56 research outputs found

    Betongplattor, ber\ue4kning och dimensionering vid koncentrerade upplagsreaktioner och fria kanter

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    Dimensionering av armerade betongplattor utf\uf6rs i allm\ue4nhet enligt elasticitetsteori varvid finit elementmetod (FEM) mestadels till\ue4mpas for snittkraftsber\ue4kningen. F\uf6r tolkning av ber\ue4kningsresultat och for att v\ue4lja l\ue4mpliga kompletteringar har i denna utredning behandlats \ub7 moment i och kring singul\ue4ra punkter (vid koncentrerade upplagsreaktioner samt vid fritt inre h\uf6rn),\ub7 tv\ue4rkrafter kring koncentrerade upplagsreaktioner m a p genomstansning, och\ub7 tv\ue4rkrafter l\ue4ngs fria kanter och i fritt inre h\uf6rn.Exemplen belyser hur ber\ue4kningsresultaten p\ue5verkas vid variation av olika parametrar och tolkningen ger v\ue4gledning for praktiskt konstruktionsarbete.Plattor med pelarupplag, avslutat linjeupplag, olika typer av in\ue5tg\ue5ende h\uf6rn samt med fri kant har analyserats f\uf6r j\ue4mnt f\uf6rdelad belastning. Fasta, insp\ue4nda, elastiska och fj\ue4drande upplag har till\ue4mpats. Inverkan av varierande st\uf6dv\ue4ggsh\uf6jder och plattjocklekar har studerats. Mindlinelement 1,0x1,0, 0,5x0,5, 0,25x0,25 och 0,125x0,125 m har anv\ue4nts samt i n\ue5gra fall \ue4ven kirchoffelement.\ua0B\uf6jmoment i och kring singulara punkter kan vid dimensioneringen utj\ue4mnas till medelv\ue4rden inom en medverkande bredd. Exemplen med varierande elementstorlek visar att medelmomentet blir m\ue5ttligt beroende av elementstorleken. Vid fritt inre h\uf6rn inverkar inte elementstorleken. I vissa fall b\uf6r inf\uf6ras elastiska stod exempelvis i form av st\uf6djande v\ue4ggar. Olika v\ue4ggh\uf6jder har provats. Att inf\uf6ra fj\ue4derf\uf6rsedda upplagslinjer ist\ue4llet f\uf6r v\ue4ggar ar inte r\ue4ttvisande. Det b\uf6r vara en acceptabel bed\uf6mning att element med en bredd lika med plattjockleken v\ue4l avspeglar plattans funktion kring singulara punkter.For pelarst\uf6d och lageruppl\ue4ggning kan h\ue4nsyn till st\uf6dytans storlek tas genom manuell justering av momenten i och kring den singulara punkten. Enkla formler for medelmoment och toppmoment ges.\ua0Tv\ue4rkrafter kring koncentrerade upplagsreaktioner studeras m a p genomstansning. Metod att ber\ue4kna b\ue4rf\uf6rm\ue5gan m h t stansning framg\ue5r av normer. H\ue4r behandlas f\uf6ljande tillh\uf6rande fr\ue5gor:\ub7\ua0\ua0\ua0\ua0\ua0\ua0 st\uf6dreaktion j\ue4mte excentricitet vid de olika plattgeometrierna,\ub7\ua0\ua0\ua0\ua0\ua0\ua0 till\ue4ggsfaktor f\uf6r variation hos huvudtv\ue4rkraften runt st\uf6det, samt\ub7\ua0\ua0\ua0\ua0\ua0\ua0 inverkan av elastiska st\uf6d.Olika elementstorlekar ger i de studerade plattorna praktiskt taget lika stodreaktioner. Mindlinelement b\uf6r till\ue4mpas. Elastiska stod j\ue4mnar ut reaktioner. Huvudtv\ue4rkrafterna i en krets runt st\uf6dande resp. in\ue5tg\ue5ende h\uf6rn reduceras d\ue5 betydligt. En ber\ue4kning av r\ue4tvinklig och snedvinklig broplatta visar att tv\ue4rkrafterna kan f\uf6rdelas ickerotationssymmetriskt \ue4ven vid centriskt belastade (ledade) pelarst\uf6d.In\ue5tg\ue5ende fritt h\uf6rn \ue4r en singular punkt. Stansningsber\ue4kning inte aktuell. Den utf\uf6rda tolkningen av plattmodellens tv\ue4rkraft st\uf6ds av en balkrostmodell.Ett skadefall beskrivs d\ue4r omfattande skjuvsprickbildning tolkas s\ue5som orsakat av att h\ue4nsyn inte tagits till tv\ue4rkraftsvariationen kring pelarst\uf6d.\ua0Tv\ue4rkraften l\ue4ngs en fri kant utg\uf6rs av ett ”basv\ue4rde” plus ett kanttillskott d\ue4r tillskottet \ue4r lika med vridmomentet strax innanf\uf6r kanten. Tillskottet blir ungef\ue4r lika vid de olika elementstorlekarna. De olika ber\ue4kningsresultaten vid mindlin- resp. kirchoffelement p\ue5visas och anvisningar for tolkning ges.I bilagor\ub7\ua0\ua0\ua0\ua0\ua0\ua0 ges armeringsanvisningar,\ub7\ua0\ua0\ua0\ua0\ua0\ua0 h\ue4rleds analytiskt momenttopp i cirkul\ue4r platta, samt\ub7\ua0\ua0\ua0\ua0\ua0\ua0 visas resultat av j\ue4mf\uf6rande balkrostber\ue4kningar

    Visualisering och auralisering av buller i stadsmilj\uf6

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    Inom dagens stadsplanering anv\ue4nds oftast 2D-kartor f\uf6r att visa ber\ue4knade v\ue4rden f\uf6r framtida bullerniv\ue5er. Dessa kartor kan ibland vara sv\ue5ra att tolka. F\uf6r att \uf6ka f\uf6rst\ue5elsen och underl\ue4tta kommunikationen mellan olika akt\uf6rer inom planeringsprocessen, har vi inom forskningsprojektet DemoVirPEN p\ue5 Chalmers och G\uf6teborgs universitet utvecklat en prototyp av ett verktyg f\uf6r visualisering och auralisering (ljudsimulering) av buller fr\ue5n v\ue4gtrafik i en stadsmodell

    Villkorsutformning f\uf6r grundvattenbortledning vid undermarksbyggande

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    Vid undermarksbyggande och under r\ue5dande grundvattenyta kan grundvatten l\ue4cka in i anl\ue4ggningen. Eftersom arbeten i anl\ue4ggningen samt driften av anl\ue4ggningen i regel m\ue5ste utf\uf6ras i torra milj\uf6er m\ue5ste inl\ue4ckande grundvatten i s\ue5dana situationer ledas bort. Grundvattenbortledning riskerar att skada ekonomiska, kulturella och milj\uf6m\ue4ssiga v\ue4rden. Bortledning av grundvatten och d\ue4rmed anl\ue4ggning av undermarkskonstruktioner kr\ue4ver i regel alltid tillst\ue5nd enligt milj\uf6balkens 11 kapitel. F\uf6r att s\ue4kerst\ue4lla att verksamheten uppfyller milj\uf6balkens m\ue5l och krav fastst\ue4lls vanligen villkor f\uf6r vattenverksamheten i tillst\ue5ndsdomen. Hur dessa villkor utformas kan ha stor p\ue5verkan p\ue5 ett projekts framdrift och utf\uf6rande d\ue5 verksamhetsut\uf6varen ofta m\ue5ste vidta dyra och tidskr\ue4vande \ue5tg\ue4rder f\uf6r att efterleva villkoren. En \uf6vertr\ue4delse av villkoren \ue4r ocks\ue5 straffr\ue4ttsligt sanktionerat. Det \uf6vergripande syftet med denna rapport \ue4r att beskriva sambandet mellan st\ue4llda villkor f\uf6r grundvattenbortledning vid undermarksbyggande och dessas konsekvenser i form av skador, st\uf6rningar och kostnads\uf6kningar. F\uf6r att uppn\ue5 detta syfte har milj\uf6balkens till\ue4mpning vid vattenverksamhet beskrivits utifr\ue5n en litteraturstudie, historiska tillst\ue5ndsdomar har analyserats f\uf6r att beskriva hur villkor har utformats i tidigare projekt, och ett arbetsseminarium med experter inom vattenverksamhet och undermarksbyggande har genomf\uf6rts f\uf6r att beskriva konsekvenserna av olika villkorskonstruktioner. Resultaten fr\ue5n arbetet visar att villkoren i tillst\ue5ndsdomen kan vara mycket kostnadsdrivande och ha stor p\ue5verkan p\ue5 b\ue5de ett undermarksprojekts ekonomi samt dess framdrift om dessa utformas p\ue5 ett of\uf6rdelaktigt s\ue4tt och inte \ue4r \ue4ndam\ue5lsenliga. Rapporten avslutas med rekommendationer f\uf6r hur villkor b\uf6r utformas f\uf6r att undvika eller minska risken f\uf6r dessa negativa konsekvenser

    NÀtverk för ingenjörsutbildningar för samverkan vid införande av ny examens- och utbildningsstruktur

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    I föreliggande arbete beskrivs arbetet med att skapa ett nÀtverk med det övergripande syftet att stÀrka svensk ingenjörsutbildning. Under 2007 har nÀtverket finansierats av NSHU, som tillhandahÄllit medel för att stödja svenska högskolors arbete med Bolognaprocessen. NÀtverket Ingenjörsutbildningarna har under Äret anordnat ett antal vÀlbesökta workshopar. Ett antal grupperingar som inte tidigare haft regelbundna trÀffar har dÀrmed skapats. Deltagarnas omdömen har varit positiva. Det Àr tydligt att det finns ett behov av Àmnesbaserade nÀtverk, och dÀr diskussionerna inte bara handlar om BolognafrÄgor utan Àven om ÀmnesinnehÄll, rekrytering, varumÀrken med mera. Projektet kan sÀgas ha startat ett nÀtverkande mellan ingenjörsutbildningar men det krÀvs mer arbete för att nÄ kontinuitet

    FRAMTIDSSPANING: Hur vill morgondagens seniorer bo?

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    Framtidens seniorer kommer att leva p\ue5 ett helt annat s\ue4tt \ue4n dagens. Medellivssl\ue4ngden f\uf6rv\ue4ntas \uf6ka och vi kommer ha andra behov och krav f\uf6r att kunna leva ett gott liv.Den 24 april 2018 h\uf6lls en konferens p\ue5 temat Hur vill morgondagens seniorer bo

    Interior super insulation in heritage buildings: Challenges and possibilities to conserve heritage values and increase energy performance

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    Super insulation materials (SIM) are insulation material with a very low thermal conductivity, even lower than stagnant air. The aim of the project has been to show how these materials can be used to save energy and space, as well as to contribute to preservation of exterior character defining elements while maintaining the temperature and humidity performance of the walls when renovating buildings built before 1945. The project was performed by researchers in the fields of building physics and building conservation. Brick buildings in Sweden have been in focus, as these buildings have one of the largest energy efficiency potentials in the entire building stock. Brick buildings often challenge engineers and architects by having contradicting demands on energy efficiency and cultural heritage values. Often, the fa\ue7ades of these buildings have valuable character defining elements that make them difficult to insulate. There are also problems with the building components, technical service life and insufficient thermal comfort indoors. Experts in architecture and building conservation have contributed with knowledge through interviews and practical work at study visits and by reviewing drawings and construction documents. Collaboration partners, linked to the reference group, contributed to the project with their knowledge in interviews, meetings and seminars. The project has led to an increased knowledge and understanding of the technical difficulties that exist when preserving character defining elements while imposing energy efficiency measures with super insulation materials in buildings. Advantages of super insulation materials are, for example, that they add little thickness to the walls and that the flexible materials, such as aerogel blankets, can contribute to preservation of character defining elements in heritage buildings. The disadvantage of using super insulation materials as interior insulation is, as for all insulation materials, that the lowered temperatures in the wall can lead to increased moisture levels and also that the drying out capacity of the wall can decrease. Due to the risks with interior insulation of walls, it is important to thoroughly investigate if the wall is suitable for interior insulation

    Economic valuation of drinking water quantity and quality: A literature review

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    This literature review is a part of the research project Risk-based prioritization of water protection in sustainable spatial planning (WaterPlan), funded by the Swedish research council Formas. The aim of the project is to enable well-informed analyses and prioritization of measures for protecting water sources as a part of future urban development. One key to prioritization is knowledge about the economic values of drinking water quality and quantity. The purpose of the literature review is therefore to map earlier studies of such values, and to use this mapping for (a) evaluating the opportunities to transfer results from earlier studies to a Swedish setting, and (b) learning from earlier experience how potential new primary valuation studies in a Swedish setting could be designed.The literature review allowed some main valuation situations among the studies to be identified. Based on these different situations, the following rough categorization of studies was performed: i. Improvements in water quality/quantity (10 studies)ii. Preservation of water quality/avoiding water quality deterioration (5 studies)iii. Avoiding quantity restrictions/ensuring stable supply (6 studies)iv. WTP to reduce risks to drinking water sources (5 studies)v. Meta and benefit transfer studies (8 studies)vi. National valuation studies (6 studies)The report includes a listing of all identified studies according to this categorization.The results from the literature review indicate that there is a lack of suitable value estimates to allow for benefit transfer to Swedish conditions to evaluate the drinking water service in relevant policy scenarios. It is therefore concluded that new valuation studies might be needed for fulfilling the objectives of the WaterPlan project.One possible approach for carrying out new valuation studies is to follow the demand function approach. This approach is therefore reviewed, but it is found that the approach entails some important weaknesses for the case of Sweden. One important reason is that there is not an actual well-functioning market for drinking water in Sweden. The report therefore also reviews the use of stated preference studies for valuing drinking water quantity and quality. This review indicates experiences that can be helpful in the development of new valuation studies in Sweden which follow the stated preference approach

    Evaluation of hospital ward layouts in recent norwegian hospitals

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    Objective – This paper presents current results from evaluations of two recently built Norwegian hospitals and aims towards collecting data to develop guidelines for hospital ward layouts. Background – There is a growing interest in making decisions on hospital design based on evidence and post occupancy evaluations. Research question – Which design solutions, investigated in evaluations of different hospitals, can give valuable input to guidelines for best design and layout principles of hospital wards? Methods – Six hospital cases were chosen to represent different layout solutions of ward design. This paper presents and compares two of them. The methods included assessment of floorplans, walk-through evaluations with hospital staff, semi-structured focus group interviews and individual interviews. The combination of methods was used to investigate layout of wards, workstations and patient rooms. Focus was also on patients’ comfort and possibilities of observation of patients as well as work processes in the workstations. Data and photos of specific areas were collected, interviews transcribed, analysed and summarised. Results – The results show both similarities and variations in design solutions concerning architectural layouts of wards, workstation, patient room and bathroom. The cases have following common features: Single-bed patient rooms, large windows providing daylight and view, wards divided into 3 smaller units – bed clusters organized around workstations, each monitoring 8-9 patient rooms. Both hospitals have open workstations located in the corridor and including a small glass-sheltered work area and ‘support rooms’ nearby. Differences: The distance and visual contact between the workstations and the patient beds vary. One ward case provides bathrooms shared by two adjacent patient rooms, the other a private bathroom for each patient room. Furthermore, one ward includes a centrally placed patient leisure/waiting room with library while the other offers several small social areas for patients in addition to kitchen/dining room. Perceived comfort, satisfaction and functionality differ relating to the design solutions. The linear design of wards gave a better overview and shorter walking distances than the L-shape. Open workstations functioned well and made the staff available for patients and nearest relatives but showed challenges with confidentiality and capacity. Both patients and staff were satisfied with single-bed rooms and report improved rest, confidentiality and containing infections. Conclusion – The current evaluation provides preliminary results for design solutions concerning layout of wards, workstations and patient rooms. These solutions are associated with positive impact on experiences of architectural quality, functionality and patient and staff satisfaction and may therefore influence current guidelines for hospital wards.publishedVersio

    Hur kan Chalmers biblioteks onlinemodul \uf6ka studenternas kunskap i informationskompetens?

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    2016 skapade Chalmers bibliotek en onlinemodul, Chalmers Library Education Online (CLEO) riktad till kandidatarbetare f\uf6r att \uf6ka deras informationskompetens. Vi kommer att presentera arbetet med CLEO 2.0 i Canvas med f\uf6rhoppningar att \ue4ven mastersprogram skulle kunna integrera den engelska versionen i befintliga kurser

    Set-Based Design of Frame Bridges - Development and Implementation

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    The traditional design process of bridges in structural engineering is based on the design approach called Point-Based design. To minimize environmental impact and industrialize the design process, the theory of Set-Based design (SBD) has been recognized as a promising approach. Since frame bridges is one of the most common bridge types in Sweden, the main objective of this thesis is to develop and implement a SBD tool for frame bridges.To be able to evaluate the different design alternatives generated by the design tool, evaluation criteria within buildability and sustainability are identified. Buildability is a concept within building industry that aims to improve productivity and safety within on-site production while also reducing the costs of the construction process. The building industry is one of the major contributors regarding impact on its surrounding. Therefore, there is a huge potential in improving the sustainability within the building industry. Sustainability is divided in Environment, Social and Economy aspects.The design tool allows performing an automated and iterative structural preliminary design of several frame bridge alternatives specified within ranges of design parameters. The design alternatives are analyzed with Finite Element Analysis (FEA) and evaluated according to predefined evaluation criteria. By scripting the design tool in programing language Python, it is possible to control an FEA program, such as Brigade Plus, from the design tool as well as performing a preliminary design of frame bridges. The preliminary design is performed according to requirements in national building codes, Eurocode.Finally, a case study is performed to investigate how a SBD tool can be implemented in an infrastructure project containing several frame bridges. In a large infrastructure project and with a SBD tool it is possible to find one optimum bridge solution that fulfills the need of several bridges in a set of bridges. The contractor can then industrialize parts of the construction of frame bridges, hopefully leading to a more sustainable and cost-effective building of frame bridges
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