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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Combined glued laminated timber using hardwood and softwood lamellas

Muraleedharan, Aishwarya, Markus Reiterer, Stefan January 2016 (has links)
In this thesis, the behaviour of glued laminated timber combined with hardwood and softwood lamallae is investigated. The influence of hardwood in the tension and compression zone, in terms of strength and stiffness is evaluated.The basis of evaluation consists of determining the behaviour of beams with various combinations of hardwood solely in the tension zone along with beams with hardwood in the tension and compression zone. The influence of different amount of hardwood for both cases is studied my means of experimental and analytical methods.Experimental data attained by performing bending tests are evaluated for different combinations made from spruce and oak. By comparing the experimental and analytical data an increase in the strength and stiffness in various combinations is observed and potrayed which varies based on different wood species.
2

Estudo de emendas dentadas em Madeira Laminada Colada (MLC): avaliação de método de ensaio / not available

Macêdo, Alcebíades Negrão 20 September 1996 (has links)
Este trabalho consiste no estudo teórico e experimental das emendas dentadas em madeira laminada colada (MLC), cujo objetivo principal é avaliar o método proposto no Projeto da Nova Norma Brasileira PNBR 7190 (1996) para a caracterização da MLC, com ênfase às emendas dentadas. As espécies de madeira estudadas foram o Pinus elliottii e o Eucalipto grandis e o adesivo utilizado foi o CASCOPHEN RS-216, à base de resorcinol, produzido pela Alba Química Indústria e Comércio Ltda. A emenda dentada usada no estudo foi a correspondente ao comprimento de 20 mm da DIN 68140, geometria esta adotada pelo parque produtor de MLC no país. Nos ensaios são avaliadas as resistências ao cisalhamento na lâmina de cola, a tração normal à lâmina de cola e a resistência a tração das emendas dentadas. O desempenho das ligações foi avaliado em função da relação entre os valores obtidos nos ensaios com madeira colada e madeira maciça, bem como pelo modo de ruptura dos mesmos. Como conclusão obteve-se que o processo de colagem adotado foi bem sucedido para todos as amostras de caracterização da MLC, independente da espécie de madeira e do tipo de ruptura obtido. O método proposto no Projeto da Nova Norma Brasileira PNBR 7190 (1996) mostrou-se adequado para a caracterização das propriedades de resistência da MLC. / This work consist in the theoretical and experimental study of finger joints in glued laminated timber (GLULAM), with main objective to evaluate the method proposed in the New Brazilian Draft Code PNBR 7190 (1996) to characterization of GLULAM, with emphasis to finger joints. The species of wood studied were the Pinus elliottii and Eucalipto grandis and the adhesive was the CASCOPHEN RS-216, resorcinol-based, produced by Alba Química Indústria e Comércio Ltda. The geometry of finger joint used in the study was the correspondent to DIN 68140, this is the adopted by producer park of GLULAM in the country. In the tests were evaluated the shear resistance of glue lamina, the perpendicular tension resistance of glue lamina and parallel to grain tension resistance of finger joints. The performance of jointing was evaluated as a function of the relation between the values obtained in the tests with glued wood and clear wood, as well as rupture mode. Concluding remarks that gluing process adopted was well successful to all specimens of wood specie and rupture mode. The method proposed by New Brazilian Draft Code PNBR 7190 (1996) is adequate to characterization of the resistance properties of GLULAM.
3

Estudo de emendas dentadas em Madeira Laminada Colada (MLC): avaliação de método de ensaio / not available

Alcebíades Negrão Macêdo 20 September 1996 (has links)
Este trabalho consiste no estudo teórico e experimental das emendas dentadas em madeira laminada colada (MLC), cujo objetivo principal é avaliar o método proposto no Projeto da Nova Norma Brasileira PNBR 7190 (1996) para a caracterização da MLC, com ênfase às emendas dentadas. As espécies de madeira estudadas foram o Pinus elliottii e o Eucalipto grandis e o adesivo utilizado foi o CASCOPHEN RS-216, à base de resorcinol, produzido pela Alba Química Indústria e Comércio Ltda. A emenda dentada usada no estudo foi a correspondente ao comprimento de 20 mm da DIN 68140, geometria esta adotada pelo parque produtor de MLC no país. Nos ensaios são avaliadas as resistências ao cisalhamento na lâmina de cola, a tração normal à lâmina de cola e a resistência a tração das emendas dentadas. O desempenho das ligações foi avaliado em função da relação entre os valores obtidos nos ensaios com madeira colada e madeira maciça, bem como pelo modo de ruptura dos mesmos. Como conclusão obteve-se que o processo de colagem adotado foi bem sucedido para todos as amostras de caracterização da MLC, independente da espécie de madeira e do tipo de ruptura obtido. O método proposto no Projeto da Nova Norma Brasileira PNBR 7190 (1996) mostrou-se adequado para a caracterização das propriedades de resistência da MLC. / This work consist in the theoretical and experimental study of finger joints in glued laminated timber (GLULAM), with main objective to evaluate the method proposed in the New Brazilian Draft Code PNBR 7190 (1996) to characterization of GLULAM, with emphasis to finger joints. The species of wood studied were the Pinus elliottii and Eucalipto grandis and the adhesive was the CASCOPHEN RS-216, resorcinol-based, produced by Alba Química Indústria e Comércio Ltda. The geometry of finger joint used in the study was the correspondent to DIN 68140, this is the adopted by producer park of GLULAM in the country. In the tests were evaluated the shear resistance of glue lamina, the perpendicular tension resistance of glue lamina and parallel to grain tension resistance of finger joints. The performance of jointing was evaluated as a function of the relation between the values obtained in the tests with glued wood and clear wood, as well as rupture mode. Concluding remarks that gluing process adopted was well successful to all specimens of wood specie and rupture mode. The method proposed by New Brazilian Draft Code PNBR 7190 (1996) is adequate to characterization of the resistance properties of GLULAM.
4

Structural behavior of notched glulam beams reinforced by means of plywood and FRP.

Fawwaz, Maha, Hanna, Adnan January 2012 (has links)
Nowadays, timber is widely used in construction industry thanks to its availability and good properties. The use of solid (sawn) timber is not always proper since it is only available up to certain dimensions. Therefore, the so-called Engineered WoodProducts (EWPs) have been introduced to cope with the different design needs of structures. The Glued laminated Timber (glulam) is a type of EWPs that consists of smallsections of timber laminates glued together to form beams and columns. Glulam can be manufactured in almost any size and shape; it can also be tapered or notched. However, notching a beam at its end leads to a stress concentration at the re-entrantcorner of the notch due to the sudden change in the notched beam’s cross section. The concentration of shear and tensile stresses perpendicular to the grain can lead to a catastrophic brittle failure caused by the crack propagation from the notch corner. Crack opening due to tensile stresses perpendicular to grain is the most common failure at the notch corner and it is always taken into design consideration. However,shear component is usually exists and must be also considered in design to guarantee the safety of the structure. Currently, only the normal forces perpendicular to the beam’s axis are considered in the design of the reinforcement in design handbooks. The aim of this thesis was to study the structural behavior of notched glulam beams reinforced by adhered plywood panels and FRP. The carrying capacity of the notched glulam beams at their ends is the main subject of this thesis. In addition, a review of the notched beams design, reinforcements, and analysis theories are included. Experimental series of three point bending tests with notched glulam beams withdifferent configurations of reinforcement was carried out in lab. Deformations and forces were measured both with conventional techniques and with contact-free measurement systems - ARAMIS. On the other hand, a simple model of two dimensional plane stress element has been created of the unreinforced notchedbeam in ABAQUS. The normal and shear stresses were calculated for a horizontalpath of 100 mm in length starting from the notch tip. Afterwards, the mean stresseswere determined for the same path and have been used in calculations. The Mean Stress Approach has been adopted in the hand calculations to calculate the crack length and the failure load according to the ABAQUS model. Accordingly, the failure load was about 40 kN for the unreinforced beams. Also, Eurocode 5 has been used to calculate the failure load which gave a value of 20.2 kN for the unreinforced beams. The average maximum applied load in tests was 30 kN for the unreinforced beams while it reached about two and a half times this value for the CF-reinforced and the plywood-reinforced beams. / Tack vare sina goda egenskaper används trä i byggnadskonstruktioner i allt storeomfattning. Konstruktionsvirke (sågade trävaror) kan dock inte alltid användas pågrund av de begränsade dimensioner som finns tillgängliga. På grund av bl a dettahar ett flertal så kallade engineer wood products (EWP) utvecklats. Limträ är en typav EWP som består av sammanlimmade lameller som bygger upp tvärsnitt i balkareller pelare. Limträ kan tillverkas i nästan godtycklig storlek och form och kan enkeltförses med t ex urtag. Vid urtag i balkändar nära upplag uppstår högaspänningskoncentrationer vid urtagets horn på grund av geometrin. Koncentrationenav normalspänningar och skjuvspänningar kan leda till plötsligt brott på grund avsprickpropagering från urtagets hörn, något som måste tas hänsyn till viddimensionering. Dagens dimensioneringsmetoder är baserade på att man tar hänsyntill enbart normalspänningarna vinkelrät fiberriktningen.Målet med detta arbete har varit att studera beteendet hos limträbalkar med urtag vidupplag som förstärkts med fiberarmering eller plywood. Huvudmålet har varit attbestämma balkarnas bärförmåga, vilket skett genom att genomföra försök med olikakonfigurationer vad gäller förstärkningsmaterial och dess utformning. Vidare harolika dimensioneringsmetoder från litteraturen studerats.Kraft och förskjutning under provningarna uppmättes dels med traditionellamätmetoder, men deformationerna mättes även med beröringsfri metod, ARAMIS.En enkel tvådimensionell finit elementmodell skapades och analyserades i ABAQUSför analys av oförstärkt balk. Normalspänningar och skjuvspänningar beräknades ochmedelspänningarna längs en på förhand definierad sträcka beräknades.Medelspänningskriteriet användes sedan för att uppskatta balkens bärförmåga.Enligt FE-beräkningarna uppskattades bärförmågan för de oförstärkta balkarna till ca40 kN. Provningarna gav ett medelvärde på balkarnas bärförmåga på ca 30 kN,medan de förstärkta balkarna hade en 2,5 gånger högre bärförmåga. Skillnadenmellan FE-beräkningarna och provningarna kan förklaras med den osäkerhet somfinns vad gäller det aktuella trämaterialets egenskaper.Beräkningar enligt Eurokod 5 gav en karakteristisk bärförmåga på 20,2 kN.
5

Emprego de espécies tropicais alternativas na produção de elementos estruturais de madeira laminada colada / Employment of alternative tropical timber species in glued laminated timber structural elements production

Zangiácomo, André Luiz 17 March 2003 (has links)
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
6

Emprego de espécies tropicais alternativas na produção de elementos estruturais de madeira laminada colada / Employment of alternative tropical timber species in glued laminated timber structural elements production

André Luiz Zangiácomo 17 March 2003 (has links)
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
7

Rozhledna / Watchtower

Bednár, Michal Unknown Date (has links)
ABSTRACT The task was to design and assess the supporting structure of the lookout tower. Material steel and wood. The lookout tower is 27.22 m high and decreases in height from the base of the srka. Construction system with continuous columns and horizontal reinforcement.
8

Avaliação do adesivo poliuretano à base de mamona na fabricação de Madeira Laminada Colada (MLC) / Evaluation of the polyurethane adhesive base on castor oil to fabrication of glued laminated timber (GLULAM)

Azambuja, Maximiliano dos Anjos 19 September 2002 (has links)
Este trabalho teve como finalidade o estudo da aplicação de um adesivo alternativo para a fabricação de madeira laminada colada (MLC). Este adesivo, à base de óleo de mamona, apresenta vantagens em relação ao tradicionalmente utilizado, considerando aspectos ecológicos e econômicos. Foram determinados parâmetros adequados para a colagem, e avaliada a compatibilidade entre adesivo e o tratamento com o preservativo hidrossolúvel de Arseniato de Cobre Cromatado (CCA - tipo C) e em madeiras sem o tratamento preservativo, em termos de resistência da linha da cola, por meio dos ensaios de cisalhamento, de tração normal e de tração paralela às fibras, usando a espécie Pinus caribea hondurensis. Com estes parâmetros, foram confeccionadas 12 vigas de MLC, utilizando-se as espécies de reflorestamento Pinus caribea hondurensis e Eucaliptus grandis. Foi avaliado o desempenho estrutural das vigas de MLC, por intermédio do ensaio mecânico de resistência à flexão, objetivando-se analisar a resistência da linha de cola. Os resultados obtidos permitem concluir o bom desempenho do adesivo poliuretano à base de mamona, para a aplicação em madeira não preservada e preservada com OCA tipo-C. A pressão de colagem indicada para laminação das vigas é 0,8% MPa para madeira não tratada, e 1,6 MPa para madeira tratada. Para a fabricação das emendas das lâminas recomenda-se a pressão de colagem igual a MPa, para madeira tratada ou não. / The aim of this work is the study of the use of alternative adhesive for glued laminated timber (GLULAM). This adhesive, based on castor oil, presents ecological and economical advantages in relation of traditionally used. The appropriate parameters for gluing were determined and the compatibility between this adhesive and treatment with the waterbome preservative of chromated copper arsenate (CCA-C) were evaluated through shear tests and tensions tests (perpendicular and parallel to the grain), using the species Pinus caribea hondurensis. With these parameters, were made 12 beams of GLULAM; using the species Pinus caribea hondurensis and Eucaliptus grandis. The structural performance of the beams of GLULAM was evaluated through static bending tests. The results obtained allow concluding the good performance of the adhesive polyurethane based on castor oil, for use in wood not preserved and preserved with CCA type-C. The gluing pressures indicated are 0,8 MPa for non-treated wood, and 1,6 MPa for treated wood. The gluing pressure recommended for finger-joints is 9 MPa, for treated wood or not.
9

En analys av Eurokod 1990 : - användarråd, jämförelser samt en intervjuundersökning

Wennström, Lina January 2008 (has links)
<p>The EN Eurocodes are a new series of standards for construction design in Europe. The development of these codes started originally in 1975 and in present time the progressing work is at the national calibration stage. The goal is to create a common standard for the design of buildings and other civil engineering works throughout Europe and beyond. The purpose is to increase the free circulation of construction products and engineering services. Since the transition to the new standards is getting closer, the constructing engineers and companies will soon stand before great changes. This is why Kadesjös Ingenjörsbyrå AB asked me to do an analysis of the first part of the new standard, i.e. Eurocode 1990, and look at the differences among the existing standards in Sweden and the Eurocodes. The result of this is summarized not only in the report but also in a “User’s manual” which is presented in appendix 1 attached to the report. A limited study of the environmental effects of the transition to Eurocode EN 1990 has also been done. By comparing design calculations of a normal beam in three different materials, steel, concrete and glued laminated timber, one can, for instance, get a general view of how the differences of the two standards affect the required quantity of material. To get an insight of the different opinions that might exist concerning the new standard, a survey based on interviews of a few constructional engineers has been done. There was also discussed if any, and in that case what kind of preparations constructors and design companies are performing to be well prepared when the transition comes.</p>
10

En analys av Eurokod 1990 : - användarråd, jämförelser samt en intervjuundersökning

Wennström, Lina January 2008 (has links)
The EN Eurocodes are a new series of standards for construction design in Europe. The development of these codes started originally in 1975 and in present time the progressing work is at the national calibration stage. The goal is to create a common standard for the design of buildings and other civil engineering works throughout Europe and beyond. The purpose is to increase the free circulation of construction products and engineering services. Since the transition to the new standards is getting closer, the constructing engineers and companies will soon stand before great changes. This is why Kadesjös Ingenjörsbyrå AB asked me to do an analysis of the first part of the new standard, i.e. Eurocode 1990, and look at the differences among the existing standards in Sweden and the Eurocodes. The result of this is summarized not only in the report but also in a “User’s manual” which is presented in appendix 1 attached to the report. A limited study of the environmental effects of the transition to Eurocode EN 1990 has also been done. By comparing design calculations of a normal beam in three different materials, steel, concrete and glued laminated timber, one can, for instance, get a general view of how the differences of the two standards affect the required quantity of material. To get an insight of the different opinions that might exist concerning the new standard, a survey based on interviews of a few constructional engineers has been done. There was also discussed if any, and in that case what kind of preparations constructors and design companies are performing to be well prepared when the transition comes.

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