This work deals with the bearing capacity of wood based I-joists Finite element models were analyzed to determine the bearing capacity of I-joists, using the finite element software Abaqus CAE. The purpose of this study is to compare the results from the developed FE-models with experimental results, and with a previously proposed design formula. To perform the analyses finite element models were created. The model consists of three parts:, the web (made of shell element), the flanges and steel plates used at the supports and loading points (made of solid elements) To determine the bearing capacity of the I-joist two types of analyses were performed, a linear buckling analysis to check the risk of web buckling and a static (stress) analysis to check the risk of splitting of the flanges. This study shows that the steel plate length, in some cases, has little or no impact on primarily the splitting load. Furthermore, the buckling load decreases as the depth of the beam increases, the influence of the depth being proportional to 1/h2. The depth of the beam has no impact on the risk of splitting of the flange.

Engineered wood I-joists have grown in popularity as flooring and roofing structural systems in the past 30 years, replacing solid sawn lumber joists. Typical wood I-joists are manufactured with a very slender section, which is desirable to achieve higher flexural capacities and longer spans; however, this makes them susceptible to lateral torsional buckling failure. Continuous beam spans and uplift forces on roof uplift are potential scenarios where lateral instability can occur and reflects the need to investigate the lateral torsional buckling behavior of wood I-joists. Within this context, the present study conducts an experimental investigation on the material properties and the critical buckling load of 42 wood I-joist specimens. A 3D finite element model is built using the experimentally determined material parameters to effectively predict the observed buckling behavior of the specimens while also accounting for initial imperfections in the joists. The adequacy of other analytical models to predict the critical buckling load of wood I-joists are also investigated. It is demonstrated that the American design standard underestimates the critical buckling load of wood I-joists while the classical theory provides an adequate estimate of the buckling capacity. Furthermore, the effects of initial imperfections on the lateral torsional buckling behavior are discussed. The developed and verified FE model is used to reproduce the nonlinear buckling behavior of the wood I-joist and also to provide an accurate estimate of the lateral torsional buckling capacity using the linear buckling analysis.

Due to time, cost, and environmental challenges, wood has become a more common building material even for more complex buildings. Implementing the concept of Level of Development (LOD) on timber structures could provide a tool for BIM collaboration that may save cost and time, and in the early stages mediate wood as an available building material. Studies explain that LOD enables a high level of content and clarity as well as improved control of the design process. As the concept of LOD heavily focuses on general BIM visualisation, existing research at the time of the study lacks descriptions of how to implement LOD for specific projects. The study aims to develop a framework that could provide the industry with a possible implementation concept that could be further developed on other building systems. The goal of the study is to present a framework of a possible LOD implementation on a timber building system with a detailed description focusing on the structural engineer’s role during the design process. From that the questions of how to apply LOD on different project types as well as what data characteristics vary between these project types will be answered. Stated in previous studies, Integrated Project Delivery (IPD)A  is required for a successful design process is gained by utilising Integrated Project Delivery (IPD) and is especiallyalso essential when working with LOD. LOD is defined as five stages: starting with 100, then 200, 300, 350, 400, and finally 500. For each level of a building system, element, or assembly, the vagueness of information decreases and is therefore visualised differently in a BIM model. The study is based on a qualitative analysis of current data and related work about the design process, LOD, and timber buildings. The framework is mainly built upon five theories, the IPD process, the MacLeamy curve, BIM use purposes, data vagueness determination, and data requirement for timber projects. An interview study was conducted where projects using Masonite Beam’s standardised I-joist system were studied and implemented usingg the framework. The resulting framework presents the percentage information vagueness of how mature the information for a given objects is for different data properties and of each LOD level. The analysis leads to the conclusion that if fulfilling three criteria, 1: Following the IPD process, 2: An effort process similar to MacLeamy, and 3: Utilising BIM, the timber system can be implemented on the framework. However, the closer the project meets the criteria the closer the vagueness values will relate to the framework. The project that utilises a highly standardised building system with predefined data presents even lower vagueness values than the framework. Due to varying scales of project complexities, the data properties that showed the most diverse results between the projects were material information, geometric shape, and element dimensions. The findings from the study could be of further use in another research whose authors defined detailed graphical LOD visualisation in a BIM collaborative environment. The concept is strongly dependent on defined vagueness values that the authors of the research did not focus on how to define, which this framework does. Finding theories that support the assumptions made during the analysis development of the framework is continuing work that could strengthen the framework and its reliability. / Med tid -, kostnad- och klimatutmaningar har trä blivit ett mer vanligt byggnadsmaterial även för komplexa byggnader. Implementering av konceptet Level of Devlopment (LOD) på träkonstruktioner kan förse byggnadsindustrin med verktyg för BIM- kollaboration som kan spara på både kostnader och tid, och i tidigt skede framhäva trä som ett möjligt byggnadsmaterial. Studier förklarar att LOD kan bidraförse med en hög klarhetsgrad för olika innehåll, men även förbättra kontrollen under designprocessen. Då LOD-konceptet är starkt fokuserad på generell BIM-visualisering förklarar inte funna studier LOD- implementering för specifika projekt. Studien avser att utveckla ett framework (struktur) som kan förse byggnadsindustrin med ett möjligt implementeringskoncept som vidare kan anpassas till andra byggnadssystem. Målet är att presentera ett framework av en möjlig LOD implementering för ett träbyggandssystem med en detaljerad förklaring utifrån byggnadskonstruktörens roll i designprocess. Från detta kan frågor om hur man kan använda LOD för olika projekttyper samt vilka olika typer av information som varierar mellan dessa projekttyper besvaras. Tidigare studier visar En lyckad designprocess erhålls vi nyttjandet av att Intergrated Project Delivery (IPD) är nödvändigt för att uppnå en lyckad designprocess, särskiltvilket även är essentiellt när man arbetar meddet kommer till LOD. LOD definieras av fem stadier som går: från 100, 200, 300, 350, 400 ochtill 500. För varje nivå minskas osäkerhetsvärdet för en viss information tillhörande ett byggnadssystem, element eller assmembly, och är därmed olika grafiskt visualiserad i en BIM- modell. Studien baseras på en kvalitativ analys av befintliga data and och relaterade studier inom designprocessen, LOD och träbyggnader. Frameworket är huvudsakligen uppbyggt på fem teorier: IPD- processen, MacLeamy- kurvan, användningssyften av BIM, informationsosäkerhetsbestämmelse samt data som behövs för träbyggnadsprojekt. En intervjustudie är utförd där projekt utförda med Masonite Beams standardiserade trä I-balkar av trä studerades och implementerades på frameworket. Det resulterande frameworket presenterar procentuella osäkerhetsvärden som beskriver i vilken grad informationen tillhörande ett objekt går att lita på för olika informationskategorier och för varje LOD- nivå. Analys leder till slutsatsen att om följande tre kriterium uppfylls; 1. Följer IPD- processen, 2. Liknande arbetskurva som MacLeamy, 3. Använder BIM, kan ett träsystem implementeras på frameworket användas för ett träsystem. Det visar sig att desto närmare ett projekt uppfyller kriterierna desto närmare visar sig osäkerhetsvärdena stämma överens med de värden som presenteras för enbart frameworket. Projektet med hög användning av standardiserat byggnadssystem och förbestämdt data påvisar till och med lägre osäkerhetsvärden än vad frameworket gör. På grund av varierade grad av projektkomplexitet visar datakategorierna; materialinformation, geometrisk form och elementdimensioner störst olikheter mellan projekten i resultatet. Resultatet skulle vidare kunna användas till en annan forskningsstudie vars författare definierat detaljerade grafiska LOD visualiseringar i en BIM-kollaborationsmiljö. Konceptet är starkt beroende av givna osäkerhetsvärden som författarna och studien inte fokuserade på att definiera, vilket detta framework gör. Vidare arbete som kan stärka frameworket är att hitta teorier som stödjer de antaganden som gjorts under frameworkets analytiska utvecklande.

The research summarized the experimental analysis and finite element modeling of the lateral and rotational response of unbraced wood composite I-joists to worker loads. All experimentation and modeling was conducted on simply supported I-joists varying from 11-7/8 inches to 14 inches in depth and 20 feet to 24 feet in length. I-joists were subjected to static and dynamic loads. The deflections of the top and bottom flanges, as well as the rotation, were measured or calculated at both one-half and one-quarter the span length. The overall goal of this project is to accurately model the lateral and rotational displacements caused by human load effects. I-joists were first tested statically by subjecting each joist to a three point bending test, free from all lateral restraints. This test was necessary to prove that the performance of the joists was repeatable. Lateral and rotational stiffness of the joist were calculated at one-half and one-quarter of the span length. The static experimental tests results were statistically analyzed using an analysis of variance (ANOVA) test. The results from this analysis indicated no difference between repetitions of the same joist; however, the test did indicate that there was a significant difference between joists of the same manufacture and size. Dynamic testing was then conducted. Dynamic loads were induced by having test subjects traverse each I-joist. The resulting loads induced at the top and bottom flanges were recorded for use in the finite element model. The lateral deflections and induced loads were compared to the static weight of the test subject and analyzed with an ANOVA test. The results indicated an increase in both the induced load and resulting deflection with an increase in weight. The analysis also indicated an increase in load and deflection with a decrease in lateral and rotational joist stiffness. The recorded load values from the dynamic test were used as inputs into a finite element model. The resulting lateral deflections of the midpoint and quarter point were generated. The rotation of the beam was calculated from the difference between the top and bottom flange. Experimental results and finite element model results were compared by calculating a running average of the error between the acquired data and the finite element model. The model was said to be valid until the average model error reached 10 percent of the maximum acquired test value. All six deflection readings were analyzed in this manner. The percent of beam at which the model no long represented the test data was determined for each data set. This point was averaged across all deflection readings of similar joists and across all data sets of the same joist type. The model predicted the 20 foot long 11-7/8 and 14 inch deep joists until 54.5 percent and 51.2 percent, respectively, of the beam completed by the test subject. However, the 24 foot long 11-7/8 inch deep joist was only accurate to 31.2 percent of the beam completed by the test subject. Differences in peak values, and the time at which the peak values occurred were also analyzed using an ANOVA test. There was a significant difference between the peak values of the acquired test data and the deflections generated with the finite element model. However, there was no significance within the time that the peak values occurred between the model and experimental results. A simplified pseudo dynamic analysis was conducted using a constant percentage of the test subject's static weight applied to the top and bottom flange. This approximation proved adequate for the lateral displacement and rotation of the 11-7/8 inch and 14 inch deep and 20 foot long I-joists. However, the model became un-conservative for the 11-7/8 inch deep and 24 foot I-joists. / Master of Science

The research summarized in this thesis is comprised of an experimental analysis of the mechanical behavior of a wood composite I-joist with different bracing configurations exposed dynamic walking loads. Three 16 in. deep GPI® 65 I-joists were simply supported and laid parallel to each other, while the bracing was attached to the top flange. Five different brace stiffnesses were used: zero stiffness (control), 1.2 lb/in., 8.5 lb/in., 14.0 lb/in. and infinitely stiff. Two different brace configurations were used: one-quarter of the span length (60 in.) and one third the span length (80 in.). The dynamic walking loads consisted of human test subjects attached to a safety platform walking across the I-joist at a designated pace. Experimental results for this research consisted of the I-joist's lateral accelerations, lateral displacements and twist. An Analysis of Covariance (ANCOVA) was used for the statistical analysis of the results and was performed for each measurement. The statistical analysis determined the effects of different bracing configurations, stiffnesses, measurement locations as well as test subjects' weight and occupation. Test results and observed trends are provided for all test configurations. Lateral displacement and twist experienced the same trend throughout the experiment: as brace stiffness increased, lateral displacement and twist decreased. This correlated with basic beam theory and bracing fundamentals. It should be noted that as the stiffness increased, the effect on lateral displacement and twist response decreased. However, the trend for lateral displacement and twist was not observed for the lateral accelerations. The 1.2 lb/in. brace stiffness had much larger lateral accelerations for the 60 in. brace configuration throughout the span and were also larger at the bracing point for the 80 in. brace configuration. This could have been due to the energy applied from the springs or a natural frequency of the I-joist system could have been reached during testing. However, the other four brace stiffnesses followed the same trend as the lateral displacements and twist. In addition, this research demonstrates a method for the measurement of lateral buckling due to worker loads. The mitigation of lateral buckling can use appropriate bracing systems. The measurements of the change in lateral buckling behavior can be used to develop safety devices and ultimately ensure the protection of construction workers. / Master of Science

Recent research has shown that a significant number of the falls from elevation occur when laborers are working on unfinished structures. Workers walking on wood I-joists on roofs and floors are prone to fall hazards. Wood I-joists have been replacing dimension lumber for many floor systems and a substantial number of roof systems in light-frame construction. Wood I-joists are designed to resist axial stresses on the flanges and shear stresses on the web while minimizing material used. However, wood I-joists have poor resistance to applied lateral and torsional loads and are susceptible to lateral-torsional buckling instability. Workers walking on unbraced or partially braced wood I-joists can induce axial and lateral forces as well as twist. Experimental testing demonstrated that workers cause lateral-torsional buckling instability in wood I-joists. However, no research was found related to the lateral-torsional buckling instability induced by individuals walking on the wood I-joists. Furthermore, no research was found considering the effects of the supported end conditions and partial bracing in the lateral-torsional buckling instability of wood I-joists. The goal of this research was to derive mathematical models to predict the dynamic lateral-torsional buckling instability of wood composite I-joists loaded by individuals walking considering different supported end conditions and bracing system configurations. The dynamic lateral-torsional buckling instability was analyzed by linearly combining the static lateral-torsional buckling instability with the lateral bending motion of the wood I-joists. Mathematical models were derived to calculate the static critical loads for the simply supported end condition and four wood I-joist hanger supported end conditions. Additionally, mathematical models were derived to calculate the dynamic maximum lateral displacements and positions of the individual walking on the wood I-joists for the same five different supported end conditions. Three different lean-on bracing systems were investigated, non-bracing, one-bracing, and two-bracing systems. Mathematical models were derived to calculate the amount of constraint due to the lean-on bracing system. The derived mathematical models were validated by comparison to data from testing for all supported end conditions and bracing systems The predicted critical loads using the static buckling theoretical models for the non-bracing system and the static buckling theoretical models combined with the bracing theoretical models for the simply and hanger supported end conditions agreed well with the critical loads obtained from testing for the two wood I-joist sizes investigated. The predicted maximum lateral displacements and individual positions using the bending motion theoretical models for the simply and hanger supported end conditions agreed well with the corresponding maximum lateral displacements and individual positions obtained from testing for both wood I-joist sizes. Results showed that; a) the supported end condition influenced the critical loads, maximum lateral displacements and individual positions, b) the bracing system increased the critical loads and reduced the maximum lateral displacements, c) the critical load increased as the load position displaced away from the wood I-joist mid-span, d) the critical load reduced as the initial lateral displacement of the wood I-joist increased and e) the wood I-joist mid-span was the critical point in the dynamic lateral-torsional buckling instability. / Ph. D.

Devido à importância da madeira na construção civil e a preocupação com o impacto ambiental, a engenharia passou a se preocupar com a racionalização de seu uso por meio da apresentação de produtos engenheirados, buscando melhorar as propriedades técnicas das construções em madeira. Novos modos de manufatura foram introduzidos, principalmente no campo da engenharia estrutural, fazendo com que se desenvolvessem elementos comprovadamente superiores em suas propriedades físico-químicas e econômicas a outros normalmente usados. Neste trabalho foram avaliadas as propriedades de resistência e elasticidade de vigas de madeira de seção transversal \"I\", utilizadas na sustentação de painéis de fôrmas para concreto armado e em obras civis estruturais, incluindo as emendas de mesas e alma-mesa utilizadas em sua fabricação, por meio de ensaios de flexão e cisalhamento na linha de cola. Essas vigas são comercialmente chamadas de H2O devido a sua altura de 20 centímetros, sendo compostas de mesa em madeira serrada, almas em compensado sarrafeado, compensado laminado ou madeira serrada, e dois tipos de adesivos o de poliuretano e o de resorcinol-formol. As análises visaram comprovar a eficiência e viabilidade técnica da fabricação e utilização destes materiais nestas vigas. A configuração de viga H2O que apresentou os melhores resultados comparativamente com o mínimo exigido nos ensaios especificados pela norma européia EN 13377:2002 foi a composta por alma de compensado, emenda dentada e colada com o adesivo de Resorcinol-Formol. / Due to the importance of wood in construction and the concern about the environmental impact, engineers have worried about the rationalization of its use through the development of engineered products, seeking the improvement of the technical properties. In this study, the I-beams built with reforestation wood were used for concrete formwork purpose. Their mechanical properties and the connections between flanges and web used in its manufacture were evaluated by means of bending tests and shear in the glue line. These beams are commercially called H2O. The flanges were made from Pinus Oocarpa, the webs were made from laminated plywood, block plywood, and Pinus Oocarpa, and two types of adhesives were used: polyurethane and resorcinol-formaldehyde. The H2O beam configuration showed the best results compared to the minimum required by European standard EN 13377:2002 was with the flange made from lumber, glued with resorcinol-formaldehyde and the web of laminated plywood.

Devido à importância da madeira na construção civil e a preocupação com o impacto ambiental, a engenharia passou a se preocupar com a racionalização de seu uso por meio da apresentação de produtos engenheirados, buscando melhorar as propriedades técnicas das construções em madeira. Novos modos de manufatura foram introduzidos, principalmente no campo da engenharia estrutural, fazendo com que se desenvolvessem elementos comprovadamente superiores em suas propriedades físico-químicas e econômicas a outros normalmente usados. Neste trabalho foram avaliadas as propriedades de resistência e elasticidade de vigas de madeira de seção transversal \"I\", utilizadas na sustentação de painéis de fôrmas para concreto armado e em obras civis estruturais, incluindo as emendas de mesas e alma-mesa utilizadas em sua fabricação, por meio de ensaios de flexão e cisalhamento na linha de cola. Essas vigas são comercialmente chamadas de H2O devido a sua altura de 20 centímetros, sendo compostas de mesa em madeira serrada, almas em compensado sarrafeado, compensado laminado ou madeira serrada, e dois tipos de adesivos o de poliuretano e o de resorcinol-formol. As análises visaram comprovar a eficiência e viabilidade técnica da fabricação e utilização destes materiais nestas vigas. A configuração de viga H2O que apresentou os melhores resultados comparativamente com o mínimo exigido nos ensaios especificados pela norma européia EN 13377:2002 foi a composta por alma de compensado, emenda dentada e colada com o adesivo de Resorcinol-Formol. / Due to the importance of wood in construction and the concern about the environmental impact, engineers have worried about the rationalization of its use through the development of engineered products, seeking the improvement of the technical properties. In this study, the I-beams built with reforestation wood were used for concrete formwork purpose. Their mechanical properties and the connections between flanges and web used in its manufacture were evaluated by means of bending tests and shear in the glue line. These beams are commercially called H2O. The flanges were made from Pinus Oocarpa, the webs were made from laminated plywood, block plywood, and Pinus Oocarpa, and two types of adhesives were used: polyurethane and resorcinol-formaldehyde. The H2O beam configuration showed the best results compared to the minimum required by European standard EN 13377:2002 was with the flange made from lumber, glued with resorcinol-formaldehyde and the web of laminated plywood.

In this thesis an alternative exterior wall construction for a specific building isinvestigated. The focus has been on investigating the material straw as a possiblecomponent in the future project Kulturborgen in Skåne, Sweden.Straw is a bio-based building material which, with a consideration to the climate crisis,has become a viable alternative intended to minimize carbon dioxide emissions from thebuilding sector. Through a compilation of the latest research on the material, theproperties of straw are presented in the theory chapter. Previous studies have shown thepotential of straw to be used as a load-bearing frame in house construction. However, dueto an adaptation to existing blueprints, the focus in this project has been on using straw asonly an insulating material together with load bearing I-joists. By modeling in AutodeskRevit and making calculations on the structure's load bearing capacity and thermalinsulation, a solution on an outer wall has been presented. The work culminates in aproposal for detailed drafts for a specific building that can become the basis for a possiblefurther development. / Halm är en restprodukt från odling av säd och andra grödor och räknas ur miljösynpunkttill ett mer hållbart alternativ än de konventionella byggnadsmaterial som producerasidag. Växtbaserade byggnadsmaterial som halm kan utgöra kolsänkor tack vare sinförmåga att fånga upp koldioxid från atmosfären och med tanke på en störreklimatmedvetenhet har biobaserade material blivit ett aktuellt alternativ ämnat attminimera koldioxidutsläppet från byggbranschen. Tidigare studier visar att halm har godaförutsättningar att användas som ett isolerande material tack vare sin lågavärmekonduktivitet. Halm kan även användas som en självbärande stomme eftersom denhar en hög lastöverföringsgrad. I kombination med en regelkonstruktion av annat materialkan halmen användas enbart som ett isolerande skikt mellan reglarna.Kulturborgen är ett storskaligt byggnadskomplex projekterat som en ringborg med ettöppet torg i mitten. Den byggnad som har studerats i detta examensarbete är enbart en deli komplexet, nämligen ett vandrarhem i två plan. I arbetet undersöks de möjligheter somfinns när en betongväggkonstruktion ersätts med ett biobaserat alternativ samt vilkakonsekvenser det kan få för projekteringen.I detta examensarbete undersöks en alternativ ytterväggskonstruktion för Kulturborgen.Fokus har varit att undersöka materialet halm som en möjlig beståndsdel i det framtidaprojektet Kulturborgen i Skåne, där den ursprungliga planen var att uppföra byggnadenmed prefabricerade betongelement.I en sammanställning av den senaste forskningen om materialet har halmens egenskaperoch tillämpning inom byggbranschen redovisats i ett teorikapitel. Olika metoder för attanvända halm som ett byggnadsmaterial har också tagits upp med avsikt att undersökavilken byggnadsmetod som passar bäst för Kulturborgen.På grund av anpassning till befintliga ritningar på Kulturborgen har användningen avhalm i detta projekt behandlats som enbart ett isoleringsmaterial där halmen är ett 400mm isolerande skikt i kombination med lättreglar med en bärande funktion. Lättreglarvaldes därför att de tack vare sitt I-tvärsnitt har en lägre andel trä än en regel med ettrektangulärt tvärsnitt. Detta gör att lättreglar är materialbesparande och ett lägre U-värdekan erhållas.En modell har tagits fram genom användning av programmet Autodesk Revit.Beräkningar på lättreglar har gjorts för att säkerställa att byggnaden klarar av alla lasterden utsätts för. U-värdesberäkningar utfördes för att kontrollera att vägguppbyggnadensom valdes fick ett U-värde som låg under 0,15 W/m2K, vilket hamnar inom en rimliggräns för en yttervägg. Slutligen har en lösning på en ytterväggskonstruktion presenterats.Arbetet mynnar ut i ett förslag på detaljlösningar för Kulturborgens vandrarhem ochdessa kan ligga till grund för en eventuell vidareutveckling.