I takt med en ökad miljömedvetenhet har träbyggnation börjat premieras allt mer och sedan lagändringen 1994 som innebar att det blev tillåtet att uppföra höga hus med trästomme har utvecklingen snabbt gått framåt. Att korsvis bygga upp skikt av brädor och sammanfoga dessa till element har visat sig skapa en produkt med hög hållfasthet och låg vikt som är idealisk som stommaterial vid byggnation av stora och höga hus i trä. Dessa element har många namn men kallas ofta korslimmat trä och kommer i arbetet benämnas CLT, cross-laminated timber. Dess användning har ökat markant i Sverige och Europa de senaste decennierna och än ses ingen stagnation på efterfrågan.   Denna rapport behandlar relevanta teoretiska områden som måste tas i beaktning vid branddimensionering som exempelvis brandförloppet i en brandcell samt hur brandsäkerhetsklasser och brandtekniska byggnadsklasser bestäms och fastställs. Dimensioneringsmetoder av laster och hållfasthet i både brottgräns och i brandfallet förklaras genomgående för skapa en tydlig bild av hela branddimensioneringsprocessen. Brist på direkt information om hur hållfastheten av resttvärsnitten ska behandlas och beräknas har gjort arbetet utmanande men med hjälp från Maija Tiainen från Sweco structures Helsingforskontor har arbetet kunnat färdigställas och bli fullständigt.   Den viktigaste delen i rapporten är dock själva inbränningen och förkolningen av elementen som beräknas med hjälp av två olika metoder. Den ena återfinns i den europeiska standarden Eurokod 5: del 1-2 och den andra, som baseras på den absolut senaste forskningen gällande träkonstruktioner och brand, är hämtad från handboken Brandsäkra trähus version 3. Den senare metoden kommer ligga till grund för en uppdatering av Eurokod 5 i framtiden.   För att kunna jämföra de två metoderna och ge en nyanserad bild av dessa valdes fyra väggtyper ut som beräknades med samma förutsättningar. Det vill säga skyddade med två lager gips och utsatta för en 90 minuters ensidig standardbrand.   Resultatet visade på skillnader mellan metoderna där en tydlig och definitiv sådan var storleken på resttvärsnittet då det icke lastupptagande skiktet, , visade sig vara mycket större i beräkningarna enligt metoden i Brandsäkra trähus version 3. På grund av elementens uppbyggnad, korsvis lagda skikt där endast vartannat skikt är lastbärande, betyder detta inte nödvändigtvis att det resulterar i en skillnad gällande bärförmåga i brandfallet mellan de två metoderna.   Trots att metoden i Brandsäkra trähus version 3 är mer konservativ gällande bärförmåga och leder till ett mindre resttvärsnitt efter brand anser författarna att denna metod bör användas i väntan på en inarbetning av metoden i Eurokoden. Detta då den till skillnad från Eurokoden är utformad och framtagen för att kunna behandla CLT och då säkerheten är viktigast i sammanhanget måste brandens ökade påverkan på materialet enligt den senaste forskningen tas på allvar och tvärsnittet dimensioneras därefter. / In recent years, a growing environmental awareness have led to an increase in timber buildings and since the 1994 amendment that made it possible to build tall houses with timber structures the progress in the field have seen an substantial increase. To build an element of perpendicularly placed layers of solid-sawn lumber have proven to be an effective way to obtain a product with good strength-to-weight ratio that is ideal for use in tall timber buildings. These elements go under a lot of different names but are often referred to as cross-laminated timber and will be called CLT in this report. The use of this product have these past decades increased substantially both in Sweden and in Europe and the demand does not seem to stagnate nor decrease in the near future.   The report is comprised of relevant theoretical sections that must be taken into account when designing a structures fire protection such as the development of a fire in fire compartment, how to define and determine a structures class of fire resistance and hence required fire protection time for said structure. The basis of design in regards to loads and compressive/flexural strength of the material is thoroughly explained in order to account for the whole fire protection design processes. The lack of information regarding compressive and flexural strength of the residual cross-section was challenging but with the help from Maija Tiainen from Sweco structures Helsinki office the report could be completed.   The most important part of the report is the theory and calculation with regards to the charring depth which is calculated by two different methods. The first one is presented in the European standard Eurocode 5: part 1-2 and the other one, that is based on the latest scientific knowledge with regards to timber structures and fire, is found in the technical guide Brandsäkra trähus version 3. The aforementioned method will form the basis for the upcoming update of Eurocode 5.   In order to be able to compare the two methods four wall types was chosen and designed based on the same conditions. Namely protected by two layers of gypsum plasterboards as fire protection and exposed to a 90 minutes one-sided standard fire.   The result showed differences between the methods where a clear difference was the size of the residual cross-section due to the fact that the zero-strength layer, , was notably larger when calculating with the method presented in Brandsäkra trähus version 3. This does not necessarily affect the elements bearing capacity when calculating with the two different methods due to the elements perpendicularly placed layers where only every other layer is load bearing.   Although the method presented in Brandsäkra trähus version 3 are more conservative with regards to bearing capacity and will lead to a smaller residual cross-section the authors of this report recommend the use of said method pending incorporation into the Eurocode. The motivation for this suggestion is that the method is designed to explicitly handle CLT and since safety is the most important aspect in this context it is vital to acknowledge the apparent increased affect from a fire on the material according to the latest scientific knowledge and design the cross-section accordingly.

The goal of this study was to assess the potential of using hardwood lumber in CLT manufacturing. The goal was achieved by addressing four specific objectives. The first objective was to collect CLT manufacturers' perspectives for using hardwood lumber in the current manufacturing setup. The second objective was to determine hardwood sawmills' current ability to produce structural grade lumber (SGHL) from low value logs as a product mix through a survey of hardwood lumber producers in the US. The third objective was to conduct a log yield study of SGHL production from yellow poplar (YP) logs to produce 6'' and 8'' width SGHL to match the PRG 320 requirements. The fourth objective was to determine CLTs' production cost using SGHL and compared it with the CLTs manufactured from southern yellow pine (SYP). The results suggest that all three CLT industries visited and interviewed had sufficient technology to produce hardwood CLTs. The production of hardwood CLTs was mainly limited by the quality and quantity of lumber available. The hardwood sawmill survey results indicated that, currently, less than 10% of the sawmills had all the resources required to produce SGHL. The current ability of the sawmills was measured based on the resources necessary to begin SGHL production. Forty percent of the sawmills would require an investment in sawing technology to saw SGHL, 70% would require employing a certified lumber grader, and 80% would require a planer to surface lumber. Another significant finding was the sawmills' willingness to collaborate with other sawmills and lumber manufacturers. More than 50% of sawmills were open to potential collaboration with other stakeholders if necessary, which is crucial to commercializing SGHL for a new market. The log yield study of yellow poplar helped demonstrate that the mixed grade lumber production method to convert lumber from lower quality zones as SGHL yields higher lumber volume for sawmills and at the same time reduces lower-grade lumber volume. On average, SGHL production increased lumber volume by more than 6% compared to only NHLA grade lumber production when 65% of the lumber was converted to SGHL. The volume of lower lumber grades from 2 common and below decreased from an average of 85% to less than 30% when producing SGHL as a product mix with NHLA grade lumber. This study observed more than 95% of SGHL as Number 3 and better lumber grades. At estimated lumber value, 2x6 and 2x8 SGHL and NHLA grade lumber production as product mix from a log generate higher revenue for all log groups except for the diameter 13" logs. A lower percentage of higher-grade lumber was observed for diameter 13’’ logs than other log groups from this experiment, which resulted in lower revenue. Production cost of CLTs was determined based on the lumber value to manufacture 40' x 10' plain panels with different combinations by lumber grade of yellow poplar and southern yellow pine lumber alone. Production cost was determined by assuming that lumber value contributes 40% of CLTs' total production cost. The 3- ply CLT panels were manufactured using S. Selects lumber in a major direction, and No 1-grade lumber in the minor direction from YP had a production cost of $662.56 per cubic meter, which cost only $643.10 when SYP lumber was used at referenced lumber value. This study concludes that CLT panels from YP cost 3-7 % more than SYP-CLTs at the referenced lumber values. / Ph.D. / This research aims to expand the hardwood lumber consumption in the US by evaluating the opportunity to manufacture cross-laminated timber (CLTs). First, CLT manufacturing industries were visited to know their current capacity to process hardwood lumber. The results suggest that all three CLT industries had sufficient technology to produce hardwood CLTs, and the production was mainly limited by the quality and quantity of lumber available. Commercially hardwood can be used in CLT manufacturing if it can be used for structural application. Hardwood lumber must meet the structural application's minimum requirements to manufacture the structural grade CLTs, so we surveyed the hardwood sawmills to know if they have the required resources to manufacture the structural grade hardwood lumber (SGHL). Only ten percent of the sawmills had required technology to produce SGHL without additional investments. Production of the SGHL also required to generate more revenue for the hardwood sawmills, so we conducted the log yield study to know how the revenue structure of sawmill operation will change from the mixed grade lumber production. At estimated lumber value, 2x6 and 2x8 SGHL and 1-inch National Hardwood Lumber Association (NHLA) grade lumber production as product mix from logs generate higher revenue for all log groups except for the diameter 13" logs. Finally, the production cost of SGHL from the log yield study was evaluated and used to produce CLTs at 40% production cost from lumber at 15% profit margins for sawmills and compare with southern yellow pines CLTs. The results indicate that yellow poplar CLTs cost 3-7 % more than southern yellow pines CLTs at the referenced lumber values. This study concludes that hardwood lumber can be used in CLT manufacturing, so there is an opportunity for hardwood sawmills to expand the market. The first step for commercial production of hardwood CLTs is to produce SGHL on a commercial scale, given that sawmills can benefit from these new products in the current lumber market and meet the minimum requirements of the CLT raw materials.

Introduktion – Byggbranschen idag står för en betydande andel av jordensväxthusgasutsläpp och behovet för att minska dessa är stora. Att investera merklimatsmart i nybyggnation ökar och trä har blivit till ett alltmer populärt byggmaterialnär det kommer till flerbostadshus, men logistikhallar domineras fortfarande av stål.Studiens mål är att undersöka skillnaderna i kostnader och utsläpp av växthusgasermellan limträ- och stålstommar för logistikhallar. Detta för att undersöka om trä är ettekonomiskt rimligt och mer miljöeffektivt stommaterial vid byggnation avlogistikhallar än en stålstomme. Metod – Metoden som valts till studien är en fallstudie då den kommer omfatta bådeen teoretisk undersökning, granskning av kvantitativa data från ett tidigare projekt samtuppskatta storleken på en trästommes tvärsnitt genom simulering i endimensioneringsmjukvara. Kostnad och miljöpåverkan för en stål- och limträstommekommer att tas fram för att sedan kunna utföra en jämförande analys av de tvåstommaterialen. Resultat – Stommarna skiljer sig procentuellt sätt inte så mycket i pris menlimträstommen orsakar betydligt mindre växthusgasutsläpp jämfört med stålstommen.Kostnaden mellan stål- och trästommen skiljde sig knappt utifrån material- ochmontagekostnaderna. Stålstommen står för nästan sju gånger mer växthusgasutsläpp änlimträstommen under produktionsstadiet. I transportskedet har limträ en längretransportsträcka än stål i denna studie vilket är huvudorsaken till att limträstommenspåverkan på miljön är större än stålstommen i detta skede. Monteringsskedet harstålstommen en större miljöpåverkan än trästommen. Utifrån hela stommen under helabygg- och produktionsstadiet hade stålstommen fyra gånger mer i utsläpp änlimträstommen. Analys – Om priset på stommen är det huvudsakliga intresset hos byggherren bör inteen stålstomme antas vara det billigare alternativet. Denna studie har största spännvidderav balkar på 24 meter och vid större spännvidder kan förutsättningarna för val avstommaterial se annorlunda ut. Limträ är väl lämpat som stommaterial om ambitionenär att bygga med små mängder växthusgasutsläpp. Diskussion – Byggbranschen har en viktig roll i arbetet med att minskakoldioxidutsläppen och uppnå klimatmålen. Trots att trästommen som analyserats inteär optimalt utformad påvisar ändå studien stora miljömässiga fördelar att användalimträ som stommaterial i logistikhallar utan några större skillnader i kostnad. / Introduction – The construction industry today accounts for a significant portion ofthe Earth's greenhouse gas emissions, and the need to reduce these emissions issubstantial. Investing more climate-smartly in new construction is increasing, and woodhas become an increasingly popular building material, especially for multi-familyhouses. However, logistic warehouses are still predominantly dominated by steel. Theaim of this study is to investigate the differences in costs and greenhouse gas emissionsbetween glulam timber and steel frames for logistic warehouses. This is done toexamine whether wood is an economically viable and environmentally more efficientstructural material for constructing logistic warehouses compared to a steel frame. Method – The chosen method for the study is a case study, as it will encompass both atheoretical examination, a review of quantitative data from a previous project, and anestimation of the cross-sectional size of a timber frame through simulation in astructural design software. The cost and environmental impact of a steel and glulamtimber frame will be determined in order to conduct a comparative analysis of the twostructural materials. Results – The frames do not differ significantly in terms of price, but the glulam timberframe results in significantly lower greenhouse gas emissions compared to the steelframe. The cost difference between steel and timber frames was minimal based onmaterial and assembly costs. The steel frame generates almost seven times moregreenhouse gas emissions than the glulam timber frame during the production stage. Inthe transportation phase, laminated timber has a longer transportation distance then steelin this study, which is the main reason for the greater environmental impact of thelaminated timber frame compared to the steel frame at this stage. During the assemblyphase, the steel frame has a larger environmental impact than the timber frame. Acrossthe entire frame during the entire construction and production stages, the steel framehas four times more emissions than the glulam timber frame. Analysis – If the cost of the frame is the primary concern for the builder, a steel frameshould not be assumed to be the cheaper alternative. This study considers the widestspan of beams at 24 meters, and for larger spans, the conditions for choosing structuralmaterials might differ. Glulam timber is well-suited as a structural material if the goalis to build with minimal greenhouse gas emissions. Discussion – The construction industry plays a crucial role in reducing carbon dioxideemissions and achieving climate goals. Despite the fact that the analyzed timber framemight not be optimally designed, the study still demonstrates significant environmentaladvantages in using glulam timber as a structural material in logistic warehouses, withno major differences in cost.

Träbyggandet har ökat drastiskt sedan år 1994 då den Europeiska unionen (EU) införskaffade ett byggproduktdirektiv, idag numera ersatt med byggproduktförordningen CPR, Construction Products Regulation. Från att träbyggandet tidigare främst inkluderat bostadsbyggande kan nu även föreskrivna funktioner godkännas för högre byggnader. Trämaterialets förmåga att binda koldioxid och utveckling av korslimmat trä, förkortat KL-trä, är två bidragande faktorer till att trä idag är ett uppmärksammat byggmaterial. Mer användning av trä i höga byggnader kan dock, på grund av dess låga vikt och styvhet, medföra känsligheter mot dynamisk vindpåverkan vilket kan vara en avgörande faktor vid dimensionering. Förhöjda accelerationsnivåer är en konsekvens av de dynamiska lasterna vilket som påföljd kan ha en negativ effekt på brukarna av byggnaden. I följande examensarbete studeras denna problematik för en standardiserad byggnad. Syftet med examensarbete är att undersöka hur implementering och användning av trä i en hög byggnad påverkar byggnadens dynamiska respons och koldioxidutsläpp. Studien fokuserar på att undersöka hur accelerationsnivåerna ser ut vid användning av konstruktionssystem som är helt eller delvis av trä samt vilket förändrat klimatavtryck detta medför jämfört med en standardiserad betongbyggnad. I första delen av fallstudien studeras accelerationsnivåerna för olika alternativa konstruktionssystem där majoriteten av stabiliseringen nyttjas genom stabiliserande skivor internt och externt i byggnaden. I fallstudiens andra del används resultaten från första delen för att iterativt skapa en modell med lägst möjliga koldioxidavtryck och som samtidigt uppfyller acceptabla accelerationsnivåer enligt ISO 10137. De studerade strukturerna modelleras upp i Finita Element programvaran FEM-Design 20 utifrån en framtagen grundmodell baserad på tidigare litteraturstudie. I programvaran utförs en modalanalys för att erhålla egenfrekvenser och svängningsmoder för de studerade strukturerna. Med dessa ingångsvärden beräknas accelerationsnivåerna för samtliga strukturer enligt riktlinjer i EKS11 och SS-EN 1991-1-4 samt jämförs med acceptabla accelerationsnivåer i ISO 10137. Med erhållna resultat används en iterativ process för att ta fram en struktur med minsta möjliga koldioxidavtryck. Klimatavtrycket jämförs med den standardiserade betongbyggnaden genom att beräkna och jämföra mängden koldioxidekvivalenter.  Resultatet visar att det är mest fördelaktigt att nyttja intern stabilisering för att erhålla högre egenfrekvenser och lägre accelerationsnivåer. Strukturer som nyttjar extern stabilisering visar förhöjda accelerationsnivåer med   jämfört med intern stabilisering. Dock visar användning av intern stabilisering att det är större sannolikhet att erhålla roterande svängningar som första svängningsmod, detta innebär att de stabiliserande väggarna bör adderas till strukturen med försiktighet. Användning av kombinerad intern- och extern stabilisering visar ingen påtaglig fördel, dock visar resultatet att sammanhängande skivor som bildar en stabiliserande kärna bidrar till en markant ökning i byggnadens styvhet. Den modell som tagits fram med minst klimatavtryck har ett pelar-balksystem i limträ med KL-träskivor i bjälklag och som stabilisering i byggnadens centrala delar. Beräkning av byggnadernas koldioxidavtryck visar en reduktion på  , störst reduktion fås för bjälklagen. / Since year 1994, timber construction has increased dramatically due to that the European Union (EU) acquired a construction product directive, later replaced by the Construction Products Regulation (CPR). Timber construction has previously mainly included housing construction but is nowadays also used for high-rise buildings, this due to that the prescribed properties now can be approved for taller buildings. Two contributing factors to making timber a popular building material is its ability to bind carbon dioxide and the development of cross-laminated timber. On the other hand, using more timber in high-rise buildings can lead to sensitivities to dynamic wind loading due to its low weight and stiffness. This can be a decisive factor during design. Increased acceleration levels are a consequence of the dynamic loading which can have a negative effect on the users of the building. In following thesis this problem is studied for a standardized building. The purpose of the thesis is to investigate how implementation and the use of timber in high-rise buildings affects the building’s dynamic response and carbon dioxide emissions. The main focus is to study how the acceleration levels vary when using construction systems entirely or partly of timber and what carbon footprint this entails, compared to a standardized concrete building. In the first part of the case study, the acceleration levels for different construction systems are studied, where the majority of the stabilization is used internally and externally in the building. In the second part of the case study, the results from the first part are used to iteratively produce a model that have the lowest possible carbon footprint, as well as acceptable requirements regarding acceleration levels is achieved according to ISO 10137. The studied structures are modeled in the Finite Element software FEM-Design 20 based on a base model from a literature study. A modal analysis is performed in the software to obtain natural frequencies and mode shapes for the studied structures. With these input values, the acceleration levels can be calculated according to the guidelines in EKS 11 and SS-EN 1991-1-4, and then compared with acceptable acceleration levels in ISO 10137. With the results obtained, an iterative process is used to make a model with lowest possible carbon footprint. Lastly, the carbon footprint is compared with the standardized concrete building by calculating and comparing the amount of carbon dioxide equivalents.  The results show that it is most beneficial to use internal stabilization in order to obtain higher natural frequencies and lower acceleration levels. Structures using external stabilization show increased acceleration levels by   compared to internal stabilization. However, the use of internal stabilization shows that rotational mode shapes are more likely to be obtained as the first mode shape, this means that the stabilizing walls should be added to the structure with caution. The use of a combination of both internal and external stabilization shows no significant improvements. However, the results show that continuous walls forming a central core contributes to a significant increased stiffness for the structure, compared to separately placed walls. The final model with the lowest possible carbon footprint has a column-beam system in glulam with cross-laminated timber in the floors, and as stabilization in the central parts of the building (core). Calculation of the building’s carbon footprint shows a reduction of  , the largest reduction is achieved in the floors.

This thesis is mainly focused on the seismic behaviour of cross laminated timber (CLT) buildings. The document can be subdivided into three main sections closely related to each other. In the first part, after a short introduction on the state of the art on timber buildings regarding the constructive and legislative issues, the behaviour of CLT buildings is presented. The research is focused on the study on single shear-walls, on the multi-storey single-walls and on the behaviour of the whole buildings. The analyses are performed in order to assess the ductility level achievable by a CLT building as a result of different choices for the ductility of the connections at the foundation level. In order to estimate the ductility level, a large number of non-linear analyses were performed. This was possible thanks to a Matlab code, specifically developed, which allowed to reduce the computational burden. The results are used to evaluate a reliable set of behaviour factors to be applied in the seismic design of CLT buildings. In the second part of thesis, the low-cyclic fatigue strengths for different typologies of dissipative timber connections are presented. The low-cyclic fatigue strength represents a key-parameter in the assessment of the seismic behaviour of timber connections. In fact, high values of ductility associated with low values of strength degradation ensure a remarkable and reliable energy dissipation without a significant loss of strength. Despite the current version of chapter 8 of Eurocode 8 requires specific values of seismic demand for timber connections in terms of low-cyclic fatigue strength, no specific provision is reported to this regard in the European Standard for the cycling testing of timber connections and assemblage in seismic design (EN 12512). In This Standard the ductility capacity and the impairment of strength are calculated as separate mechanical parameters. For this reason, a proposal of revision of European Standard EN12512 is presented and discussed. The third and last part of the thesis describes an innovative connection for CLT buildings. This innovative connection was originally developed in order to absorb both traction and shear actions. Furthermore, a good performance has been obtained in terms of low-cyclic fatigue strength and ductility, with the aim of conceiving a connection able of satisfy the requirements of the current seismic European Standard. The design of this new connection was an iterative process, starting from some simplified numerical models. After some improvements, it was possible to obtain the expected performance levels. The strength and rigidity of the designed connection were initially obtained through numerical analysis, and then compared with the results of physical tests carried out in the Materials and Structures Testing Laboratory (MSTL), that is a part of the Department of Civil, Environmental and Mechanical Engineering (DICAM) of the University of Trento.

The background to the study is the construction industry's global environmental impact. In this study, it is investigated whether CLT (cross laminated timber) and sheep wool insulation is a building technology alternative in an exterior wall based on today’s building standards. To find out if CLT and sheep wool insulation are an alternative for an external wall construction, a literature study and hand calculations were carried out. The literature study summarizes regulations from Boverket BFS 2020:4 regarding moisture, fire, energy and sound requirements. In order to assess how an external wall made of CLT and sheep wool insulation works, three different external wall constructions were developed. Hand calculations were used to determine the heat transfer coefficient and relative vapor of the wall proposals. The results from the calculations show that all wall proposals work with regard to moisture and thermal comfort. Both sheep wool and CLT have a high specific heat capacity, but the volumetric heat capacity and the location of the material determines whether it affects the indoor environment. The study shows that the fire properties of sheep wool mean that the placement of the sheep wool insulation is decisive for whether the wall will be fireproof or not. Calculations of penetration depth in case of fire for CLT show that CLT is a suitable material from a fire point of view. The design flexibility of CLT means that the construction can be adapted so that the sound insulation requirements are met for buildings with special requirements. 54% of the sheep wool produced in Sweden is discarded, according to calculations, the discarded sheep wool can insulate external walls for approx. 11% of the detached houses produced annually. A study was conducted on whether wool can cause allergies, the information does not indicate that sheep wool insulation can cause allergies. The study concludes that combining sheep wool insulation with CLT is possible however the use of CLT is more justified in a multi-storey house than a single-family house. / Bakgrunden till studien är byggbranschens globala miljöpåverkan. I den här studien utreds det om KL-trä (korslimmat trä) och fårullsisolering är ett byggnadstekniskt alternativ i en yttervägg utifrån dagens byggnadsstandard. För att ta reda på om KL-trä och fårullsisolering är ett alternativ för en ytterväggskonstruktion genomfördes en litteraturstudie och handberäkningar. Litteraturstudien sammanfattar föreskrifter från Boverkets byggregler BFS 2020:4 gällande fukt-, brand-, energi- och ljudkrav. För att bedöma hur en yttervägg uppbyggd av KL-trä och fårullsisolering fungerar togs tre olika ytterväggskonstruktioner fram. Med handberäkningar bestämdes väggförslagens värmegenomgångskoefficient och relativa ånghalt. Resultatet från beräkningarna visar att samtliga väggförslag fungerar med avseende på fukt och termisk komfort. Både fårull och KL-trä har hög specifik värmekapacitet men materialets volymetriska värmekapacitet och placering avgör om den påverkar inomhusmiljön. Studien visar att fårullens brandegenskaper gör att placeringen av fårullsisoleringen är avgörande för om väggen blir brandsäker eller inte. Beräkningar av inträngningsdjup vid brand för KL-trä visar att KL-trä är ett lämpligt material ur brandsynpunkt. Designflexibliteten hos KL-trä gör att konstruktionen kan anpassas så att ljudisoleringskraven uppnås för byggnader med särskilda krav. 54% av den i Sverige producerade fårullen kasseras, enligt beräkningar kan den kasserade fårullen isolera ytterväggar i ca. 11% av småhusen som produceras årligen. Det gjordes en undersökning om ull kan framkalla allergi, informationen tyder inte på att fårullsisolering kan orsaka allergi.  Studien kommer fram till att kombinera fårullsisolering med KL-trä är möjligt och att användande av KL-trä är mer motiverat i ett flervåningshus än ett småhus.

Housing in prosperous American cities is becoming increasingly expensive, forcing many municipal governments to re-evaluate how they will continue to serve lower-income residents and ensure equitable access to housing and resources. In the City of Alexandria, the Alexandria Re-Development and Housing Authority (ARHA) has worked in recent years to partner with private developers to convert its existing stock of low-density, designated-affordable housing into more dense, mixed-income communities. This is possible because many of its existing communities sit on land in now-prime locations where the City currently allows the most density, as well as bonus density through a variety of mechanisms. While these projects have succeeded to some extent, the City is unfortunately still seeing a rapid rise in rents accompanied by a rapid decrease in available affordable housing of all types, in both privately-developed and publicly-subsidized communities. Increasing income disparity is also simultaneously driving lower-income to middle-class residents to suburban and exurban sites where limited access to municipal resources and public transportation can be highly detrimental to quality of life. While additional density is the knee-jerk response to many of affordability's challenges, often the resulting built solutions seem incomplete – achieving the basic goal of housing more residents, but failing to build thriving and diverse communities that connect people the way previous communities may have. After all, the pragmatics of building generally point towards maximizing square footage, monetary return, and speed of delivery by using conventional and commonly-accepted solutions, with less energy given to resident outcomes, and how people might be affected by the change to their living environments and communities. As Jan Gehl and Jane Jacobs examined in Cities for People and The Death and Life of Great American Cities respectively, simple pragmatics do not make for livable environments. A truly humanist approach to design for living in cities requires not only good policy, practice, and engagement, but also architectural strategies that respond to how humans relate to each other and their surroundings. Convergence explores how designers can contribute to making urban housing better for everyone by addressing housing affordability, person-to-person interaction, and community engagement in increasingly-dense environments. Its primary objectives are: • Encouraging neighborliness by increasing chance encounters as well as reducing the sharp threshold between private and public space often found in apartment-style buildings. • Increasing the visibility of human activity to the street in a multi-floor, multi-family project. • Using new mass timber methods and modularity to improve initial building construction and cost while also incorporating sustainable practices to reduce resource use and operating cost. • Anticipating that modification and reconfiguration will be required in the future, and offering defined parameters to simplify that process. • Creating a variety of unit sizes while also offering future flexibility to respond to changing community needs. • Combining the familiar with the novel to connect the new community to its surroundings, bridge experiences, and manage change. / Master of Architecture / In the City of Alexandria, the Alexandria Re-Development and Housing Authority (ARHA) owns several affordable housing sites in desirable locations that it has been working to convert into more dense, mixed-income housing in partnership with private developers. While these projects have succeeded to some extent, housing in the City continues to become increasingly expensive, and wages for low-income and lower-middle class residents are not keeping pace with the increase in cost of living. This phenomenon is pushing many long-time and/or lower-wage residents to the suburbs and exurbs, limiting access to municipal resources and public transportation, and reducing quality of life. As a result, communities and families with long histories in the City are breaking apart and dispersing. Many advocates, policymakers, designers, and developers have turned to additional density as the most immediate response to these concerns. However, additional density isn’t enough; new buildings may house more people, but fail to address the other aspects of building thriving and diverse communities that connect people the way previous communities may have. Good housing and good communities need more than square footage, so it is time to look beyond conventional solutions. New approaches are needed to respond to how people are affected by changes to their living environments and communities, and create the kinds of positive outcomes that should be part of any new housing project. Therefore, if we want to design for living in cities, we have to have good policies, practices, and engagement, but we also need architectural strategies that respond to how humans relate to each other and their surroundings. Convergence explores how designers can contribute to making urban housing better for everyone by addressing housing affordability, person-to-person interaction, and community engagement in increasingly-dense environments. Its primary objectives are: • Encouraging neighborliness by increasing chance encounters as well as reducing the sharp threshold between private and public space often found in apartment-style buildings. • Increasing the visibility of human activity to the street in a multi-floor, multi-family project. • Using new mass timber methods and modularity to improve initial building construction and cost while also incorporating sustainable practices to reduce resource use and operating cost. • Anticipating that modification and reconfiguration will be required in the future, and offering defined parameters to simplify that process. • Creating a variety of unit sizes while also offering future flexibility to respond to changing community needs. • Combining the familiar with the novel to connect the new community to its surroundings, bridge experiences, and manage change.

Att bygga bjälklag av massivt trä blir allt vanligare och är ett sätt att minska klimatavtrycket från byggbranschen. Korslimmat trä, även kallat KL-trä, står för lejonparten av dessa massiva träbjälklag. Ett mindre vanligt alternativ till KL-trä är brädstapelbjälklag. Fördelen med brädstapelbjälklag är att fiberriktningen på virket går i samma riktning. Detta ger en något högre styvhet så man kan bygga lägre moduler med mindre virke och således spara på trä och dessutom slippa användningen av lim. Om man därutöver kan sätta ihop modulerna på plats slipper man tunga transporter och industriell tillverkning. En nackdel med brädstapelbjälklag är att man historiskt har använt spikar av metall som både går emot principen att bygga med enbart trä och dessutom försvårar möjligheter till återbruk av trämaterialet. LignoLoc är en spik tillverkad av densifierat bokträ och en relativt ny produkt på marknaden. Spiken skjuts in i virket med tryckluft och friktionen får ligninet i spiken att delvis smälta ihop med det omgivande virket. Svetseffekten tillsammans med det densifierade trämaterialet ger relativt goda hållfasthetsvärden, speciellt vid dragbelastning. I detta examensarbete undersöks hur man kan bygga brädstapelbjälklag med LignoLoc spik som uppfyller gällande brukskrav för nedböjning och vibration samt för brand. Undersökningen utgår ifrån befintlig teori för konstruktion av brädstapelbjälklag med trådspik och kombineras med studier kring LignoLoc spikens uppmätta egenskaper och tillämpade beräkningsmodeller. Med detta som grund görs en ansats till en generell beräkningsmodell för konstruktion av brädstapelbjälklag med LignoLoc spik. För att befästa ansatsen utförs även en praktisk hållfasthetsstudie i en storskalig modell där tre olika moduler belastningstestas i en hydraulisk press. Slutsatsen är att de tillämpade beräkningsmodellerna stämmer väl överens med utfallen från de praktiska belastningstesterna. Testerna tyder på att LignoLoc spiken håller långt över förväntan för skjuvbrott och ger en marginellt styvare konstruktion än motsvarande med trådspik. Vidare kan konstateras att LignoLoc spiken fungerar gott som alternativ till trådspik. Således kan man bygga brädstapelbjälklag i 100% trämaterial som ett alternativ till KL-trä. / Building floors from solid wood is becoming increasingly common and is a way to reduce the environmental footprint of the construction industry. Cross-laminated timber, also known as CLT, accounts for the majority of these solid wood floors. A less common alternative to CLT is Nail Laminated Timber (NLT). The advantage of NLT is that the grain direction of the timber runs in the same direction. This gives slightly higher stiffness, allowing for the construction of thinner modules with less timber, thus saving on wood and eliminating the need for glue. Additionally, if the modules can be assembled on-site, heavy transportation and industrial manufacturing can be avoided. However, the downside of NLT is that historically, metal nails have been used, which contradicts the principle of building with solid wood and also complicates the reuse of the timber material. LignoLoc is a nail made of densified beech wood and is a relatively new product on the market. The nail is driven into the wood with compressed air, and the friction causes the lignin in the nail to partially melt and fuse with the surrounding wood. This welding effect, combined with the densified wood material, provides relatively good strength values, especially under tensile load. This thesis investigates how to build NLT with LignoLoc nails that meet current serviceability requirements for deflection, fire, and vibration effects. Starting from existing theory for the construction of NLT with metal nails and combining it with studies on the measured properties of LignoLoc nails and applied calculation models, an approach is made to a general calculation model for the construction of NLT with LignoLoc nails. To validate the approach, a practical strength study is also carried out on a large-scale model where three different modules are load-tested in a hydraulic press. The conclusion is that the applied calculation models match well with the outcomes of the practical load tests. The tests indicate that the LignoLoc nail far exceeds expectations for shear failure and provides a marginally stiffer construction than the equivalent with steel nails. Furthermore, it can be stated that the LignoLoc nail works well as an alternative to steel nails. Thus, it is possible to build NLT in 100% wood material as an alternative to CLT.

Master thesis is focused to design the timber pedestrian bridge over the track. The load-bearing construction is composed from the truss girder and cross laminated tiber plates. Bridge is coveder. Layout dimensions of the bridge are 49.0 m x 4.8 m

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.