries is reflected in the notched strengths of the lay-up in question. These experimental observations are adequately predicted by the FE strategy, which further validates it as a reliable predictive tool for composite fracture.
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Warhead penetration in concrete protective structuresHansson, Håkan January 2011 (has links)
The analysis of penetration of warheads in concrete protective structures is an important part of the study of weapon effects on protective structures. This type of analysis requires that the design load in the form of a warhead is determined, and its characteristic and performance within a protective structure is known. Constitutive equations for concrete subjected to weapon effects have been a major area of interest for a long time, and several material models for concrete behaviour are developed. However, it is not until recent years that it has been possible to use finite element (FE) analyses to simulate the behaviour of concrete targets during projectile penetration with acceptable results. The reason for this is a combination of several factors, e.g. development of suitable material models for concrete, enhancement of numerical methodology and affordable high capacity computer systems. Furthermore, warhead penetration has primary been of interest for the armed forces and military industry, with a large part of the conducted research being classified during considerable time. The theoretical bases for concrete material behaviour and modelling with respect to FE analyses of projectile penetration are treated in the thesis. The development of weapons and fortifications are briefly discussed in the thesis. Warheads may be delivered onto a protective structure by several means, e.g. artillery, missiles or aerial bombing, and two typical warhead types were used within the study. These warhead types were artillery shells and unitary penetration bombs for the use against hardened targets, with penetration data for the later warhead type almost non-existing in the literature. The penetration of warheads in concrete protective structures was therefore studied through a combination of experimental work, empirical penetration modelling and FE analyses to enhance the understanding of the penetration phenomenon. The experimental data was used for evaluation of empirical equations for concrete penetration and FE analyses of concrete penetration, and the use of these methods to predict warhead penetration in protective structures are discussed within the thesis. The use of high performance concrete increased the penetration resistance of concrete targets, and the formation of front and back face craters were prevented with the use of heavily reinforced normal strength concrete (NSC) for the targets. In addition, the penetration depths were reduced in the heavily reinforced NSC. The evaluated existing empirical penetration models did not predict the behaviour of the model scaled hardened buried target penetrators in concrete structures with acceptable accuracy. One of the empirical penetration models was modified to better describe the performance of these penetrators in concrete protective structures. The FE analyses of NSC gave reasonable results for all simulation cases, with the best results obtained for normal impact conditions of the penetrators. / Analyser avseende stridsdelars penetration i skyddskonstruktioner av betong viktigt för studier av vapenverkan mot skyddskonstruktioner. Dessa analyser förutsätter att dimensionerande last i form av stridsdel bestäms, samt att dess karakteristik och verkan mot skyddskonstruktioner är kända. Konstitutiva modeller för betong utsatta för vapenverkan har varit av stort intresse under en lång tid och ett flertal materialmodeller har utvecklats. Det är emellertid först på senare år som det varit möjligt att använda finita element (FE) analyser for att simulera beteendet för betongmål vid projektilpenetration med acceptabla resultat. Anledningen till detta kan tillskrivas kombinationen av ett flertal faktorer, t ex utvecklingen av lämpliga materialmodeller, förbättringar av numerisk metodik och utvecklingen av kostnadseffektiva beräkningsdatorer. Penetration av stridsdelar har dessutom i huvudsak varit av intresse för militären och försvarsindustrin, vilket har resulterat i att en stor del av den bedrivna forskningen har varit hemligstämplad under lång tid. Grunderna avseende betongs materialbeteende och beskrivning av detta med avseende på FE-analyser av projektilpenetration behandlas i denna licentiatuppsats. Den fortifikatoriska utvecklingen och utvecklingen av vapen diskuteras kortfattad i uppsatsen. Ett flertal olika typer av stridsdelar är av intresse avseende verkan mot skyddskonstruktioner, t ex artillerigranater, missiler eller flygbomber. I denna studie beaktades två typiska stridsdelar, artillerigranater och penetrerande bomber. De senare är specifikt konstruerade för användande mot skyddskonstruktioner och företrädesvis mot betongkonstruktioner. Det visade sig dessutom att data avseende penetration i betong för denna typ av penetrerande stridsdelar i stort sett inte var publicerade. Penetration av stridsdelar i betong studerades därför med en kombination av experimentella metoder, empiriska penetrationsmodeller och FE-analyser för att öka förståelsen för problemställningen. De experimentella modellresultaten användes för att utvärdera både de empiriska penetrationsmodellerna och FE-analyserna avseende betongpenetration, med båda metodernas användande diskuterat i uppsatsen. Användandet av högpresterande betong ökade penetrationsmotståndet för betongmålen i jämförelse med standardbetongmålen. Det var även möjligt att förhindra kraterbildningen på fram- och baksidan av de kraftigt armerande standardbetongmålen, detta medförde även en reducerad penetration för projektilerna i målen. De existerande empiriska penetrationsmodellerna kunde inte förutsäga penetrationen av modellprojektilerna i betongmålen med godtagbara resultat. Istället vidareutvecklades en av dessa modeller för att bättre beskriva denna typ av penetrerande stridsdelar i skyddskonstruktioner av betong. Finita elementanalyserna av standardbetongmålen visade sig ge ett rimligt beteende för alla analyserade modeller, med de bästa resultaten erhållna för vinkelrätt anslag för de modellprojektilerna av de penetrerande stridsdelarna. / QC 20111116
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Utveckling av koncept för ny åkprofil till bakgavellyft : Produktutveckling och konstruktionFritzon, Gustav January 2022 (has links)
Detta examensarbete har utförts i samarbete med Z-lyften Produktion AB som tillverkar bakgavellyftar till lastbilar. En av deras modeller har funktionen att den kan köras in under lastbilen eller trailern. Lyften rullar då på hjul i så kallad slädprofiler som i sin tur är fästa mot lastbilen med ramfästen. Dessa profiler är i dagsläget tillverkade i stål och dimensionerade efter lasterna i arbetsläget vilket gör att de är överdimensionerade över resten av dess längd. Detta gör dem onödigt tunga. De är också svåra att kapa till olika längder och det finns en önskan att göra ramfästena flyttbara. Syftet med detta arbete blev därför att minska profilens vikt och därmed ge miljö- och arbetsmäss-iga vinster, göra fästena flyttbara för enklare montage på lastbil samt medge enklare kapning för effektivare produktion. Målet var att genom en produktutvecklingsprocess presentera ett koncept i form av en 3D-modell på en ny konstruktion av åkprofilen som uppfyller ovan nämnda syfte. En förstudie gav en överblick av konkurrensen och samtal med intres-senter gav en omfattande produktspecifikation att utgå ifrån i det fortsatta arbetet. Produktens önskade funktioner analyserades och dellösningar till dessa söktes sedan i ett antal källor. Detta ledde fram till en rad lös-ningar som kombinerades till fyra koncept varav ett valdes ut för detaljkonstruktion som utfördes med analytiska och numeriska beräk-ningar. Det slutgiltiga konceptet bestod i en aluminiumprofil med spår för flyttbara fästen och glidlager av plast i stället för hjul. Konceptet gav enligt en uppskattning en viktbesparing på 20% jämfört med den nuvarande och profilen i sig blev 60% lättare. Kostnadsmässigt gav själva profilen en besparing på 13% men totalt riskerar konceptet att bli dyrare än den ursprungliga lösningen då förstärkningar av stål behövs i arbetsläget. / This thesis is written in cooperation with Z-lyften Produktion AB which is a manufacturer of tail lifts for trucks. One of their models works by enabling the operator to stow the tail lift under the truck or trailer. The tail lift is in this case mounted on wheel brackets with steel wheels that rolls inside slide profiles. The slide profiles are mounted to the truck frame. Currently, these profiles are made from steel, and they are dimensioned to withstand the loads that are present when the lift is in operation. Therefore, the slide profiles are excessively dimensioned across the length except where the wheels are positioned during operation which causes them to be unnecessarily heavy. The steel profile is difficult to cut in production and there is also a desire to have mounting brackets that can be positioned more freely on the profile. Regarding this, the purpose of this work was to make the profiles lighter to reduce the environmental impact as well as improve the working environment in the production facility, make the mounting brackets more flexible to make the mounting process easier and to make the cutting process easier. The goal was to provide the company with a concept in the form of a 3D-model that fulfils the above purpose. A feasibility study provided an overview of the competition and meetings with stakeholders gave the comprehensive list of product specifications that was the foundation for the rest of the process. The desired functions of the product were analysed and solutions to the functions was then gathered from several sources. The identified possible solutions were then combined into four concepts of which one concept was selected for further development and dimensioning with analytical and numerical methods. The final concept is based on an extruded aluminium profile with polymer slide bearings and T-shaped slots for the mounting brackets. A rough estimate pointed to a weight saving of about 20% for the concept as a whole and the slide profiles alone was 60% lighter. The new profiles gave a cost reduction of 13% but the concept as a whole runs the risk of becoming more expensive than the current solution. / <p>2022-07-01</p>
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Vattentäta betongkonstruktioner utsatta för tvångskrafter : Finit elementanalys av tvångsfördelning för vanliga typfall / Waterproof concrete structures exposed to restraint forces : Finite element analysis of restraint distribution for common casesDe Barros Cruz, Julio Cesar, Paunovic, Marijana January 2019 (has links)
Betong är ett av de mest använda byggnadsmaterialen i dagens samhälle. Några av anledningarna till detta är att den har lång livslängd, är naturligt material som är 100 % återvinningsbart samt ej lättantändligt material. Även om betong har många fördelar så är den inte helt idealisk eftersom den har en låg draghållfasthet. En betongkonstruktion kan spricka på grund av förhindrade rörelser som skapar dragspänningar. Förhindrade rörelser kallas för tvång och kan beskrivas i form av en tvångsfaktor. I detta examensarbete definieras tvångsfaktor som en spänningskvot mellan påtvingade spänningar och påtvingade spänningar vid fullständigt tvång. Fastlåsningsgrad, rörelsemöjlighet och styvhetsrelation mellan det nygjutna elementet och motgjutningen är avgörande parametrar vid beräkning av tvång och ett typiskt fall kan exempelvis vara en vägg gjuten mot grund. En helt förhindrad konstruktion kan ha en tvångsfaktor som är lika med 1 medan en konstruktion som kan röra sig fritt kan ha en tvångsfaktor som är lika med 0. En relativ lägre tvångsfaktor fås däremot om krypningseffekten beaktas eftersom den har gynnsam inverkan på tvånget. Betongen kan spricka på grund av tvånget och om sprickan inte är förväntad eller är större än den förväntade för den dimensionerade lasten då betraktas den som skada. Att förhindra vattengenomträngning eller läckage innebär dessutom att genomgående sprickor i vattentäta betongkonstruktioner bör undvikas. Det är således viktigt att beakta tvånget vid sprickriskanalyser av vattentäta betongkonstruktioner. Syftet med det här examensarbetet var att undersöka tvånget utifrån flera aspekter vilket gjorde att arbetet uppdelades i 3 analyser. Analys 1 syftade på att bekräfta de typiska fallen som anges i eurokoden SS-EN 1992–3 samt att utvärdera angivna tvångsfaktorer vid beräkning av tvångsdeformationer. Följaktligen användes finita elementprogram för modellering av de fallen från eurokoden och samtidigt gjordes handberäkningar för att komplettera analysen. I analys 2 studerades hur tvånget påverkas mellan konstruktionsdelar med ändring av bärverksdimensioner. Bärverket som studerades var vägg gjuten mot bottenplatta. Föränderliga parametrar var plattans bredd och tjocklek samt väggens höjd och tjocklek. Samtidigt togs ändring av konstruktionens längd som en påverkande faktor. Slutligen gjordes sprickviddsberäkningar avseende böjande moment och krympning i analys 3 för att få fram armeringsmängderna som skulle klara sprickviddskravet för vattentäta betongkonstruktioner. Detta åstadkoms enligt två olika beräkningsmetoder: Eurokodens och Engströms (2014). Dessa beräkningar visade även en jämförelse i armeringsmängd vid användning av tvångsfaktorer hämtad från eurokoden och tvångsfaktorer framräknad enligt FE-analyserna. Resultaten från analys 1 visade att variationen av beräknade tvångsfaktorer inte motsvarade helt den variationen som anges i SS-EN 1992–3 men avvek inte alldeles för mycket. Det fanns dock några enstaka fall där avvikelser var märkbara och därmed erfordras en noggrannare undersökning. Analys 2 visade att ökning av väggens volym minskar tvånget mot plattan men att en motsatt effekt fås för ökning av plattans volym. Det visade sig dessutom att en längre konstruktion orsakar större tvång mellan själva konstruktionsdelar. Slutsatsen från analys 3 var att skillnaden i genererad armeringsmängd var nästan proportionell i procentsats mot skillnaden i tvångsfaktor. Olika beräkningsmetoder resulterade dock i armeringsmängder som inte var jämförbara. Jämförelsen mellan de två beräkningsmetoderna var inte heller syftet med detta examensarbete utan endast ett försök att få en insyn i hur de olika metoderna är uppbyggda. / Concrete is one of the most widely used building materials in society today. Some of the reasons for this are that it has a long life, is a natural material that is 100% recyclable and non-flammable material. It has many advantages, but it is not entirely ideal due to its low tensile strength. A concrete structure may crack due to restrained movements which creates tensile stresses. Restrained movements are called restraint which can be described in the form of restraint factor. In this thesis, restraint factor is defined as a ratio between the actual imposed stress and the imposed stress at full restraint. The degree of fixity, movement possibility and stiffness relation between the newly casted element and the adjacent old structure are crucial parameters in the calculation of restraint and a typical case is, for example, a wall-on-slab cast. A completely restrained construction has a restraint factor equal to 1, while a structure that can move freely has a restraint factor equal to 0. However, a relative lower restraint factor is obtained if the creep effect is considered, since it has a positive influence on the restraint. The concrete may crack due to the restraint and if the crack is not expected or is larger than the expected for the dimensioned load then it is considered as damage. Preventing water penetration or leakage also means that through cracks in waterproof concrete structures should be avoided. Therefore, it is important to consider the restraint on fracture risk analyzes of waterproof concrete structures. The purpose of this thesis was to investigate the restraint based on several aspects, which meant that the work was divided into 3 analyses. Analysis 1 had as purpose to confirm typical cases specified in Eurocode SS-EN 1992–3 and to evaluate the stated restraint factors that the Eurocode proposes should be used in calculations of restraint deformations. For that matter, finite element program was used for modeling the cases from the Eurocode and at the same time hand calculations were made to supplement the analysis. Analysis 2 consisted of examining how the restraint between structural parts is affected by changing dimensions of the structure. The construction being studied was wall-on-slab cast. Variable parameters were the width and thickness of the slab, as well as the height and thickness of the wall. At the same time, changing the length of the construction was taken as an affecting factor. Lastly, crack width calculations for bending moments and shrinkage were made in analysis 3 to obtain the amount of reinforcement that meet the crack width requirement for waterproof concrete structures. This was done according to two different calculation methods: Eurocodes and Engström’s (2014). These calculations also showed a comparison in the amount of reinforcement when using restraint factors derived from Eurocode and restraint factors calculated according to the FE analyses. The results from analysis 1 showed that the variation of restraint factors calculated did not completely correspond to the variation stated in SS-EN 1992–3 but did not deviate too much. However, there were a few cases where deviations were noticeable and therefore a more detailed examination is required. Analysis 2 showed that increasing the volume of the wall reduces the restraint against the slab, but an opposite effect was obtained by increasing the volume of the slab. At the same time, it was found that a longer construction causes greater restraint between the actual components. The conclusion from analysis 3 was that the difference in generated amount of reinforcement was almost proportional in percentage to the difference in restraint factor. However, using different calculation methods resulted in amounts of reinforcement that were not comparable. Comparison between the two calculation methods was not the purpose of this thesis, but merely an attempt to gain an insight into how the different methods are structured.
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