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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.
201

Hodnocení stavu konstrukčního dřeva s užitím technologie odporového vrtání / Evaluation of the condition of structural timber using resistance drilling technology

Dziadková, Aneta January 2022 (has links)
The aim of this master thesis is to summarize the overview about characteristics and properties of timber and about diagnostic methods used for timber structures prospecting. Experimental part is focused on comparison of drill resistance measurement using Rinntech RESISTOGRAPH for samples at different moisture levels. This paper also includes building survey of roof truss of Litomyšl‘s library and structural report of rafter.
202

Stress-Strain Model of Unconfined and Confined Concrete and Stress-block Parameters

Murugesan Reddiar, Madhu Karthik 2009 December 1900 (has links)
Stress-strain relations for unconfined and confined concrete are proposed to overcome some shortcomings of existing commonly used models. Specifically, existing models are neither easy to invert nor integrate to obtain equivalent rectangular stress-block parameters for hand analysis and design purposes. The stress?strain relations proposed are validated for a whole range of concrete strengths and confining stresses. Then, closed form expressions are derived for the equivalent rectangular stress-block parameters. The efficacy of the results is demonstrated for hand analysis applied for deriving the moment-curvature performance of a confined concrete column. Results are compared with those obtained from a computational fiber-element using the proposed stress-strain model and another widely used model; good agreement between the two is observed. The model is then utilized in the development of a new structural system that utilizes the positive attributes of timber and concrete to form a parallel. Timber has the advantage of being a light weight construction material, easy to handle, is environmentally friendly. However, large creep deflections and significant issues with sound transmission (the footfall problem) generally limit timber use to small spans and low rise buildings. Concrete topping on timber sub-floors mitigate some of these issues, but even with well engineered wood systems, the spans are relatively short. In this study, a new structural system called structural boxed-concrete, which utilizes the positive attributes of both timber and reinforced concrete to form a parallel system (different from timber-concrete composite system) is explored. A stress-block approach is developed to calculate strength and deformation. An analytical stress-block based moment-curvature analysis is performed on the timber-boxed concrete structural elements. Results show that the structural timber-boxed concrete members may have better strength and ductility capacities when compared to an equivalent ordinary reinforced concrete member.
203

Stress-Strain Model of Unconfined and Confined Concrete and Stress-block Parameters

Murugesan Reddiar, Madhu Karthik 2009 December 1900 (has links)
Stress-strain relations for unconfined and confined concrete are proposed to overcome some shortcomings of existing commonly used models. Specifically, existing models are neither easy to invert nor integrate to obtain equivalent rectangular stress-block parameters for hand analysis and design purposes. The stress?strain relations proposed are validated for a whole range of concrete strengths and confining stresses. Then, closed form expressions are derived for the equivalent rectangular stress-block parameters. The efficacy of the results is demonstrated for hand analysis applied for deriving the moment-curvature performance of a confined concrete column. Results are compared with those obtained from a computational fiber-element using the proposed stress-strain model and another widely used model; good agreement between the two is observed. The model is then utilized in the development of a new structural system that utilizes the positive attributes of timber and concrete to form a parallel. Timber has the advantage of being a light weight construction material, easy to handle, is environmentally friendly. However, large creep deflections and significant issues with sound transmission (the footfall problem) generally limit timber use to small spans and low rise buildings. Concrete topping on timber sub-floors mitigate some of these issues, but even with well engineered wood systems, the spans are relatively short. In this study, a new structural system called structural boxed-concrete, which utilizes the positive attributes of both timber and reinforced concrete to form a parallel system (different from timber-concrete composite system) is explored. A stress-block approach is developed to calculate strength and deformation. An analytical stress-block based moment-curvature analysis is performed on the timber-boxed concrete structural elements. Results show that the structural timber-boxed concrete members may have better strength and ductility capacities when compared to an equivalent ordinary reinforced concrete member.
204

Some Observations On Seismic Behaviour Of Traditional Timber Structures In Turkey

Er Akan, Asli 01 June 2004 (has links) (PDF)
This thesis is about behaviour of traditional timber structures under lateral loads in Turkey. The timber-framed houses are the products of cultural heritage of people who live in Anatolia. These structures have performed well in earthquakes throughout the history. As a result, this study intends to present the observations on the seismic behaviours of traditional timber buildings with the help of computer-generated models. In this thesis, the general characteristics of timber are examined, the earthquake problem is briefly introduced, its effects on buildings are discussed, current knowledge on the earthquake performance of traditional Turkish timber buildings is presented, and their seismic behaviours are shown by using SAP2000 to help to better understand their behaviours in an earthquake.
205

An investigation of selected mechanical and physical properties of young, unseasoned and finger-jointed Eucalyptus grandis timber

Crafford, Philippus Lodewicus 03 1900 (has links)
Thesis (MScFor)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: South Africa is a timber scarce country that will most probably experience a shortage of structural timber in the near future. In this study the concept of using young finger‐jointed Eucalyptus grandis timber was evaluated for possible application in roof truss structures while the timber is still in the green, unseasoned state. 220 finger‐jointed boards of cross‐sectional dimension 48 x 73 mm and 36 x 111 mm timber, cut from 5‐18 year old Eucalyptus grandis trees were obtained from Limpopo province, South Africa. The boards were manufactured using a polyurethane (PU) adhesive at moisture content levels above fibre saturation point and no drying was performed. The objectives of this study were to determine various mechanical and physical properties of this finger‐jointed product. More specifically (1) to determine the strength and stiffness potential of the product in the wet and the dry condition, (2) to evaluate physical properties such as density, warp, checking and splitting, (3) to evaluate potential indicator properties to be used as structural grading parameters, and (4) to compare the flexural properties to the current SA pine resource and SANS structural grade requirements. The boards were divided into two groups of the same size, which constituted the wet and the dry samples. Each sample was further separated into six different groups for testing the different strength and stiffness properties. The dry group was stacked in a green‐house for nine weeks until equilibrium moisture content was reached. Afterwards selected physical properties such as warp, checking and splitting were assessed. Destructive testing was conducted on the boards and the results were used to determine various mechanical properties. Finally, each board was assessed for density and moisture content (MC) values. The study showed that the young finger‐jointed Eucalyptus grandis timber had very good flexural properties. Both mean modulus of elasticity (MOE) and modulus of rupture (MOR) 5th percentile strength values for wet and dry boards complied with the current SANS 10163‐1 (2003) requirements for grade S7.The values of tensile perpendicular to grain and compression perpendicular to grain strength did not conform to SANS requirements for grade S5. The other strength properties for the wet and dry groups complied with one of the three SANS structural grades. The 5 year old (48 x 73 mm) boards’ showed significantly higher levels of twist and checking compared to 11 year old boards of the same dimension. Only 46.3% of the finger‐jointed products conformed to the density requirements in SANS 1783‐2 (2004) for grade S7. There was a significant difference in density between the three age groups (5, 11 and 18 years) presented in this study. The variation in both MOE and MOR values of the fingerjointed product proved to be significantly lower in comparison to currently used SA pine sources. Based on the results from this study the concept of producing roof trusses from wet, unseasoned and finger‐jointed young Eucalyptus grandis timber has potential. However, additional research on a number of issues not covered in this study is still required for this product including full scale truss evaluations, proof grading, PU adhesive evaluation at elevated temperatures, nail plate load capacity, and the possible need for chemical treatment of the product against Lyctus beetles. / AFRIKAANSE OPSOMMING: Suid Afrika is ‘n land wat waarskynlik ‘n tekort aan strukturele hout sal ervaar in die nabye toekoms. In hierdie studie word die gebruik van jong gevingerlasde Eucalyptus grandis hout vir die moontlike gebruik in dakstrukture, terwyl nat en ongedroog, ondersoek. 220 gevingerlasde planke van deursnit 48 x 73 mm en 36 x 111 mm gesaag van 5‐18 jaar‐oue Eucalyptus grandis bome en afkomstig van die Limpopo provinsie in Suid Afrika, is gebruik. Die produk is vervaardig met poli‐uretaan (PU) lym uit planke met vog inhouds vlakke bo veselversadigingspunt. Die doelwit van hierdie studie was om verskeie meganiese en fisiese eienskappe van die vingerlas produk vas te stel. Meer spesifiek (1) om die sterkte en modulus van elastisiteit (MOE) potensiaal van die vingerlas produk in die nat en droë toestand te analiseer, (2) om die fisiese eienskappe soos digtheid, vervorming, oppervlakbarse en spleting te ondersoek, (3) om potensiële graderingsparameters te evalueer, en (4) om die buigeienskappe van die produk te vergelyk met SA dennehout asook die SANS strukturele graad vereistes. Die planke is verdeel in twee groepe, ‘n nat groep en ‘n droë groep. Elke groep is verder verdeel in ses kleiner groepe soos buig, trek en drukmonsters. Die droë groep was in ‘n kweekhuis geplaas vir nege weke totdat veselversadigingspunt bereik is. Daarna is geselekteerde fisiese eienskappe soos vervorming, oppervlak barse en spleting gemeet. Destruktiewe toetsing is uitgevoer op die planke en die resultate was gebruik om verskeie meganiese eienskappe vas te stel. Laastens is elke plank se digtheid en voggehalte gemeet. Die studie het getoon dat die jong gevingerlasde Eucalyptus grandis hout goeie buigeienskappe het. Beide die gemiddelde MOE en buig sterkte 5de persentiel waardes van die nat en droë groep het voldoen aan die huidige SANS 10163‐1 (2003) vereistes vir graad S7. Die sterkte‐eienskappe van loodregte trekkrag en loodregte druk het nie die vereistes vir SANS graad S5 gemaak nie. Die ander sterkte‐eienskappe van die nat en droë groep het voldoen aan een van die drie SANS strukturele graadvereistes. Die 5 jaar‐oue (48 x 73 mm ) planke het beduidend hoër vlakke van draai‐trek en oppervlakbarste getoon as die 11 jaar‐oue planke van dieselfe dimensie. Slegs 46.3% van die vingerlas produk het voldoen aan digtheidsvereistes vir SANS graad S7. Daar was ‘n beduidende verskil in dightheid tussen die drie ouderdomsgroepe (5, 11 en 18 jaar). Die MOE en buigsterkte‐waardes van die Biligom produk het beduidend laer variasie as huidige SA denne houtbronne getoon. Die resultate verkry in die studie toon dat die konsep om dakkappe te vervaardig van nat, gevingerlasde jong Eucalyptus grandis hout die potensiaal het om suksesvol toegepas te word. Bykomende navorsing oor ‘n aantal faktore wat nie in hierdie studie ingesluit is nie word steeds benodig. Dit sluit in ‘n volskaalse dakkap evaluasie, proefgradering, PU lym evaluasie by hoë temperature, spykerplaat ladingskapasiteit en die moontlike noodsaaklikheid van chemiese behandeling van die produk teen Lyctus kewers, insluit.
206

Análise teórico-experimental de um tabuleiro misto madeira-concreto composto por vigas circulares /

Alcântara Segundinho, Pedro Gutemberg de. January 2005 (has links)
Orientador: José Antônio Matthiesen / Banca: Renato Bertolino Junior / Banca: Antonio Alves Dias / Resumo: O estudo em estruturas mistas é dedicado ao emprego do material madeira-concreto em estruturas de pontes, mais precisamente no seu tabuleiro. No entanto, a aplicação desse material no Brasil não está regulamentada por normas que permitam ao engenheiro civil fazer sua aplicação nas estruturas correntes. Com a proposta de viabilizar o uso desse material madeira-concreto esse estudo vem contribuir com um melhor entendimento do comportamento físico da ligação entre os materiais madeira e concreto. O estudo dessa ligação foi realizado quantificando o módulo de deslizamento em corpos-de-prova do tipo "push-out", vigas T e tabuleiro de madeira-concreto. Os resultados experimentais do módulo de deslizamento obtidos por esses três tipos de ensaios foram comparados com os resultados obtidos teoricamente pelo Eurocode 5 (1993). Também, no seguinte estudo foi feito uma simulação numérica do tabuleiro de madeira-concreto usando um programa para análise estrutural baseado no Método dos Elementos Finitos (MEF). Na conclusão dessa pesquisa verificou-se que o comportamento estrutural desse material misto pode-ser calculado usando o Eurocode 5 (1993) e o Método dos Elementos Finitos (MEF). / Abstract: The study of mixed structures is dedicated to the use of timber-concrete material in bridges' structures, more precisely in its tray. However, the application of this material in Brazil is not regulated by standards that allow the civil engineer to make its application in the current structures. With the proposal to make possible the use of this timber-concrete material this study contributes to understand better the physical behavior of the linking between wood and concrete. The study of this connection was carried through quantifying the slip's module in specimens of "push-out" type, T beams and timber-concrete's tray. The experimental results of the slip's module from these three kinds of tests had been compared with the results obtained theoretically for Eurocode 5 (1993). Also, in the following study it was made a mathematical simulation of the wood-concrete's tray using a numerical analysis' program based on the Finite Elements' Method (MEF). In the conclusion of this research it was verified that the structural behavior of this mixed material can to be calculated using Eurocode 5 (1993) and the Method of the Finite Elements (MEF). / Mestre
207

Rekreační jezdecké středisko / Recreational Riding Resort

Slavíková, Michaela January 2016 (has links)
This final thesis projects an areal of riding center with four objects. The first one is complex of stabels ,the second one is riding hall, , and the last two area family house and litte apartment for accomodation of employeers and visiters. For objects one and two is complete documentation, the other ones are processed as a studie. All the buildings are designed as a timber structure, the ridding hall is created by glue laminated timber girders.
208

Träbjälklag med tung fyllning : Bjälklag framtaget med inspiration av byggteknik från sekelskiftet 1800–1900 / Timber floor with heavy filling : Floor developed with inspiration from building technique from the turn of the 19th century

Af Klintberg, Albin, Åkehag, Jonny January 2017 (has links)
Denna rapport utreder möjligheterna att använda restprodukter som ljudisolering i lägenhetsskiljande mellanbjälklag av trä med spännvidd 6 m. Ett steg mot att uppfylla Sveriges byggindustris nollvision för koldioxidutsläpp är att bygga mer i trä och att återanvända/återvinna restprodukter. Det svenska entreprenadföretaget Skanska har vid sina krossanläggningar ett överskott av material i form av bergkross 0 - 0,2 mm och krossad restbetong. I denna rapport har en prototyp av ett träbjälklag tagits fram med influenser från byggtekniken från sekelskiftet 1800–1900 med avseende på nyttjandet av tung fyllningsmassa som ljudisolering i träbjälklag. Den framtagna bjälklagsprototypen uppfyller de krav som ställts i BBR efter dimensionering enligt Eurokoderna med hänsyn till brand, hållfasthet, svikt och nedböjning. Enligt en simulering i SEAWood, ett verktyg för akustiksimulering som är under utveckling vid RISE Research Institutes of Sweden, uppfylls även kraven på ljudisolering, detta stöds av de analyser som gjorts av mätresultat från liknande bjälklag. Fyllningsmaterialets höga vikt medför att prototypen är ett lågfrekvent bjälklag, detta kombinerat med att simuleringen endast är en indikation på ljudisoleringsegenskaper gör att det kommer krävas praktiska tester för att fastställa prototypens ljudisolerande och dynamiska egenskaper. Den framtagna bjälklagsprototypen är lämplig att prefabricera tack vare en konstruktion med få ingående delar. Att prefabricera bjälklaget har utöver de ekonomiska fördelar det medför stora fördelar ur ett arbetsmiljöperspektiv och är även fördelaktigt ur fuktsynpunkt. För att uppskatta bjälklagets miljöpåverkan gjordes en enklare jämförelse med ett prefabricerat betongbjälklag som visade att utsläppen av koldioxidekvivalenter fram till bruksfasen var mer än dubbelt så stor för betongbjälklaget än för prototypbjälklaget. / This report investigates the possibilities of using residual products as sound insulation in apartment separating timber floors with a span of 6 m. One step towards meeting the Swedish construction industry's zero vision for carbon dioxide emissions is to build more using timber and to reuse/recycle residual products. The Swedish building contractor Skanska has at its quarries a surplus of material in the form of crushed rock of the 0 - 0.2 mm fraction and crushed residual concrete. In this report, a prototype of a timber floor has been produced with influences of construction technology from the turn of the 19 th century regarding the use of heavy filling as sound insulation in timber floors. The developed floor prototype complies with the requirements set in BBR after dimensioning according the Eurocodes regarding fire safety, strength, sagging and deflection. According to a simulation in SEAWood, a tool for acoustic simulation which is under development at RISE Research Institutes of Sweden the requirements for sound insulation are also met, which is supported by analyzes made by comparing with data on similar timber floors. The high mass of the filling material implies that the prototype is a low frequency floor, this in conjunction with the simulation only being an indication of sound insulation properties, it will require practical tests to determine the prototypes sound insulating and dynamic properties. The developed floor prototype is suitable for prefabrication thanks to a design with few components. Prefabrication of the floor has in addition to the economic benefits it brings great benefits from a working environment perspective and is also beneficial from a moisture point of view. To estimate the environmental impact of the timber flooring, a simple comparison was made with a prefabricated concrete floor which showed that carbon dioxide emissions up to the using phase were more than twice that of the concrete floor than for the prototype floor.
209

Environmental governance and implications of small-scale logging: the case of the indigenous groups in the Ampiyacu Basin in the northeastern Peruvian Amazon

De La Rosa Tincopa, Carolina 2009 August 1900 (has links)
Small-scale logging by indigenous people in Amazonia remains little studied despite the importance of this activity to forest communities and its relevance to the implementation of conservation initiatives. Previous studies in the region have given an overview of small-scale logging and the role of local institutions in the management of timber resources. This study provides insight into the local institutions that govern the use of timber resources and the timber extraction practices of indigenous communities in Amazonia. Timber extraction was examined through a regional case study of indigenous people along the Ampiyacu River, an affluent of the Amazon near Iquitos, Peru. An analysis of the actors within and outside of the Ampiyacu Basin involved in timber harvest and the local institutions for regulating access to forest resources provides the context for examination of local arrangements in small-scale logging. Detailed information about local institutional arrangements was collected through a mixture of qualitative methods, including archival research, focus groups, structured interviews, and direct observation. An analysis of timber practices and the sustainability thereof in extraction areas for the 13 villages of the region allowed a characterization of small-scale logging practices and revealed the most relevant factors in timber extraction strategy and economics. Local arrangements were explained by policy, proximity to an urban market, and access to funding. Most loggers are poor, earning less than $ 496/year in cash, although income levels varied widely within type of funding. The higher income loggers are specialists who log more than the permissible quota and have greater access to funding. Timber was the central economic activity of all local residents. The implications of these findings are discussed for local arrangements and future research on small-scale logging by indigenous peoples of Amazonia. / text
210

Seismic Design of Post-Tensioned Timber Frame and Wall Buildings

Newcombe, Michael Paul January 2011 (has links)
Currently there is a worldwide renaissance in timber building design. At the University of Canterbury, new structural systems for commercial multistorey timber buildings have been under development since 2005. These systems incorporate large timber sections connected by high strength post-tensioning tendons, and timber-concrete composite floor systems, and aim to compete with existing structural systems in terms of cost, constructability, operational and seismic performance. The development of post-tensioned timber systems has created a need for improved lateral force design approaches for timber buildings. Current code provisions for seismic design are based on the strength of the structure, and do not adequately account for its deformation. Because timber buildings are often governed by deflection, rather than strength, this can lead to the exceedence of design displacement limitations imposed by New Zealand codes. Therefore, accurate modeling approaches which define both the strength and deformation of post-tensioned timber buildings are required. Furthermore, experimental testing is required to verify the accuracy of these models. This thesis focuses on the development and experimental verification of modeling approaches for the lateral force design of post-tensioned timber frame and wall buildings. The experimentation consisted of uni-direcitonal and bi-directional quasi-static earthquake simulation on a two-thirds scale, two-storey post-tensioned timber frame and wall building with timber-concrete composite floors. The building was subjected to lateral drifts of up to 3% and demonstrated excellent seismic performance, exhibiting little damage. The building was instrumented and analyzed, providing data for the calibration of analytical and numerical models. Analytical and numerical models were developed for frame, wall and floor systems that account for significant deformation components. The models predicted the strength of the structural systems for a given design performance level. The static responses predicted by the models were compared with both experimental data and finite element models to evaluate their accuracy. The frame, wall and floor models were then incorporated into an existing lateral force design procedure known as displacement-based design and used to design several frame and wall structural systems. Predictions of key engineering demand parameters, such as displacement, drift, interstorey shear, interstorey moment and floor accelerations, were compared with the results of dynamic time-history analysis. It was concluded that the numerical and analytical models, presented in this thesis, are a sound basis for determining the lateral response of post-tensioned timber buildings. However, future research is required to further verify and improve these prediction models.

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