Painéis de Cross Laminated Timber (CLT) consistem em um elemento construtivo relativamente novo no cenário da construção civil internacional. No Brasil, a fabricação desta tecnologia iniciou-se há cerca de seis anos. Em razão de sua incipiente utilização em território nacional, não se formou ainda bibliografia consistente a seu respeito, suscitando questionamentos sobre o desempenho dos painéis ao longo da vida útil da edificação. Deve-se ressaltar também que o elemento construtivo estudado consiste em uma inovação, associada à pré-fabricação e a técnicas de fabricação digital, diferenciando-se das tecnologias convencionais com as quais arquitetos e projetistas estão acostumados a projetar. Consequentemente, observam-se frequentes dúvidas não apenas sobre o desempenho dos painéis, mas também associadas a como projetar, de forma eficaz e apropriada, um edifício em CLT. Logo, surge o interesse em aprofundar os estudos acerca da tecnologia, com o intuito de propor, ao final da pesquisa, recomendações para projetos arquitetônicos que visem incorporar painéis de CLT de produção brasileira. Dessa forma, estudou-se tanto o desempenho do elemento construtivo, no que diz respeito à segurança estrutural e à durabilidade, conforme a ABNT NBR 15575:2013, quanto o processo construtivo de edificações em CLT. Para a análise de desempenho mencionada foram realizados os seguintes ensaios laboratoriais: retenção e penetração do produto preservativo na matéria-prima utilizada para a fabricação dos painéis nacionais; impacto de corpo mole, impacto de corpo duro e determinação da resistência do painel às solicitações de peças suspensas; estanqueidade à água; verificação do comportamento do painel exposto à ação de calor e choque térmico; ensaios de delaminação. Ao final, em vista de inconformidades apontadas em alguns ensaios, constatou-se a necessidade de assegurar a qualidade no tratamento da matéria-prima e na colagem das lamelas, de modo a garantir a devida vida útil da edificação. Concluiu-se, também, que o CLT se apresenta, de fato, como uma alternativa extremamente promissora na construção civil. Contudo, seu emprego, deve ser planejado de maneira a se compreender e respeitar a intrínseca relação existente entre suas etapas construtivas e as soluções técnicas e arquitetônicas, para que se garanta adequado desempenho da edificação em uso. / Cross Laminated Timber (CLT) panels are a relatively new building component to the international construction sector. Their production in Brazil started around six years ago. Since its use is still scarce in the country, academic and technical references are still rare and there are uncertainties about the performance of the panels during the life of the building. In addition, CLT can be considered as an innovation, which is associated to pre-fabrication and digital technologies, being consequently different from usual building techniques. Therefore, the doubts concern not only the panels performance but also the appropriate design of the CLT building. In order to provide recommendations for architectural designs which will use Brazilian CLT panels, this research aims to extend the investigation of CLT in Brazil. The study focuses on structural performance and durability of CLT panels, according to the Brazilian regulation ABNT NBR 15575, and on the construction process of CLT buildings. The performance analysis is based on the following laboratory tests: retention and penetration of the wood preservatives used in the panels manufacture; soft body impact and hard body impact tests and suspended pieces loading tests; water tightness; heat and thermal shock test; delamination tests. Some of the tests results showed nonconformities. This indicates the importance of a quality control process of the wood preservation treatment and bonding of CLT layers, to ensure the proper performance of the building. In conclusion, CLT panels are indeed a promising alternative to the construction sector. However, its use must respect the intrinsic relation between construction steps, as well as technical and architectural solutions, in order to guarantee adequate performance of the CLT building.

This research study investigates the effect of micronized copper azole type C (MCA-C) preservative system on the rolling shear (RS) properties of CLT. In the first part of research, bonding performance of CLT panels treated at two retention levels, 0.96 kg/m3 and 2.5 kg/m3, were evaluated. Three structural adhesive systems, melamine formaldehyde (MF), resorcinol formaldehyde (RF) and one-component polyurethane (1C-PUR) were used to assemble visually graded No. 2 2×6 southern yellow pine (SYP) lumber while manufacturing CLT panels. For treated CLT panels, 1C-PUR provides better bonding performance test results. The RS properties of MCA-C treated CLT panels were studied in the second part of the research. The CLT panels were subjected to out-of-plane loading according to the EN 16351 standard. The mean values of RS strength and modulus of treated CLT were 1.89 MPa and 289.4 MPa respectively.

The use of timber in building structures is steadily increasing. cross laminated timber (CLT) is an engineered wood product made of an uneven number of layers of lamellas glued at an angle of 90 degrees to each other. This gives CLT high stiffness and strength to bending in all directions, and capability of taking load both in-plane and out-of-plane. Due to the large size of CLT elements, they allow for quick assembly of strong structures. Due to both economic and environmental reasons it is important for producers of CLT to optimize the use of the wood material by using the timber with higher stiffness and strength where it is most needed. This thesis is about evaluating the bending and shear stiffness of CLT elements, when used as plates, depending on the quality of wood used in the different layers. Four-point bending tests are carried out on elements of different compositions and a parametrized finite element model is created. Thus, the model is validated on the basis of experimental tests to evaluate the influence of different quality of different layers. The measured dynamic MoE proved to have good potential to be used as the longitudinal bending stiffness in an FE-model, with a deviation from the experimental tests of less than 1%. There is a strong correlation between the bending stiffness and bending strength of the plates. The effective rolling shear modulus in pine was calculated to be around 170 MPa for pine of dimension 40 x 195 mm2 . Grading the boards into two different classes used for different layers proved to increase the MoE of the plates by 11-17% for 3- and 5-layer CLT.

Cross-laminated timber (CLT) is an emerging sustainable engineered material with unique properties that in many ways make it superior to conventional construction material. CLT was invented in the 1990s and the volume produced have increased worldwide since then. It can be used in the load bearing structure for walls and floor slabs in the different typologies, e.g. residential and office buildings.The hygroscopic nature of wood allows it to exchange moisture with the surrounding environment. This may lead to an alteration of properties of wood-based materials such as CLT and can be accompanied by deformations and stresses. These effects influence the CLT’s structural stability, durability and safety.This study focuses on the consequences of moisture content variations in CLT structures, including mechanical properties like modulus of elasticity and bending stiffness (EI). Temperature and relative humidity were measured over three years in three positions along the thickness direction of a slab element on the first floor of House Charlie, a four-storey timber office building located in Växjö, Sweden.The investigation was carried out by mathematical modelling applying MATLAB® software aiming to find the moisture content as a function of time and thickness from the real-world data of House Charlie. The focus was on determining changes in modulus of elasticity and bending stiffness in response to moisture variation. The results showed that the moisture content within a slab of the building varied periodically following the seasonal variation throughout the years. The moisture content at the bottom of the slab was significantly lower compared to two other positions. According to the linear regression analysis, a linear relationship between the moisture content (MC) and positions across the CLT slab at each time step was defined. High R2 values, above 0.9, show the goodness of the fitted model. Applying the MC as a function of time and thickness into an available relationship of modulus of elasticity (E) could predict stiffness versus varied MC in the next step. The modulus of elasticity decreased with an increase in the moisture content over the studied period with a higher variation range at the bottom of the slab. In the final step, bending stiffness was assessed as a function of the changed moisture content. Bending stiffness increased periodically over time, attributed to overall more dry-out of the slab with time.The reported results of the present study give new insight into the behaviour of CLT structure over longer time periods. The recurring pattern in alterations stems from the reliance of bending stiffness on the modulus of elasticity function, which is in turn influenced by the linear relationship with moisture content exhibiting cyclic characteristics. The minimum and maximum values for EI were 3.5×1012 Nmm2 and 3.71×1012 Nmm2, respectively, a variation of approximately ±2.5% around the average. As the time steps increased, the bending stiffness also increased, given the progressive growth of the modulus of elasticity over time.

House construction today is largely project-based, where the buildings are tailored tounique conditions and locations that are rarely the same as another build on anotherbuilding site. In addition to the building itself and the building site, involved actorsusually also change from project to project. As a result of today's project-basedconstruction, there is a lack of a standardized and systematic work process forconstruction work. A systematic work process could contribute to all the players' pursuitof profit. To explore the possibilities of creating an improved work process, this study focusedon balconies of wooden houses. The purpose and objectives of the work were therefore designed to evaluate today'sconstruction work for the design of balconies in wooden houses, where possible areasof improvement were evaluated to create a systematic work process for constructorsin designing and dimensioning balconies in wooden houses.In order to achieve the purpose and objectives of the work, four questions have beendeveloped that focus on the production of systematic work processes, the current workprocess of the construction work, design methods and balconies in wooden houses.Existing research and published material were found through a literature and contextstudy to further develop the study’s work. Theory regarding systematisation and process development, balconies,dimensioning of supporting structures, etc. was the basis for how the work would becarried out. The systematized work process for balcony design was, however, createdusing information from the qualitative interview study with a total of eight (8)respondents in different roles I house building. The work process was then partiallytested in a quantitative verification. The work resulted in a systematic work process in the form of a checklist that includesgeneral tips as well as a chronological workflow that describes how, when, with whomand what should and can be done at the balcony design to get the best possible results.A description of the existing balcony types has also been developed to simplify workand to clarify important points and tasks in the design of a particular type of balcony. The workflow is divided into the activities of the design and dimensioning, such asstart-up, design and dimensioning of the balcony's main components, detail designand dimensioning of fastening components, drawing up drawings and assemblydescriptions, and follow-up and development of the work process. Based on the results of the study, the questions were answered with a description ofthe four (4) types of balcony, which were based on theory and were strengthened bymeans of empirical data from the respondents. Two (2) of the balcony types are viiiconsidered more common, balconies with pillars to land and rods above the balconyplate, where the latter is considered the most common in wooden houses at present.Today's construction work for designing and dimensioning balconies in woodenhouses is similar in large part, but due to the use of prefabrication and standardizationdegree the work differs from each other. The verification of a part of the work process resulted in a balcony solution with crosslaminated timber as a balcony slab and in a comparison between results from aproposed software and hand calculations. The comparison showed that the softwarecan be used for dimensioning balconies with cross laminated timber, with the exceptionthat the dimensioning for fire must be done by hand because of deficiencies in thesoftware's settings. The study has shown that systematisation is often based on LEAN Production, whichwas created by the Japanese automotive industry, which focuses on creating efficientwork processes by circularly examining, testing, evaluating and developing workprocesses. The conclusion of the work is that it is possible to systematise construction work, butunlike the manufacturing industry, the work process must have adjustment possibilitiesduring the work to meet the commonly occurring changes in house construction.However, in order for the systematisation work to be carried out, increasedunderstanding and involvement from and by other actors than constructors arerequired. A systematic work process together with type solutions and standardized calculationmethods can shorten the design time, improve and secure the solutions, and allowmore time for creative thinking to further improve the balcony solutions and the workprocess.

Previous studies have mainly focused on the behaviour of timber under uniformly distributed compression perpendicular to the grain (CPG) loads. However, there are many practical applications in which timber is loaded by non-uniformly distributed CPG loads. Different design and test codes like the Eurocode 5 (EC5), DIN 1052:2004, ASTM D143- 94 and EN-408:2010 only account for load configurations where timber is subjected to uniformly distributed loads. For specific uniformly distributed load (UDL) configurations the bearing capacity of timber (solid softwood timber or Glulam) in compression is adapted by using a load configuration factor (kc,90) according to EC5, the European code for design of timber structures. EC5 has no guidelines for cross-laminated timber (CLT) under UDL with the exception of the Austrian National Regulations for EC5. In this work, an experimental and numerical study on the bearing capacity and displacement behaviour of CLT subjected to non-uniformly distributed loading (NuDL) is conducted on eight different load configurations. A steel-CLT connection in which the CLT is partially loaded is used in this study. Finite element modelling, performed using the commercial software Abaqus CAE is used as the numerical simulation of the experimental study and is validated by experimental results. Load configuration factors (kc,90) from experimental results are compared with values from the Swedish CLT handbook (KL-Trähandbok). The outcome of the study shows that load configuration factor for NuDL cases is higher than for UDL cases. Hence, for same load configurations a lower CPG strength is required in NuDL than in UDL. Moreover, numerical results feature overall good congruence with the elastic phase of the experiments and have the potential to augment experiments in further understanding other complex steel-CLT connections

Cross-Laminated Timber (CLT) has recently become a popular construction material for building timber structures. One advantage of CLT is, that it can be used as floor, beam and wall element. As the arrangements of layers in CLT is in perpendicular direction to each other, it exhibits remarkable strength properties in both in-plane directions. However, the low stiffness and strength properties in compression perpendicular to the grain hinder application of CLT in high rising building, since forces are usually transferred from the wall elements through floor elements perpendicular to the grain. Thus, the aim of this thesis is to get a thorough understanding of the mechanical properties of such connections for different setups, including wood-wood connections, connections with acoustic layers and connections with screws. In addition, the wall was place at different positions on the CLT-floor element. Mechanical tests and numerical simulations, by means of finite element modelling (FEM) were carried out. CLT floor elements, consisting of 5-layers, were loaded by 3-layered CLT wall elements. Displacement and deformation were continuously measured by Potentiometers/LVDTs and an optical measurement system, respectively. Based on the experimental results compressive strength, slip curve and stiffness of the CLT connections were evaluated. Subsequently, results from FE-modelling were compared with experimental findings, which show a good agreement in elastic stiffness. Experimental results exhibited a pronounced influence of the wall position and connection setup on strength and stiffness. Central position of the wall showed higher mechanical properties than edge position. Highest strength and stiffness were found for screwed connections, where the wood-wood connections showed similar results. Connections with acoustic layers exhibited the lowest mechanical properties.

Knots are usually regarded as defects when grading lumber. In order to evaluate a member under out-of-plane loading, shear strength is one of the major mechanical properties, specifically, rolling shear (RS) strength is one of the critical mechanical properties of Cross-Laminated Timber (CLT), which determines the flexural strength of CLT under short-span bending loads. Lower grade lumber with a higher percentage of knots is recommended to be utilized for the cross-layer laminations which are mainly responsible for resisting shear stresses. Firstly, shear tests were performed in order to evaluate the effect of knots on longitudinal shear strength using shear blocks. After that, the effect of knots on the RS strength of 3-ply southern yellow pine CLT were investigated by experimental tests and an analytical model. Center-point bending tests with a span-to-depth ratio of 6 and two-plate shear tests with a loading angle of 14° were conducted on six CLT configurations composed of different types of cross layer laminations: clear flatsawn lumber with/without pith, lumber with sound knots with/without pith, and lumber with decayed knots with/without pith. The shear analogy method was implemented to evaluate the RS strength values from the bending test results, which were also compared against the results from the two-plate shear tests. It was found that: (1) The shear blocks containing sound knots had higher shear strength than matched clear shear blocks, the shear blocks containing unsound knots had lower shear strength than the matched clear shear blocks. (2) CLT specimens with cross-layer laminations with either sound knots or decayed knots had higher RS strength. (3) In general, the shear analogy method underestimated the RS strength of CLT specimens containing knots and pith.

Purpose: The purpose of this study was to investigate whether timber-concrete composite (TCC) floors made of a CLT-deck and casted concrete could be used as a method for increasing the use of wood as a building material. Method: The methods used in this degree project were a literature study, in which a number of laws of construction and different connector systems were studied, as well as an experiment consisting of bending tests on CLT-decks with casted concrete where SFS VB-screws were used as shear connectors. Results: The TCC-beams in the experiment behaved as expected and went to bending failure. The beams displayed an almost invisible slip between the materials despite the low composite action of 40,2 %. In addition, the beams had a higher bending stiffness on average than CLT-beams of the same height would have. Conclusions: Compared to floors made entirely of wood, TCC-floors with CLT add extra mass, stiffness, and better acoustic properties to the construction while maintaining a low floor height. The three main types of connectors used in TCC floors are mechanical, notched and glued-in connectors, where the latter two generates higher composite action and stiffness. Adhesive connection is another method with great potential, but there is still more research needed for this type of connection to be used.

Korrslimmat trä (KL-trä) är ett byggnadsmaterial som har ökat i popularitet och användning markant inom byggbranschen de senaste åren. Vid dimensionering av trähus är en av de mest komplicerade delarna att dimensionera förbanden. I stommen utgör förbanden en viktig del eftersom de håller ihop byggnaden. Därför är det viktigt att konstruktörer kan utföra säkra och ekonomiska dimensioneringar. Det saknas idag tydliga och pedagogiska guider med dimensioneringsexempel, vilka konstruktörer kan utgå från vid dimensionering av förband i KL-träkonstruktioner. Genom att granska de mest aktuella KL-trähandböckerna, jämföra dem med varandra och plocka ut de bästa delarna från varje handbok, har en sådan guide tagits fram i detta arbete med kompletterande dimensioneringsexempel. Guiden är tänkt att verka som stöd vid dimensionering av förband i KL-träkonstruktioner och förhoppningarna är att den i framtiden kan verka som underlag för framtagandet av en handbok med samlingar av stödjande beräkningsexempel. / Cross-laminated timber (CLT) is a rather new construction material that has increased its popularity and usage significantly within the building industry in the past years. In timber buildings, the connections are one of the most challenging parts to design. Thus, there are high demands put on structural engineers to make a safe and economic design. Today structural engineers have no specific and clear guideline that they can use as help for design of connections in CLT-buildings. By reviewing the most common CLT-handbooks, comparing them with each other, and picking out the best parts from each of the handbooks, a new guideline for design of connections in CLT-structures was developed in this thesis with complementary design examples. The guidelines main purpose is to act as help for the structural engineer when designing connections in CLT-structures. It is indented that the guideline acts as basis for the development of a future CLT-handbook with a collection of supporting calculation examples.