Two computer simulation models were developed to address harvest system - stand assignment and wood flow variability problems in the southeast United States. The Harvest System Assignment (HSA) model is used to evaluate the impact of a particular stand assignment on harvest system effectiveness and is designed to assist with harvest system assignment decisions. Four general harvesting systems: manual, mechanized, shovel and cut-to-length can be modeled to harvest timber, from standing trees to processed logs loaded on to trucks. Model testing showed that as terrain, tract and system characteristics changed, the effectiveness of each of the four systems varied. The most effective system can be determined for any combination of terrain, tract and system characteristics. The model output shows production potential as well as cost per unit, and identifies the causes and magnitude of inefficiency. The Machine Allocation (MA) model is used to evaluate the potential of a given machine combination and is designed as a research tool to investigate the cause and impact of machine interactions. This model has a defined system structure and can incorporate up to five machines for each of three phases in the harvesting operation: felling, skidding and processing. Particular system configurations can be evaluated and possible improvements to machine combination determined. The HSA model is a widely applicable tool that will be available for industry in the southeastern United States. It has utility for training of personnel and for operational use. The MA model is a detailed tool that will be used in a research capacity to advance harvesting system management. / Master of Science

Hardwood management has been discouraged because of long rotations, low stumpage values, expensive treatments, and an undependable market (Bechtold and Phillips 1983). Knowledge gaps on how various biological factors affect hardwood growth also exist. Stand improvement methods attempt to shift growth to desirable stems. Three different hardwood stand improvement treatments were evaluated. A pre-commercial chemical thin occurred in a twelve year old stand in 1990. In 1995, two of the treatments showed a significant increase in dbh over the control. However, the 2004 measurements of the stand did not find any significant differences between treatments. A case study examined paired plots throughout the state of Virginia where the crown touching crop tree release method was applied. In both the Piedmont and Ridge and Valley regions of the state an increase in dbh was observed. Finally, a timber stand improvement study examined different treatments in a 60-80 year old stand, but did not result in any significant increases in volume after three years. When oaks are harvested or a major disturbance occurs, the number of oaks that regenerates is less than there were previously (Smith 1992). Therefore, oak regeneration is a problem and methods are needed to facilitate oak regeneration (Smith 1992). One method of oak regeneration was examined. Burning five years after a deferment cut did not result in significantly more stems of oak regeneration. Various reductions in basal area also did not result in an increase in oak regeneration under our 60-80 year old timber stand improvement study. These studies attempt to close knowledge gaps in hardwood management and provide useful information for non-industrial private forest (NIPF) landowners. It is so important to target NIPF landowners because the 350 million acres of timberland they own will play a large part in the future of the United States timber supply (Haynes 2002). / Master of Science

The main topic of the thesis is the role of timber in the seismic resilience of unreinforced masonry (URM) buildings. The research addressed both existing timber components that can be encountered in URM buildings and timber-based retrofit solutions. The work presented herein can be split into two main phases. In the first part of the research, the in-plane behavior of traditional wooden floors was analyzed by means of numerical static and dynamic simulations. Modelling strategies with different refinement levels were proposed and implemented to assess diaphragm in-plane strength and flexibility. Modelling was undertaken considering as-built diaphragms first and was then extended to diaphragms retrofitted by means of timber-based techniques. The influence of diaphragm construction details on their in-plane response was evaluated and timber-based retrofitting solutions were observed to be effective in mitigating in-plane diaphragm flexibility and in increasing in-plane diaphragm strength. The second part of the PhD work was dedicated to investigate new retrofit solutions for URM buildings based on the use of engineered timber panels mechanically connected to the masonry. The first step saw the experimental testing of different types of timber-to-masonry connections considering both screw-type fasteners and adhesive anchors. In the second stage, full-scale masonry walls were tested in the as-built, retrofitted and repaired configurations, highlighting the benefits of the proposed technique on the in-plane response of the masonry walls.

No description available.

<p>The paper, with a brief summary of timber floating in Sweden and also of some previous re-search in this field, contains a study on costs for timber-floating in the river Dalälven located in central Sweden. The public used timber-floating system in Dalälven and the historical background about this activity is described. The study is focused on the total costs for timber-floating in the public open floating system in Dalälven from 1900 to 1970, the year before the timber-floating was definitively closed down. Also the costs for separating the logs of a specific owner when they reached the point where they could be separated from the timber of other owners are analyzed.</p>

Apesar da versatilidade da madeira, seu emprego fica, às vezes, dificultado por não serem totalmente conhecidas as suas propriedades e seu desempenho em diferentes condições de serviço. Neste trabalho, procura-se contribuir para um melhor aproveitamento das espécies tropicais alternativas, em especial no emprego para produção de elementos estruturais de madeira laminada colada, uma vez que o Brasil possui grande potencial dessas espécies, mas ainda sub-utilizadas. Neste contexto, realiza-se a determinação das propriedades físicas, de resistência e de rigidez de algumas espécies e determinam-se também as rigidezes de elementos estruturais obtidos da espécie cujos corpos-de-prova apresentam os melhores resultados. Ensaiam-se vigas montadas com dois tipos de adesivos, duas intensidades de pressão e duas distribuições de lâminas. Adota-se a metodologia experimental recomendada no ANEXO B da NBR 7190:1997 - Projeto de Estruturas de Madeira, da Associação Brasileira de Normas Técnicas (ABNT). Analisam-se os resultados obtidos a partir de conceitos estatísticos. A espécie Cedrinho (Erisma sp) apresentou as melhores respostas, das quais pode-se concluir que os adesivos Cascophen e à base de mamona não influenciaram as propriedades de rigidez das vigas, o mesmo acontecendo para as duas intensidades de pressão, 0,8 MPa e 1,2 MPa. As propriedades de rigidez das vigas de MLC podem ser influenciadas pela distribuição das lâminas ao longo da altura da seção transversal / Despite the wood versatility, its application is, sometimes, difficult because of its properties and performances under differents work conditions are not completely known. The present work seeks to contribute for a better utilization of the alternative tropical wood species, especially in the employment to the production of structural elements of glued laminated timber, once that Brazil has a great potential of these species which are under applicated. In this context, the determination of the physical properties, the strength and the stiffness of some alternative tropical species are realized, and the stiffness of structural elements made of the specie which presented the best results in specimens tests are determinated. Beams are tested with two adhesives classes, two pressure intensities and two ways of lamination. Experimental methods suggested in ANEXO B, NBR 7190:1997 – Timber Structures Design (Brazilian Technical Codes Association) were used. The specie Cedrinho (Erisma sp) presents the best results, and conclusions are made: Cascophen and castor oil adhesives did not influence the beams stiffness properties; the same thing happens for the two pressure intensities, 0,8 MPa and 1,2 MPa. The glulam beams stiffness properties can be influenced by the ways of lamination

As pontes protendidas transversalmente de madeira vêm sendo pesquisadas no Brasil desde o ano 1995, com madeiras de reflorestamento e outros materiais nacionais. Os resultados mostram a viabilidade da utilização desse sistema na construção de pontes de madeira, sejam em vias rurais, urbanas e até mesmo em rodoviárias no país, a fim de viabilizar melhoras ao acesso onde se faz necessário, além de contribuição nos quesitos de segurança estrutural, em função do trafego. Este trabalho tem como objetivos os estudos teórico e experimental de pontes de madeiras protendidas transversalmente com cordoalhas engraxadas, focando, principalmente, a análise do desempenho da ponte e os estudos das influências da temperatura e da umidade no mecanismo de perda de protensão de tabuleiros laminados com madeiras. / Since 1995 Stress-Laminated Timber Bridge built with reforestation wood and other national materials have been researched in Brazil. The results show feasibility to use this system for build timber bridges, in rural and urban roads, and even in federal highways, in order to facilitate access improvements where needed, plus contribution as safe structural depending on the traffic. The aims of this paper is analyze of theoretical and experimental stress-laminated Timber Bridge with wire rope, focusing, mainly, bridges field performance and thermal response and moisture content as influence in stress relaxation in wood lumber slab.

O CLT (Cross Laminated Timber) ou MLCC (Madeira Laminada Colada Cruzada) é um painel compósito estrutural formado por lamelas de madeira unidas com adesivos próprios para uso estrutural, com as camadas montadas de maneira perpendicular à camada anterior. É utilizado como elemento estrutural principal em edificações térreas e multipavimentos por ter características estruturais semelhantes ao concreto armado. Os objetivos gerais deste trabalho foram desenvolver uma metodologia de ensaios para a caracterização estrutural de painéis de MLCC visando a contribuição para a normatização do produto no Brasil e o estudo da rigidez de um painel modelo. Foi fabricado um painel com dimensões estruturais utilizando madeira de Pinus elliotti e adesivo estrutural à base de melamina-ureia formaldeído. Os ensaios mecânicos realizados foram adequados para caracterização estrutural de painéis de MLCC e podem compor uma futura normatização. Os valores de rigidez para o painel avaliado apresentaram módulo de elasticidade abaixo dos especificados pela norma americana ANSI/APA PGR 320 e pela especificação técnica europeia ETA06/0138, porém os módulos de rigidez do rolling shear e de compressão obtiveram valores similares aos recomendados. / The CLT (Cross Laminated Timber) is a structural composite panel formed by wooden slats together with own stickers for structural use, with the layers mounted perpendicular to the previous layer. It is used as the main structural element in single-story buildings with one or more floors for having structural features similar to reinforced concrete. The aims of this study were to develop a test methodology for structural characterization of MLCC panels aimed at contributing to the standardization of the product in Brazil and the study of rigidity of a panel model. A panel with structural dimensions using wood of Pinus elliotti and structural adhesive melamine urea formaldehyde base was manufactured. The mechanical tests were suitable for structural characterization of MLCC panels and can compose a future standardization. The stiffness values reported for the modulus of elasticity panel presented below specified by the US standard ANSI/APA PGR 320 and the European Technical Specification ETA06/0138, but the stiffness of the rolling shear and compression modules obtained similar to recommended values.

Recent studies showed the need for timber connections with high fire performance. Connections of members in timber structures commonly comprise steel connectors, such as dowels, screws, nails and toothed plates. However, multiple studies have shown that the presence of exposed metal in timber connections leads to a poor performance under fire conditions. Replacing metallic fasteners with non-metallic fasteners potentially enhances the fire performance of timber connections. Previous studies showed that Glass Fibre Reinforced Polymer (GFRP) dowels can be a viable replacement for steel dowels and that Densified Veneer Wood functions well as a flitch plate material. However, as the resin matrix of GFRP dowels is viscoelastic, connection creep, which is not studied before, can be of concern. Also no research has been carried out on the fire performance of these connections. Therefore, a study of the creep behaviour and the fire performance of non-metallic timber connections comprising GFRP dowels and a Densified Veneer Wood flitch plate was performed, as is discussed in this thesis. Predictive models were proposed to determine the connection slip and load bearing capacity at ambient and elevated temperatures and in a fire. The material properties and heat transfer properties required for these models were determined experimentally and predictions of these models were experimentally validated. Furthermore, an adjustment of the predictive model of connection slip at ambient temperature allowed approximating the creep of the connection. The material properties, required for the creep model, were determined experimentally and predictions of the model were compared to results of longterm connection tests. The study confirmed that timber members jointed with non-metallic connectors have a significantly improved fire performance to timber joints using metallic connections. Models developed and proposed to predict fire performance gave accurate predictions of time to failure. It was concluded that non-metallic connections showed more creep per load per connector, than metallic connections. However, the ratio between initial deflection and creep (relative creep) and the ratio between load level and creep were shown to be similar for metallic and non-metallic connections.

Este trabalho tem como objetivo apresentar uma análise do comportamento de estruturas em pórtico de madeira levando-se em conta a influência da ação diafragma da cobertura, que será verificada por meio da realização de ensaios em painéis de diafragma e por análise numérica. Além disso, apresenta os procedimentos de cálculo para o projeto de edificações considerando a ação diafragma de cobertura. Fornece informações para a produção de estruturas treliçadas de cobertura em nível industrial, utilizando-se chapas com dentes estampados, com maior controle de qualidade técnica dos projetos e economia de material. / The aim of this work is to analyze the behavior of post-frame of timber structures taking in account the influence of the roof diaphragm action, which will be verified by tests in diaphragm panels and in computational theoretical model. Furthermore, it will be show the design criteria considering the diaphragm action. Also, important information is presented for increase the production of trusses for roofs in industrial scale using metal plate connectors in conjunction with a better control of the technical quality of design and economy of material.