Current research at the University of Canterbury is investigating the performance of a new type of timber floor system made of a timber-concrete composite. This newly proposed timber floor system uses double LVL members connected together with screwed connections to form one larger LVL member. Recent large scale fire tests showed that the joint between these two screwed LVL members opened up during fire exposure. This opening phenomenon causes concerns as the overall charring rate of the joint LVL members is subsequently increased. The main focus of this research, therefore, was to examine the charring rate for different cross sections of single and double LVL members, with different connection types for the double members. The single LVL member examined was 63mm width whereas the double LVL members examined were 90mm and 126mm width. Three connection types were investigated which were nails, screws and glue. Their corresponding charring rates and burning characteristics were examined both in the small furnace provided by the University of Canterbury and in the pilot furnace at the Building Research Association of New Zealand (BRANZ) in Wellington. The overall finding from the small furnace testing shows that the overall average side charring rate for a 30 minute fire exposure was 0.76mm/min; whereas the overall average side charring rate for a 60 minute fire exposure was 0.66mm/min. Moreover for a 30 minute fire exposure, the average bottom charring rates for nail, screw and glue connected double LVL members were 1.00mm/min, 0.83mm/min and 0.83mm/min, respectively. For a 60 minute fire exposure, the average bottom charring rates for screw and glue connected double LVL members were 0.97mm/min and 0.57mm/min, respectively. The nail connected double LVL members experienced the highest bottom charring rate as it suffered the largest bottom separation which allowed the heat to travel into the mid-span resulting in a higher bottom charring rate. Out of these three connection types, the glued connection was the best connection type. Experimental findings were compared with the simulated results generated by the SAFIR finite element program. Experimental findings were also used to modify the spreadsheet design tool which predicts the fire resistance rating of a timber-concrete composite floor under user defined load conditions and floor geometries.

The fire resistance of timber connections is relatively unknown in the construction and design industries even though they are widely used. This research focuses on the fire resistance of nailed, screwed, bolted and self-drilling doweled connections in laminated veneer lumber (LVL) timber. These connections have been found to have high strength under cold or normal temperature but hardly achieved 30 minutes fire rating in the furnace tests. To establish the performance of connections, an investigation was carried out on the compressive strength of connections by having compressive tests using an Instron Testing Machine. Similar connections were tested at simulated fire conditions under constant load in a custom-built furnace. The different fasteners used and the arrangement of the connections gave different connection strengths at ambient and elevated temperature.

Timber has experienced new interest as a building material in recent times. Although traditionally in New Zealand it has been the main choice for residential construction, with recently introduced engineered wood products like Laminated Veneer Lumber (LVL), the use of timber has developed to other sectors like commercial, industrial, and multi-story buildings. The application of timber in office and commercial buildings poses some challenges with requirements for long span timber beams yet with holes to pass services. The current construction practice with timber is not properly suited for the aforementioned types of structures. There has been significant progress in designing timber structures since the introduction of timber codes like NZ3603-Timber Structures Standard; however, there are still a number of problems such as holes in beams not being addressed in the code. Experimental and numerical investigation is required to address the problem properly. In Europe, there have been a few attempts to address the problem of cutting holes and strength reduction because of holes/penetrations in glulam beams. However, LVL has not received much attention due to smaller production and use. While other researchers are focusing on glulam beams with holes, this research is targeting LVL beams with holes. This thesis extends existing knowledge on LVL beams with holes and reinforcement around the holes through experimental tests and numerical analysis. An experimental program on LVL specimens has been performed to indicate the material properties of interest that will be used in the analysis and design chapters through whole of the thesis. A wide-ranging experimental program was also performed on beams with holes, and beams with reinforcement around the holes. The experimental program pushes forward existing methods of testing by measuring the load in the reinforcement

An extensive research program is on-going at the University of Canterbury, New Zealand to develop new technologies to permit the construction of multi-storey timber buildings in earthquake prone areas. The system combines engineered timber beams, columns and walls with ductile moment resisting connections using post-tensioned tendons and eventually energy dissipaters. The extensive experimental testing on post-tensioned timber building systems has proved a remarkable lateral response of the proposed solutions. A wide number of post-tensioned timber subassemblies, including beam-column connections, single or coupled walls and column-foundation connections, have been analysed in static or quasi-static tests. This contribution presents the results of the first dynamic tests carried out with a shake-table. Model frame buildings (3-storey and 5-storey) on one-quarter scale were tested on the shake-table to quantify the response of post-tensioned timber frames during real-time earthquake loading. Equivalent viscous damping values were computed for post-tensioned timber frames in order to properly predict their response using numerical models. The dynamic tests were then complemented with quasi-static push and pull tests performed to a 3-storey post-tensioned timber frame. Numerical models were included to compare empirical estimations versus dynamic and quasi-static experimental results. Different techniques to model the dynamic behaviour of post-tensioned timber frames were explored. A sensitivity analysis of alternative damping models and an examination of the influence of designer choices for the post-tensioning force and utilization of column armouring were made. The design procedure for post-tensioned timber frames was summarized and it was applied to two examples. Inter-storey drift, base shear and overturning moments were compared between numerical modelling and predicted/targeted design values.

A new structural system for multi-storey timber buildings has been developed over the last seven years at the University of Canterbury. The system incorporates large timber structural frames, whereby semi-rigid beam-column connections are created using post-tensioning steel tendons. This system can create large open floor plans required for office and commercial buildings. Several material properties of the engineered timber used were determined based on small-scale experimental testing. Full-scale testing of beams, connections and frames resulted in a more comprehensive understanding of the behaviour of such systems. Numerical, analytical and framework models also led to the development of design equations and procedures which were validated with the acquired experimental data.

Med teknikens framfart finns ett ökat behov av numeriska simuleringar avträförband. För att erhålla ett mer tillförlitligt resultat finns ett behov av noggrannarefriktionskoefficienter vid olika förhållanden som påverkar lastöverföring.I den här studien undersöks friktionen mellan materialen LVL (laminated veneerlumber; fanerträ) och stål. Målet är att studien ska resultera i friktionskoefficienterför olika varierande förhållanden som sedan kan användas vid t.ex. olika numeriskasimuleringar.Friktionstesterna utfördes genom att succesivt öka vinkeln på glidytan i form av enstålplatta där en provkropp var placerad. Vinkeln ökades tills det att provkroppenhamnade i rörelse, den uppnådda vinkeln registrerades och räknades sedan om till enfriktionskoefficient.Totalt utfördes 1 800 friktionstester för att ge god statistisk grund åt de slutgiltigamedelvärdena för friktionskoefficienterna. Undersökningen resulterade i enfriktionskoefficient i form av ett medelvärde för respektive varierande förhållande.

Forskning inom friktion idag är mest inriktad på friktion mellan metaller samt friktion mellan metaller och andra material. Friktion mellan träytor förekommer i en begränsad omfattning och tas sällan upp. I byggsammanhang och på många andra områden behöver kunskapen om friktion ökas och tillförlitligheten hos antagna friktionskoefficienter behöver förbättras. En bestämning av statiska friktionskoefficienter mellan träytor parallellt fiberriktningen har gjorts för LVL av barrträ, respektive LVL av bok. Bestämningen av friktionskoefficienter gjordes genom experimenten med hjälp av ett lutande plan. En jämförelse av de statiska friktionskoefficienterna visar att en råare yta och en lägre densitet ger en högre friktionskoefficient.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The aim of the present research was to evaluate the physical and mechanical properties of LVL reinforced with fiberglass with two types of resins. Pinus elliottii veneers with 1,5 mm thickness were used to manufacture of the LVL panels. The panels were manufactured in two steps. The first one was the assembling of the LVL panels with nine layers of wood veneer glued with phenol-formaldehyde resin. The second step consisted into reinforcing the LVL with fiberglass impregnated with epoxy resin (E) or isophthalic resin (I). The treatments were: panels without reinforcement (T), panels reinforced with one fiberglass layer (E T1 e I T1), panels reinforced with two fiberglass layers (E T2 e I T2) and panels reinforced with four fiberglass layers (E T3 e I T3). The size of panel was 45 cm x 34 cm x 1,08 cm. The physical properties tested were density and moisture content. The mechanical properties tested were: static bending in flatwise and edgewise position, modulus of elasticity (MOE) and modulus of rupture (MOR); glueline shear strength by compression loading; hardness test; and non-destructive test by ultrasound method. The epoxy and the isophthalic resin showed similar mechanical performance among the different treatments.The resistence and stiffness of the panels were influenced by the reinforcement. The MOE in flatwise position was influenced by one reinforcement layer and the MOR was influenced by two reinforcement layers. In the edgewise position the MOE and the MOR values remained constant among the treatments with two fiberglass reinforcement layers. The MOE in nondestructive test had higher values when compared with the destructive method, however these values remained stable with two layers of reinforcement. Two layers of reinforcement on the tensile and compression side had higher values in hardness test. The epoxy resin presented higher glueline resistence and higher percentage of wood failure. Isophthalic and phenolic resin presented similar values of glueline strenght, however the isophthalic resin had lower percentage of wood failure. Thus, the reinforcement with one layer of fiberglass imprenated with epoxy resin on the tensile side would be enough to promote the mechanical qualities of LVL. / O objetivo desta pesquisa foi avaliar as propriedades físico-mecânicas de painéis de lâminas paralelas (LVL) reforçadas com camadas de fibra de vidro inpregnadas com dois tipos de matrizes. Lâminas de madeira de Pinus ellliottii com espessura de 1,5 mm foram utilizadas na fabricação dos painéis. A montagem dos painéis foi realizada em duas etapas. A primeira consistiu na fabricação dos painéis LVL com nove camadas de lâminas de madeira unidas com resina à base de fenol-formaldeído na gramatura de 190 g/m2 em linha simples. E a segunda etapa consistiu na aplicação do reforço de fibra de vidro impregnado com resinas epóxi (E) ou poliéster isoftálica com NPG (I). Os tratamentos utilizados foram: painéis sem reforços (T), painéis com uma camada de fibra de vidro (E T1 e I T1), painéis com duas camadas de fibra de vidro, sendo uma camada no lado de compressão e uma camada no lado de tração (E T2 e I T2) e painéis com quatro camadas de fibra de vidro, duas camadas do lado de compressão e duas camadas no lado de tração separados por uma lâmina de madeira (E T3 e I T3). Foram realizadas três repetições por tratamento, totalizando 21 painéis. As dimensões finais dos painéis foram 45 cm x 34 cm x 1,08 cm. Para determinar a qualidade dos painéis LVL foram avaliadas as propriedades físicas (massa específica e teor de umidade) e a resistência mecânica (flexão estática na posição flatwise e egdewise, resistência ao cisalhamento, dureza Janka e teste não destrutivo utilizando ultrassom). A resina epóxi e a resina isoftálica apresentaram as mesmas qualidades mecânicas nos diferentes tratamentos. A aplicação do reforço influenciou na resistência e na rigidez do painel. Na flexão estática na posição flatwise o módulo de elasticidade (MOE) foi influenciado por uma camada de reforço e o módulo de ruptura (MOR) por duas camadas de reforço. Na posição edgewise os valores de MOE e do MOR se mantiveram estáveis com a aplicação de duas camadas de reforços de fibra de vidro. O MOE pelo método ultrassônico apresentou valores maiores quando comparado com o método estático; em ambos os métodos os valores mantiveram-se estáveis com a aplicação de duas camadas de reforço. A dureza Janka foi maior para as painéis com mais camadas de fibra de vidro na posição de tração e compressão. A resina epóxi apresentou maior resistência ao cisalhamento e maior percentual de falhas na madeira, enquanto que a resina isoftálica, apesar de apresentar valores de resistência similares à fenólica, não apresentou boa adesão à madeira, representada pelo baixo percentual de falhas na madeira. A aplicação de uma camada de reforço de fibra de vidro com resina epóxi na posição de tração seria o suficiente para melhorar as qualidades mecânicas dos painéis LVL fabricados com lâminas de madeira de pinus unidas com fenol-formaldeído.

Moderna Trähus vill undersöka möjligheten till att byta ut LVL-balk mot lättbalk men ändå bevara samma byggmetod. Metoden innebär att balkarna i mellanbjälklaget sänks med 30 mm under badrum. Rapporten presenterar LVL- och lättbalks egenskaper. Olika resultat från kostnadsberäkningar, hållfasthetsberäkningar och laborationstest baserat på standard EOTA TR002 presenteras i rapporten. / Moderna Trähus will investigate the possibility of replacing the LVL-beams with light composite wood-based beams, yet preserving the same construction method. The method means that the beams in the intermediate floor will be taking down 30 mm under the bathroom. This report presents the characteristics of both LVL-and light composite wood-based beams. The report also present different results from cost calculations, strength calculations and laboratory test based on the standard EOTA TR002.

Afin de valoriser au mieux le bois de feuillu de qualité secondaire, il est important de comprendre ses propriétés et d'optimiser ses propriétés mécaniques. La variabilité de certaines propriétés structurelles, physiques et mécaniques du bois de hêtres et de chênes issus d’éclaircis a été étudiée. Des billons tirés de ces arbres ont été déroulés en trois épaisseurs (2.1, 3, and 4.2 mm). La qualité du placage a été évaluée en mesurant la proportion du nœud et les fissurations. Les propriétés mécaniques du LVL (lamibois) réalisé à partir de ces placages ont été mesurées par méthode destructive et non destructive. Chez les deux espèces, le bois juvénile est concentré dans une petite zone près de la moelle, de sorte qu'il y aura peu ou pas de bois juvénile déroulé. Les propriétés mécaniques et physiques du bois des deux espèces sont fortement influencées par sa densité. Le placage de 3 mm d'épaisseur a fourni les propriétés mécaniques optimales pour le LVL pour les deux espèces. Ces propriétés mécaniques sont comparables à celles de LVL réalisés à partir d'autres essences de feuillus. Le placage interne a fourni du LVL avec une densité plus élevée, mais des propriétés mécaniques plus faibles en raison de sa proportion de nœuds plus élevée. / To improve the value of secondary quality hardwood, it is important to understand its wood properties and optimize its mechanical properties. The variability of some structural, physical and mechanical properties of wood from beech and oak trees issued from thinning was studied. Logs from these trees were rotary peeled in three different veneer thicknesses (2.1, 3, and 4.2 mm). Veneer quality was assessed by measuring the veneer knot proportion and checking properties. The mechanical properties of LVL (laminated veneer lumber) made from these veneers were measured using the static and dynamic method. Juvenile wood in both species is concentrated in a very small area near the pith thus there will be no or low part juvenile wood peeled. The wood mechanical and physical properties of both species were strongly influenced by the wood density. The 3 mm thick veneer provided the optimal mechanical properties for LVL for both species. Such mechanical properties are comparable to LVL made with other hardwood species. The internal veneer provided LVL with higher density, but lower mechanical properties as a result of its higher proportion of knots.