Purpose: The purpose of the study is to identify communication problems in the planning process between the architect and the structural engineers in building framework of wood and concrete structures in multi-storey buildnings and investigate the causes of these problems. Wooden frames in multi-storey buildings is on rising and challenges the dominant concrete frames. Difficulties in cooperation between disciplines can not be underresimated, especially in complex projects. Communication is a complex process and the key to project performace. Method: The study consists of a qualitative approach. The used methods are interviews and literature studies. The interview method is based on people's experiences and opinions. The interviewed respondents are architects and structural engineers, all of whom have worked in planning process of both concrete and wooden frames. Literature studies have contributed to a deeper understanding of the subject as well as information about the current research front. Findings: Misunderstandings in written communication and undocumented conversations are communication problems that most of the architects and structural engineers experienced. Communication problems are caused by lack of time and stress. Collaboration between the various disciplines can be adversely affected when there is no understanding of the other parties. The communication problems that have been experienced in the planning process are general and usually not affected by the choice of frame. Lack of knowledge, on the other hand, has been perceived as an additional communication problem regarding the planning process of wooden multi-storey buildings. Experience is a reason for this. Differences in communication are not affected by the choice of frame, however the communication frequency has increased. Implications: To achieve effective communication in the planning process meetings with protocol are to prefer. The lack of knowledge in the construction of high-rise buildings in wooden frames are based on the difficulty of finding experience. An increased communication frequency has been a fact because the innovation of wood frames. Future recommendations are to investigate and propose solutions to the communication problems and implement solutions to the industry. Limitations: The results of the study are limited to the architects and the structural engineers perspectives although the planning process in fact involves more parties. Collected data is based on the respondents personal opinions and experiences, therefore the results can not be determined as a general perception for all those with the same profession. Keywords: Architect, constructor, communication, planning process, wooden frame, concrete frame, communication problem, multi-storey house.

Purpose: The aim of this study is to provide improvement suggestions on how the amount of carbon dioxide emissions can be reduced in the construction of mainly multi-storey timber buildings. Proposals are made after identifying where in the life cycle the largest emissions occur. Method: To achieve the goal of this study a case study was performed on an existing multi-storey timber building. A life cycle analysis (LCA) was performed to identify where in the life cycle the biggest emissions occur. To gather all important information about the project, document analysis was conducted. In addition, a literature study was made on the subject which supports and enhances conducted study. Findings: From literature study, case study and document analysis results have been listed which forms the foundation for the following suggestions of improvement. The life cycle analysis has identified that the largest amount of carbon dioxide is 28 % and is obtained in sawmills. The production of glue produces 25 % and transports during the lifecycle produces nearly 20 %. Implications: The conclusion contributes to reducing the amount of carbon dioxide emissions in future production of mainly wooden buildings. The greatest amount of carbon dioxide have been identified and the following proposals have been made to reduce emissions. Make sawmills more effective to reduce emissions. Produce and use environmentally friendly adhesive with similar characteristics. Use waste from forest felling, sawmills and glulam factories for production of biofuel used for transports. Limitations: This study has only covered multi-storey buildings in different wooden systems, the problem is probably also relevant for other buildings. Keywords: Carbon dioxide emissions, LCA, multi-storey building, timber and wooden frame. / Syfte: Syftet med denna studie är att ge förbättringsförslag om hur mängden koldioxidutsläpp kan minskas vid byggande av främst flervåningshus i trä. Förslag tas fram efter att ha identifierat var i livscykeln de största utsläppen sker. Metod: Syftet med arbetet uppnås framförallt med en fallstudie utförd på ett existerande flervåningshus med stomme i limträ. En livscykelanalys (LCA) utfördes för att ta fram var i livscykeln de största utsläppen sker. För att samla in all viktig information om projektet utfördes även dokumentanalys. Fortsättningsvis utfördes en noggrann litteraturstudie inom ämnet som stödjer och förstärker utförd studie. Resultat: Från litteraturstudie, fallstudie och dokumentanalys har resultat tagits fram som ligger till grund för framförda förbättringsförslag. Livscykelanalysen har identifierat att den största mängden koldioxidutsläpp är 28 % och avges från sågverken. Framställandet av lim avger 25 % och transporterna under livscykeln avger ungefär 20 %. Konsekvenser: Slutsatsen bidrar till att mängden koldioxidutsläpp kan minskas i framtida produktion av framförallt byggnader i trä. Där koldioxidutsläppen är som störst i livscykeln har följande förbättringsförslag tagits fram för att minska utsläppen. Effektivisera sågverk för att minska utsläppen. Framställa och använda ett miljövänligare lim med liknande egenskaper. Utnyttja spill från skogsavverkning, sågverk och limträfabrik till att producera biobränsle som kan användas till transporter. Begränsningar: Arbetet har endast behandlat flervåningshus i olika stomsystem av trä, troligtvis är problemet aktuellt även för andra byggnader. Nyckelord: Flervåningshus, koldioxidutsläpp, LCA, limträ och trästomme.

Abstract This paper is based on interviews, a literature study and seminars. It describes the situation in Halland when it comes to multi-story housing built in timber. From 1874 to 1994, Sweden had a regulation that prohibited construction of timber houses with more than two stories as a result of big city fires. After the regulation was revoked, people started to build multi-story houses in timber again. Compared to the rest of the country there was not that many built in Halland. Construction entrepreneurs here possess the right competence and it is close to the raw material. Even though that, there are only five multi-story houses built in the county. Result from this study shows that the main problem of implementing multi-story housing built in timber is biases and lack of knowledge. Many of the players in the construction industry do not base their decisions on fact when it comes to choose timber or not. This in combination with a lack of information regarding financial issues and unfavorable regulations has resulted in a slow development of the implementation of multi-story houses. The reasons behind this are discussed in the paper and some possibilities of change are presented.

Purpose: This work has been based on getting more builders to want to build multi-storey houses with a wooden frame instead of a concrete frame. Building with various frame materials, concrete and wood, has good properties but also its challenges. On the other hand, competence and experience have a major influencing role during the production phase. This degree project has been chosen to be written by PEAB. The work focuses on and deepens itself within fire risks and moisture problems. This degree project also addresses what experience and competence look like and how they affect the production phase. Method: This work consists of literature study, case study, interviews, study visits and reference object description. Where information was taken from previous degree projects, scientific articles and research  reports. The case study that was done for this work was about two different schools, Westerlundska gymnasiet and Irstaskolan, where both are built by PEAB. There were also interviews with site managers, fire consultants and contracting engineers, where relevant questions about the subject areas fire and moisture were asked in connection with concrete frames and wooden frames. Results: Concrete as a material has good properties around fire and moisture. Concrete as a building material has long been used in the construction industry, where competence and experience are high. However, certain shortcomings in the event of a fire can occur when a multi-storey building with a concrete frame is built. Wood as a building material has other properties compared to the building material concrete. An important property of wood is that it maintains a much lower temperature on the various parts that have not caught fire yet. Conclusion: The conclusions from this project are that many construction actors choose to build with a concrete frame instead of a wooden frame. This is because experience and competence in concrete frames is greater than in wooden frames. From a fire and moisture perspective, there are challenges and solutions when it comes to concrete frames and wooden frames. It has long been built with a concrete frame, which means that more construction players have more competence and experience when it comes to concrete frames and therefore choose to work with something they are experienced with. However, there is an increased interest and construction players have an understanding that wood will be more common as a frame in multi-storey buildings in the future.

Bygg- samt fastighetsbranschen står för cirka 21% av koldioxidutsläppen i Sverige. Detta är ett problem som behöver lösas eftersom Sverige år 2017 antog ett klimatpolitiskt ramverk med målet att år 2045 inte ha några nettoutsläpp av växthusgaser till atmosfären. Ett ökat byggande i trä är en viktig del av lösningen för att nå målet om klimatneutralitet. Ett fastighetsbolag som håller på att bygga sitt första kontorshus i trä är Vasakronan, som kallas Magasin X. Det finns ett flertal utmaningar med att bygga flervåningshus i trä, dessa är bland annat fukt- och akustikproblem. Trä är ett fuktkänsligt material och om byggnaden skadas av fukt finns det en förhöjd risk för mögel som kan leda till hälsoproblem för framtida brukare av byggnaden. Gällande akustik, kan det bli lyhört, om inte hänsyn tas till materialets låga densitet. Detta examensarbete utfördes i samarbete med Vasakronan och har som syfte att identifiera drivkrafterna med att bygga flervåningshus i trä, identifiera kunskapsbrister samt identifiera förslag på lösningar inom fukt och akustik vid byggande av flervåningshus i trä. I detta examensarbete utfördes intervjuer samt observation som metoder. Observationen utfördes på en erfarenhetsträff angående byggprojektet Magasin X. Vid erfarenhetsträffen avhandlades utmaningar samt lösningar som uppkommit under projektet. Tematisk analys användes som metod för att analysera intervjuerna för att därmed besvara uppsatsens frågeställningar. Följande har identifierats som drivkrafter för att bygga flervåningshus i trä. För det första är det ett material som leder till lägre koldioxidutsläpp jämfört med betong. För det andra är det ett material som är lämpligt för industriellt byggande vilket innebär att det är lätt att tillverka byggdelar i fabrik. För det tredje är det ett material som bidrar med en bättre arbetsmiljö förde som arbetar med att uppföra byggnaden jämfört med vid uppförande av en byggnad av betong och stål. För det fjärde är det ett material som är lätt att kombinera med andra material och använda vid påbyggnader på grund av dess låga densitet. Den främsta anledningen till kunskapsbrister är begränsad erfarenhet att bygga flervåningshus i trä. Förslag på lösningar mot kunskapsbrister är att använda sig av aktiviteter som seminarium för att sprida kunskap inom ämnet, upprätta instruktioner och manualer vid användandet av nya byggmetoder. Dessutom är en lösning att bygga fler flervåningshus i trä för att ansamla erfarenhet och kunskap. Lösningar för att åtgärda fuktproblematik är att använda väderskydd på byggnaden, helklistrad plastfolie och tejp på bjälklaget samt vatten-dammsuga vid regn. Lösningar på akustikproblem är att installera installationsgolv eller installera ett tyngre övergolv med antingen betonggjutning eller spackel med stegljudsmatta. Om möjligt är väderskydd den mest effektiva åtgärden för att minska risken för fukt, dock är det en dyr lösning. Det finns dock andra åtgärder som inte är lika effektiva men billigare, som att använda plastfolie, presenningar och ställningar och tejp för att täcka bjälklag. Gällande akustiken har det dock det inte varit möjligt i denna studie att avgöra vilken akustisk lösningsom är att föredra. En drivkraft till att bygga flervåningshus i trä är att minska klimatpåverkan men för att upprätthålla ett hållbart skogsbruk är det viktigt att inte hugga ner för mycket träd. Därmed kan en hybridstomme vara ett bra alternativ för framtiden. / The construction and real estate industry accounts for a large share of carbon dioxide emissions in Sweden, about 21% of greenhouse gas emissions. This is a problem that needs to be solved because in 2017 Sweden adopted a climate policy framework with the goal that by 2045 there will be no net emissions of greenhouse gases into the atmosphere. Increased construction in wood is an important part of the solution to achieve the goal of climate neutrality. A real estate company that is building its first wooden office building is Vasakronan, which is called Magasin X. There are several challenges with building multi-storey houses in wood, these include moisture problems and acoustic problems. One factor is the risk of moisture as wood is a moisture-sensitive material and if the building is damaged by moisture, there is an increased risk of mold, which can lead to health problems for future users of the building. If the light density of the material is not considered, it might be inefficiently soundproof. This master thesis was carried out in collaboration with Vasakronan and aims to identify the driving forces in building multi-storey buildings in wood, identify lack of knowledge within building of multi-storey buildings in wood and identify and investigate solutions to solve issues with moisture and acoustics in the construction of multi-storey buildings in wood. In this thesis, interviews and observation were used as a method. The observation was carried out at an experience meeting regarding the construction project Magazine X. At the experience meeting, challenges and solutions that arose during the project were discussed. The thematic analysis was also used as a method for analyzing the interviews in order to answer the research questions. The following have been identified as driving forces for building multi-storey wooden buildings. First, it is a material that leads to lower carbon dioxide emissions compared to building in concrete. Secondly, it is a material that is suitable for industrial construction, which means that it is easy to manufacture building components in a factory. Thirdly, it is a material that contributes to a better working environment for those who work with the construction of the building compared to when constructing a building of concrete and steel. Fourth, it is a material that is easy to combine with other materials and use in extensions due to its low density. The main reason for lack of knowledge is lack of experience in building multi-storey wooden buildings. Suggestions for solutions to knowledge gaps are to use activities such as seminars to spread knowledge in the subject. Solutions to fix moisture problems are to use weather protection on the building, wet guard and tape on the framing of joists and soak up water in the risk of rain. Solutions to acoustic problems are to install installation floors or install a heavier top floor with either concrete casting or putty with sound insulation mat. If possible, weather protection is the most effective measure to reduce the risk of moisture, but it is an expensive solution. However, there are other measures that are not as effective but cheaper, such as using wet guard, tarpaulins and scaffolding and tape to cover framing of joists. It has not been possible to determine which acoustic solution is preferable. A driving force for building multi-storey wooden buildings is to reduce the climate impact, but in order to maintain sustainable forestry, it is important not to cut down too many trees. Thus, a hybrid frame can be a good alternative for the future.

Wood is a renewable material, it is strong in relation to its weight, climate smart but also combustible. Owing to its many advantages and the easy access in Sweden, wood is motivated as a topical building material. However, the aspects related to the combustible nature need to be considered in the design of buildings with a wooden frame. Whether and in such cases how to take into account the increased permanent fire load is a problem of which there are shared opinions. Today's regulatory framework is unclear in some aspects in its formulation and thus leaves room for interpretation. The purpose of this work is to investigate the reasonableness of tabulated data for permanent fire load and the sharp boundary between a BR1 building and a BR0 building but also by surveying how the industry handles the issue. In order to assess the reasonableness for the tabulated data, the method has been calculations with two different methods; one that follows BBR's guidelines (method 1) and another where calculations of the charring depth (method 2) have been performed, as well as a survey and a literature study. The result from the calculations in method 1 shows that in order for the level of the total fire load not to exceed the standard value for a residence of 800 MJ/m2, a low coefficient is required, and thus in principle all wood is assumed to be protected. According to the calculations in method two, it is possible to read out how the permanent fire load is affected by different protective linings and carbonation rates. The survey shows that the most common way to dimension fire protection is through simplified sizing, which entails that one does not have to consider whether the permanent fire load increases due to a combustible frame. There are divided opinions about whether Boverket's rules are enough to achieve adequate protection and how to handle it. The literature study shows that for the timber frame to be counted as fully protected it needs to be three layers of fire gypsum board in the ceiling and that two layers on the walls. Several conclusions can be drawn; the calculations indicate that a permanent fire load of 200 MJ/m2 (2013:11) is unreasonable in a wooden frame building also that if the permanent fire load is considered it becomes costly both economically and in terms of space. Even that Boverket's rules need to be clarified and adapted further against tall wood buildings and that fire projectors work differently and the experience of working with tall wood buildings differs greatly.

På senare tid har intresset för och viljan att bygga flerbostadshus i trä ökat och medfört en trend att bygga allt högre hus med stomme av trä. En aktör är Lindbäcks Bygg som bygger flerbostadshusi trä med volymelement och lätt regelstomme. Idag begränsas dock möjligt antal våningar med regelstomme till 6 – 8 våningar. Ett relativt nytt material inom träbyggnadstekniken är korslimmat trä (KL-trä) vars användning gjort det möjligt att bygga högre byggnader i trä. Examensarbetets syfte är att studera olika lösningar för hur Lindbäcks regelstomme kan förstärkas med KL-trä, vilket kan göra det möjligt att bygga allt högre flerbostadshus i trä. Samt att jämföra denna lösning med den idag använda regelstommen utan KL-trä. Studien har avgränsats till att enbart behandla ytterväggar. För att uppskatta rimliga laster på ytterväggar i en flervåningsbyggnad togs en principbyggnad (ihopsatt av ett antal volymelement) fram. I beräkningar tillämpades ett antal olika ytterväggstyper, en med den idag användaregelstommen (referensvägg) samt fem med regelstomme i kombination med KL-skivor i olika tjocklekar. För principbyggnaden kontrollerades genom beräkningar hur högt det är möjligt att bygga vid tillämpning av vardera ytterväggstyp. De olika ytterväggstyperna med KL-trä jämfördes även med referensytterväggen utifrån U-värde samt kostnad. Idag används KL-trä ibland av Lindbäcks och då som stabiliserande väggar. I deras fabriker tillämpas en lösning där KL-träskivorna fälls in mellan syll och hammarband tillsammans med reglarna. Beräkningar har visat att det, för principbyggnaden, med denna lösning är möjligt att bygga maximalt 2 våningar högre jämfört med referensytterväggen, detta för den bästa av ytterväggstypernaförstärkta med KL-trä. Det som begränsar ett högre antal våningar är trycket vinkelrätt fiberriktningen på syllen under KL-skivorna. Beräkningar visar att det finns en potential att med regelstomme förstärkt med KL-trä kunna bygga ännu högre om en annan lösning används där KL-träskivorna placeras på utsidan av syll, hammarband och reglar istället för infälld mellan syll och hammarband. Med denna lösning undviks tryck vinkelrätt fiberriktningen på syll under KL-skivor och KL-skivans kapacitet kan utnyttjas effektivare då normalkraftskapaciteten för själva skivan blir den begränsande faktorn för hur högt det går att bygga. Enligt beräkningar är det, för principbyggnaden, med denna lösning möjligt att bygga uppemot 8 våningar högre än med referensytterväggen. När KL-trä används i stommen ökar energiförlusterna genom väggen, dvs. U-värdet ökar, då reglar med mellanliggande isolering ersätts av KL-trä med sämre värmeledningsförmåga. Enligt beräkningar uppskattas U-värdet öka jmf. med för referensyttervägg, detta med ca. 20 – 40 % beroende på ytterväggstyp. Ökningen kan dock begränsas till ca. 0,4 – 14 % genom införande av ett 45 mm installationsskikt med isolering på väggens insida. Även kostnaden för ytterväggstyper med regelstomme förstärkt med KL-trä uppskattas öka jmf. med uppskattad kostnad för referensyttervägg. Detta med uppskattningsvis 40 – 50 %, vilket till huvudsak är en följd av ökad materialkostnad för KL-skivor som delvis ersätter reglar med mellanliggande isolering. / Today there is an increased interest in building taller buildings with timber. Lindbäcks Bygg is one of companies that uses modular construction with light timber stud frames. However, a problem with light timber frames is that the building height is limited to roughly 6 - 8 stories. A relatively new product in timber engineering is cross laminated timber (CLT) and the use of this product have made it possible to build taller timber buildings. The purpose of this study is to investigate different solutions for how Lindbäcks can strengthen their stud frames by using CLT and thereby build taller buildings. The difference with respect to U-value and cost between the walls strengthened width CLT and the typical stud frame wall, that is used today, is also studied. The study has been limited to exterior walls only. A multi-storey building consisting of several modules/volume elements has been used to estimate reasonable loads on the exterior walls. Different wall types, one with the ordinary stud frame (the reference wall) and five types of stud walls strengthened with different thicknesses of CLT, have been investigated. The maximal number of storeys that can be build, the U-value and the cost were determined by calculations for each of the studied wall types and were compared with the results for the reference wall. Today, Lindbäcks Bygg sometimes uses CLT for stabilizing walls. In their factories, they use a solution in which the CLT-plate is placed between the top and bottom plate together with the studs. According to the calculations it is, with this solution, possible to build up to 2 storeys higher then with the reference wall. The limiting factor for how high it is possible to build, is compression perpendicular to the grain on the bottom plate underneath the CLT-plate. If a solution where the CLT-plate is placed on the outside of the frame (consisting of studs, top and bottom plate) is used instead of between the top and bottom plate does the calculations show that a higher number of storeys is possible. With this solution, the compression perpendicular to the grain underneath the CLT-plate is avoided and the limiting factor is instead the compression strength of the CLT-plate. This means that the CLT can be used more efficiently. Calculations show that it is possible to build up to 8 storeys higher with this solution compared to what is possible with the reference wall. With CLT increases the energy losses through the wall, i.e. increased U-value, since studs with insulation in between is partially replaced with CLT that has worse thermal conductivity. According to the calculations, the U-value is 20 – 40 % higher (depending on the wall type) compared to the reference wall. The increase in U-value can be limited to 0.4 – 14 % by adding an extra layer with 45 mm insulation on the inside of the CLT-plate. The cost for the wall types strengthened with CLT is also higher compared to the estimated cost for the reference wall. The main reason for this is increased cost of materials since the studs with insulation in between is partially replaced with the more expensive CLT, which is an engineered wood product. The increase in cost is estimated to roughly 40 – 50 % of the cost for the reference wall.

Wood has been traditionally used as a construction material in Nordic countries such as Sweden dating back to the 12th century. Using wood as a building material for the construction of buildings with more than two stories became the norm around the 1850s and has only increased with the pressing need for more sustainable and environmentally friendly alternatives to materials such as concrete. The aim of this thesis is to bring attention to attitudes towards environmental, economic, and social sustainability of commercial multi-story wood buildings amongst industry professionals. Qualitative data was gathered through digitally conducted, semistructured interviews with six people from within fields related to carpentry, architecture, ecology, and forestry. Three buildings were briefly studied as a part of a case study on multi-story wood buildings: Fyrtornet in Malmö, Sweden, Sara  Cultural Centre in Skellefteå, Sweden, and The Oakwood Timber Tower in London, England. The results showed that the practice of constructing multi-story wood buildings wasn’t sustainable because of the intense short rotation forestry pushing ecosystems to extinction. Wood was still considered to be a good alternative to carbon intense materials such as concrete. Limitations include relying on only qualitative data as the methodology, for future research the author suggests conducting a comparative Life cycle assessment (LCA) with a cradle-to-cradle approach, as a way to study environmental impacts of timber versus other natural materials available in Sweden such as clay, straw and hemp.

This doctoral thesis concerns flanking transmission in light weight, wooden multi-storey buildings within the low frequency, primarily 20-120 Hz. The overall aim is to investigate how the finite element method can contribute in the design phase to evaluate different junctions regarding flanking transmission. Two field measurements of accelerations in light weight wooden buildings have been evaluated. In these, two sources; a stepping machine, and an electrodynamic shaker, were used. The shaker was shown to give more detailed information. However, since a light weight structure in field exhibit energy losses to surrounding building parts, reliable damping estimates were difficult to obtain. In addition, two laboratory measurements were made. These were evaluated using experimental modal analysis, giving the eigenmodes and the damping of the structures. The damping for these particular structures varies significantly with frequency, especially when an elastomer is used in the floor-wall junction. The overall damping is also higher when elastomers are used in the floor-wall junction in comparison to a screwed junction. By analysing the eigenmodes, using the modal assurance criterion, of the same structure with two types of junctions it was concluded that the modes become significantly different. Thereby the overall behavior differs. Several finite element models representing both the field and laboratory test setups have been made. The junctions between the building blocks in the models have been modeled using tie or springs and dashpots. Visual observation and the modal assurance criterion show that there is more rotational stiffness in the test structures than in the models. The findings in this doctoral thesis add understanding to how modern joints in wooden constructions can be represented by FE modelling. They will contribute in developing FE models that can be used to see the acoustic effects prior to building an entire house. However, further research is still needed. / Denna doktorsavhandling behandlar flanktransmission i flervåningshus med trästomme, inom det lågfrekventa området, främst 20-120 Hz. Det övergripande målet är att undersöka hur finita elementmetoden kan bidra i konstruktionsfasen för att utvärdera olika knutpunkters inverkan på flanktransmissionen. Två fältmätningar av accelerationer i trähus har utvärderats. I dessa har två olika lastkällor använts, i den första en stegljudsapparat och i den andra en elektrodynamisk vibrator (shaker). Det visades att shakern kan ge mer detaljerad information, men eftersom vibrationerna även sprider sig till omgivande byggnadsdelar vid fältmätningarna var det svårt att estimera tillförlitliga dämpningsdata även då shaker användes. Fältmätningarna följdes av två mätningar i laborationsmiljö. Dessa två experiment utvärderades med experimentell modalanalys, vilket ger egenmoder och dämpning hos strukturerna. Dämpningen för dessa trähuskonstruktioner varierar kraftigt med frekvens. Extra stora variationer registreras då en elastomer användes i knutpunkten mellan golv och vägg. Den totala dämpningen är generellt högre när elastomerer används i knutpunkten mellan golv och vägg i jämförelse med då knutpunkten är skruvad. Genom att analysera egenmoder och deras korrelationer (MAC), för samma trästruktur men med olika typer av knutpunkter, drogs slutsatsen att knutpunkten drastiskt förändrar strukturens dynamiska beteende. Flera finita elementmodeller av både fält- och laboratorieuppställningar har gjorts. I dessa har knutpunkterna mellan byggnadsdelar modellerats helt styvt eller med hjälp av fjädrar och dämpare. Visuella observationer av egenmoder och korrelationen dem emellan visar att det finns mer rotationsstyvhet i försöken än i finita elementmodellerna. Resultaten i denna doktorsavhandling har gett förståelse för hur knutpunkter i träkonstruktioner beter sig och kan simuleras med finit elementmodellering. Vidare kan resultaten bidra till utvecklingen av FE-modeller som kan användas för att kunna se de akustiska effekterna redan under konstruktionsstadiet. Dock behövs ytterligare forskning inom området.

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