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Vitásková, Petra. "Studie chování konstrukcí dřevěných lávek." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226646.
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Master’s thesis „Behavioral studies of the timber footbridges structures“ deals with static models of timber footbridges. This thesis mainly consists of the behavioral study of historical timber footbridge in the village of Černvír in Vysočina. Based on the actual design of the bridge a three-dimensional beam model was created. This thesis also includes two contemporary alternatives of timber covered bridges. The individual structural elements were assessed according to the applicable standards. To analyze the model FEM program SCIA Engineer 2012 was used.
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Kolláriková, Simona. "Stavební průzkum a hodnocení stavu konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2021. http://www.nusl.cz/ntk/nusl-433463.
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The diploma thesis deals with building survey of the New synagogue in Velké Meziříčí. It is focused on diagnostics of timber structures using non-destructive and semi-destructive testing methods, such as visual inspection, moisture content measurement, penetration depth of a steel pin measurement and endoscopy. The aim of the thesis is to evaluate the condition of the timber structures according to the results of the building survey.
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Labonnote, Nathalie. "Damping in Timber Structures." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18168.
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Key point to development of environmentally friendly timber structures, appropriate to urban ways of living, is the development of high-rise timber buildings. Comfort properties are nowadays one of the main limitations to tall timber buildings, and an enhanced knowledge on damping phenomena is therefore required, as well as improved prediction models for damping. The aim of this work has consequently been to estimate various damping quantities in timber structures. In particular, models have been derived for predicting material damping in timber members, beams or panels, or in more complex timber structures, such as floors. Material damping is defined as damping due to intrinsic material properties, and used to be referred to as internal friction. In addition, structural damping, defined as damping due to connections and friction in-between members, has been estimated for timber floors. The thesis consists of six main parts. The first part is entitled “Contexts”, and is composed of four chapters. A general overview of the wood material and its structural use in buildings is presented in Chapter 1. Chapter 2 gives a thorough literature review on comfort properties of (timber) floors. Chapter 1 and Chapter 2 serve as justifications for the motivation of this work, expressed in Chapter 3, and the aim of the work, expressed in Chapter 4. The next part “Backgrounds” briefly describes the basic theories used along the thesis, for the analytical studies (Chapter 5), the experimental studies (Chapter 6), and the numerical studies (Chapter 7). The part “State of the art” is a general literature review on damping (Chapter 8). A particular accent is set on the derivation of various damping prediction models. The “Research” part summarizes the original research work. Chapter 9 briefly presents the background and main findings for each study, and Chapter 10 concludes and proposes suggestions for further research. The studies are detailed in four journal papers, which are integrally reported in the “Publications” part. Paper I focuses on the evaluation of material damping in timber beam specimens with dimensions typical of common timber floor structures. Using the impact test method, 11 solid wood beams and 11 glulam beams made out of Norway Spruce (Picea Abies) were subjected to flexural vibrations. The tests involved different spans and orientations. A total of 420 material damping evaluations were performed, and the results are presented as mean values for each configuration along with important statistical indicators to quantify their reliability. The consistency of the experimental method was validated with respect to repeatability and reproducibility. General trends found an increasing damping ratio for higher modes, shorter spans, and edgewise orientations. It is concluded from the results that material damping is governed by shear deformation, which can be expressed more conveniently with respect to the specific mode shape and its derivatives. Paper II deals with the prediction of material damping in Timoshenko beams. Complex elastic moduli and complex stiffness are defined to derive an analytical model that predicts the hysteretic system damping for the whole member. The prediction model comprises two parts, the first related to bending, and the second related to shear. Selected experimental damping evaluations from Paper I are used to validate the model and obtain fitted values of loss factors for two types of wood. The good agreement of the derived model with experimental data reveals an efficient approach in the prediction of material damping. In Paper III, a semi-analytical prediction model of material damping in timber panels is described. The approach is derived from the strain energy method and input is based on loss factors, which are intrinsic properties of the considered materials, together with material properties and mode shape integrals, whose calculation can easily be implemented in most finite element codes. Experimental damping evaluations of three types of timber panels are performed. These are particleboards, oriented strand board panels and structural laminated veneer panels. Fair goodness-of-fit between the experimental results and the prediction models reveals an efficient approach for the prediction of material damping in timber panels with any boundary conditions, knowing only the loss factors and the mode shapes. In Paper IV, dynamic properties of two timber floors are experimentally evaluated by impact method. Each floor uses one specified type of connectors, either screws or nails. A numerical model is developed using constrained degrees-of-freedom for the modeling of connectors. Numerical analyses have been performed, and show good agreement with experimental results. A procedure is written using the commercial finite element software Abaqus to predict material damping from a strain energy approach. Estimation of structural damping is performed as the difference between the experimentally evaluated total damping and the predicted material damping. The contribution from floor members to material damping is extensively investigated, and the needs for better prediction of damping are discussed. Specific details of some aspects of the work are included in the “Appendix” part.
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Magina, Miguel Jorge. "Historic timber roof structures." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/11912.
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Dissertação para obtenção do Grau de Mestre em
Engenharia Civil – Estruturas e GeotecniaThis dissertation covers the study of historic timber roof structures in Transylvania area - Romania, the structures type, its elements and connection variety between them. Procedures to study a structure of this category are approached. It is also referred semi and non-destructive tests that can be done to better understand the present wood characteristics, and potential reparation or strengthening solutions for the structure in case it is necessary. Ultimately a case study is analyzed and some intervention solutions are proposed for a gothic structure type in the nave of Huedin Reformed church.
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Cheng, Alexandra Adelle Hinkel. "Parametric design of timber shell structures." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55140.
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Increasingly complex architectural geometries present new challenges for structural engineers. Collaborative, digital workflows which integrate 3D parametric architectural models with Finite Element Modelling software grant structural engineers a higher degree of geometric versatility and influence during the preliminary design phase. Through integrated parametric design models – also labelled “co-rationalized” – structural engineers may not only easily respond to rapid model variations and unusual assemblies, but also inform the building design from inception.
This thesis presents an example of a project executed in a co-rationalized manner through architectural and structural collaboration, using both digitally-integrated and analog models, for the design and construction of solid timber shells structures using Cross-Laminated Timber (CLT) panels. By exploring a co-rationalized design process, timber engineering details are identified and integrated into the architectural model, and the role of structural engineer takes an active rather than reactionary role in the preliminary design stages.
The result of this process using integrated parametric models was the design, fabrication, and assembly of a folded plate wall prototype and three CLT panels with double curvature. This research demonstrates how collaboration and integrated modeling enables the realization of the architectural versatility that mass-timber has to offer, and the efficacy which co-rationalized design and integrated models can bring to orthodox and unusual structures alike. As a consequence, this research serves as a precedent for structural detailing-based generative architecture and collaborative work in the future.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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André, Alann. "Strengthening of timber structures with flax fibres /." Luleå : Luleå University of Technology, 2007. http://epubl.ltu.se/1402-1757/2007/61/.
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Man, Steve Ka Fai. "Semi-rigid behaviour of plane timber structures." Thesis, City University London, 2004. http://openaccess.city.ac.uk/8410/.
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It is common practice in the analysis of structural frames, to either assume that the joints are pinned or rigid. In fact the real behaviour of a joint is neither pinned nor rigid, and lies somewhere between the pinned and rigid assumption. This is referred to as the semi-rigid behaviour. Semi-rigidity not only refers to the rotational behaviour of the joint as commonly studied, but also in axial and shear actions. The moment distribution between pinned and rigid analysis differs substantially and therefore a more accurate method of modelling the semi-rigid joint is necessary to predict the overall structure response. The level of semi-rigid behaviour varies in different joints due to the material, construction and type of connector. The degree of semi-rigidity can be determined through physical tests. The type of joint for this study is the Metal Plate Connector (MPC) for timber trusses, 6 chosen connector used in residential trusses. An extensive test program was carried out in this study. Four different types of joints of a Queen truss were tested. In addition, the effect of combined loads on the joint characteristics was investigated. The loading arrangement in the tests allowed independent control of the bending moment and axial load. A novel approach is adopted to measure displacement, using high-resolution digital photogrammetry and specially developed software. The data produced gave details of timber movement in cartesian co-ordinates and measurement of plate deformation. From these tests, semi-rigid bending moment and axial stiffness values were determined for use in the theoretical study. An attempt to measure shear stiffness is also presented. Further tests were carried out on full-scale trusses under two different load conditions. The theoretical work comprises two approaches to truss modelling. The first is an automated structural analysis program, which accounts for non-linear semirigid joint characteristics derived from the joint tests using the Foschi power function. The effects of stability and geometrical non-linearity are also implemented into the analysis. The second approach calculates truss response using Finite elements where 2-D planar elements were used to calculate the response of the truss. Parameters for the connection strength are derived from the joint tests. Moment stiffness and axial stiffness values of the connections were determined. Combined load tests showed that there is indeed a measurable effect on joint stiffness and capacity due to combined loads, some of which actually contribute to the stiffness, but also some which are detrimental. There is good correlation between the truss test results and the FE model using semi-rigid joints. However, results of the simpler non-linear frame analysis, did not compare so well, but nevertheless exhibited fundamental characteristics of the truss.
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Griškevičius, Mečislavas. "High Temperature Effect On Resistance Of Timber Structures." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20101119_134602-29128.
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The present dissertation and its main subjects inquires into the pine and oak timber strength property changes-temperature relations. It also explores the behaviour of slender timber elements in axial compression at higher temperatures; and the comparative analysis of obtained results.
The work seeks to accomplish the following major tasks: to obtain test data about the influence of high temperature on the properties of different natural – pine and oak – timber; to investigate the behaviour of slender timber elements under axial compression exposed to fire. Taking into account the investigated real fire effect to correct accordingly the existing in LST EN 1995-1-2 procedure for the fire resistance calculation of timber slender elements in compression.
The dissertation consists of an introduction, five chapters, general conclusions, a list of references, a list of author’s publications on the dissertation subject, and 2 Annexes.
Chapter 1 provides a literature review. It focuses on the publications inquiring into the loss of strength properties by timber at higher temperatures, the fire resistance of timber structures in compression. The chapter ends with the formulation of conclusions and the adjustment of research tasks.
Chapter 2 offers the methodology of the research on strength properties of timber at higher temperatures, and the schemes of the developed testing equipment.
Chapter 3 presents the procedure of the research on the behaviour of slender timber elements... [to full text]Disertacijoje nagrinėjami pušinės ir ąžuolinės medienos stipruminių savybių pokyčių temperatūriniai sąryšiai bei medinių centriškai gniuždomų liaunų elementų elgsena veikiant aukštesnėms temperatūroms. Pagrindiniai tyrimo objektai yra Lietuvos spygliuočių ir lapuočių medienos savybių pokyčiai didėjant temperatūrai ir centriškai gniuždomų liaunų medinių elementų elgsenos veikiant kaitrai eksperimentiniai tyrimai bei rezultatų lyginamoji analizė. Darbe spręsti tokie pagrindiniai uždaviniai: gauti eksperimentinius duomenis apie aukštos temperatūros poveikį skirtingos natūralios – pušinės ir ąžuolinės – medienos savybėms, atlikti centriškai gniuždomų liaunų medinių elementų elgsenos ugnyje tyrimus. Atsižvelgiant į tyrinėtą tikrovišką gaisro poveikį patikslinti esamą EN 1995-1-2 medinių liaunų gniuždomų elementų atsparumo ugniai skaičiavimo metodiką. Disertaciją sudaro įvadas, penki skyriai, bendrosios išvados, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai ir du priedai. Pirmasis skyrius skirtas literatūros apžvalgai. Jame pateikta darbų, kuriuose nagrinėjamas aukštesnės temperatūros veikiamos medienos, stipruminių savybių mažėjimas ir kuriuose pateikiami gaisro sąlygomis gniuždomų medinių elementų laikomosios galios tyrimų rezultatai. Pabaigoje formuluotos išvados ir disertacijos tikslai ir uždaviniai. Antrajame skyriuje pateikta medienos stipruminių savybių aukštesnėse temperatūrose tyrimo metodika ir sukurtų nestandartinių bandymo įrenginių schemos... [toliau žr. visą tekstą]
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Tsai, Pin-Hui. "Seismic evaluation of traditional timber structures in Taiwan." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503662.
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Taiwan is located in a highly seismic zone and the historical “Dieh-Dou” timber buildings, constructed without following any code or standard, are prone to collapse under earthquake. These buildings are unique and represent the culture, heritage and art of Taiwan, therefore need to be preserved while minimizing unnecessary intervention that could damage their authenticity. This research comprises a thorough investigation on the parameters influencing the seismic vulnerability of the Dieh-Dou timber frames in Taiwan, and propose a methodology of assessment and a strategy for strengthening validated through experimental testing and numerical analysis.
After review existing literature and post-earthquake surveys, the failure modes of the buildings are identified, showing that the dislocation of the elements of the frame from the joints is the primary source of damage. An experimental investigation is carried out comprising both rotational and translational tests on full scale joint specimens which, together with a parametric study undertaken with an appropriate FE simulation, demonstrates how both the rotational and translational stiffness of the joints play a key role in defining the behaviour of these structures.
Lateral force, response spectrum, and step-by-step pushover analyses are performed and compared with the post-earthquake survey of two Dieh-Dou buildings seriously affected by the 1999 Chi-Chi earthquake. The results show that the proposed FE modelling can successfully be employed to assess the vulnerability of the frames.
Based on a damage level approach, an assessment methodology is suggested that would allow to optimisation of the strengthening strategy, permitting protection these precious structures from future earthquakes while avoiding unnecessary interventions.
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Bradley, Alistair. "The flood resilience of light frame timber structures." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.698981.
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Morales, Sabogal Agni Amram. "Tall Mass-Timber Building." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78297.
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How can we as design professionals contribute to increase the use of less carbon-intensive materials to build our growing cities?
Cities are experiencing a resurgence in population growth and therefore the building industry ought to attend this demand with sustainable solutions. One way of responding to the growing urban population and increase demand for housing as well as to make efficient use of our limited resources is to increase the density in our cities. Since steel and concrete have high material strengths, we currently use either steel, concrete or composites of them to build skyscrapers. Unfortunately, both of these materials have a large carbon footprint. The design community has the challenge to achieve net-zero emissions buildings by the year 2030, and the efforts now should be focused on using less carbon intensive materials, such as timber.
While cultures around the world have built with wood for centuries, recent technological innovations, such as Cross Laminated Timber (CLT), is allowing for new applications of wood as the main structural material and the potential to use it for large-scale projects. However, as expected with a new building material some constrains have still to be overcome.
For my thesis, I desired to explore this issue through the design of a tall building using mass timber as its main structural material. Engineered timber is here, the future is bright!Master of Architecture
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Mohamed, Ahmed S. "Photogrammetric and stereo vision techniques for evaluating material properties in timber and timber-based composite structures." Thesis, Edinburgh Napier University, 2016. http://researchrepository.napier.ac.uk/Output/462281.
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A fundamental requirement for efficient use of a glulam beam is an accurate knowledge of its mechanical behaviour and the material properties characterising that behaviour. It becomes extremely important to obtain accurate measurements of material properties ofglulam, but this can be challengeable, especially for commonly used properties, such as the modulus of elasticity and shear modulus. Experiment testing is the way to determine elastic properties, however, the problem of experimentally determining appropriatevalues of these properties for timber-based composite is not as simple and straightforward as in isotropic materials, and care must be taken in the experimental methods used in determining their values. There is a need to develop an appropriate method in order to evaluate these properties. Unlike the traditional methods in whichcontact devices such as inclinometers or linear variable differential transducers are used to identify the material properties of glulam by utilizing their measurements of displacements and rotations at specific points, the optical methods provide an efficient and accurate approach for measuring these properties at multi-location so that more regions of interest can be monitored simultaneously without contact. Moreover, the traditional devices are limited to give measurements in one or two dimensions whereas the optical methods can be used to gain measurements in three dimensions. Although the optical techniques were successfully applied to different structural applications, little work has been done on the area of evaluating material properties of timber, especially modulus of elasticity and shear modulus. Therefore, the primary motivation of this project will be allocated to evaluate those properties utilizing the stereo vision approach. This thesis describes the research work in which a stereo camera system combined with a photogrammetric approach was proposed to evaluate material properties of timber and timber-based composite joists. A series of experiments were conducted to investigate the applicability of the approach to evaluate different material properties of glulam beams under different types of tests, including the torsion and the compression. Remarkable findings were obtained which might help for developing an outline for a future research programme in the field of evaluating material properties of glulam, allowing investigating the relationship between these properties. The results also showed that the optical system not only allowed assessing performance and reliabilityof the traditional sensors, but also allowed monitoring the deformation of the samples at various locations by providing more information which would not be possible to obtain using the traditional techniques.
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Janols, Henrik. "Communicating long-span timber structures with 3D computer visualisation /." Luleå, 2005. http://epubl.luth.se/1402-1757/2005/30.
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D'Amico, Bernardino. "Timber grid-shell structures : form-finding, analysis and optimisation." Thesis, Edinburgh Napier University, 2015. http://researchrepository.napier.ac.uk/Output/9833.
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This thesis aims to provide a set of tools for analysis and design of free-form timber grid-shells. It provides a brief introduction on the relationship between shape and structural behaviour of grid-shells, followed by an introduction to actively-bent structural systems. The design issues are then individuated and three main themes are defined, namely: Form-finding, Structural Analysis and Optimisation. The development and use of a numerical framework, based on a six Degree-of-Freedom (DoF) co-rotational beam-element in conjunction with the Dynamic Relaxation method, has formed the basis, on which a unified procedure for the Form-finding and Structural Analysis tasks are denied. A two-step analysis procedure allows seeing a target shape for the grid-shell with the aid of a reference surface, whilst taking into account the effect of internal (bending) reactions on the final geometry. Coupling constraints are numerically simulated by development of a single-node cylindrical joint. An algorithm for grid cutting (mesh manipulation) is described, as well as a modified co-rotational beam-element, based on assumption of 'equivalent' bending stiffness. The modified formulation allows taking into account the change in stiffness of the double-layer members, when passing from the Form-finding to the analysis of the structure under working loads, by simply seeing a dimensionless parameter. A numerical framework for optimisation of the members' cross-section is then introduced. The optimisation problem is decomposed in two main sub-problems, to be separately solved by iterative techniques: the seeking of an ‘allowable' thickness, for the laths under bending action, is pursued with a procedure based on Newton-Raphson method, whilst: a local-search approach is used to find (for a given load configuration) the optimal variation in thickness of the composite cross-section. The proposed methods are validated by several numerical and full-size experimental tests, as well as comparison with the corresponding analytical solution, where available.
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Janols, Henrik. "Communicating long-span timber structures with 3D computer visualization." Licentiate thesis, Luleå tekniska universitet, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18673.
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One of the reasons for the low amount of timber in construction is a general lack of knowledge about timber engineering and how timber can be used to its full advantage. In this thesis the focus is 3D computer visualisation (3D VIZ) of non-residential long-span timber structures, used for storage, industry and sports where 3D VIZ is defined as a process where a 3D-model is enhanced with environmental information e.g. texture maps and realistic light effects. An area of interest is the possibilities to increase timber construction through communicating the aesthetical properties of an exposed timber structure through using 3D VIZ. The aim of this exploratory study is to develop a foundation for future theory building through analysing the construction process and its use of communication media with respect to communication theory and media richness. The study further proposes how the communication process of long-span timber structures can be enhanced by using 3D VIZ and identifies connections between the construction process, participants and project classification. In this thesis two major research strategies have been utilised, a case study and a survey. The first research strategy includes a cross-industry learning research setting, using two case studies, applied and analysed regarding industrial design and architecture. The case studies suggest that a practice of concurrent engineering (CE) in construction and frequent use of 3D-computer visualisation by integrated product teams (IPT) can help to enhance the aesthetical value of the final building. The case studies also confirm that 3D VIZ is useful as a communication tool in the construction industry and demonstrate that using 3D VIZ during the planning process affects the image of the final result created by those involved. The second research strategy includes an Internet-based survey where the usefulness of 3D VIZ during the construction process is evaluated. The results show that structural complexity, intended viewer and current building phase influence the benefit of 3D VIZ. A number of parameters needed to communicate the aesthetics of timber efficiently, i.e. textures, surface structures, true dimensions and realistic light effects, have been pointed out. The analysis regarding communication theory and media richness indicate that the need for rich media, 3D VIZ with high realism and high level of detail (LOD), is generally higher for external communication compared to internal communication between professionals. The need for rich media is also high in the beginning of every new phase, while the need will decrease in the end of the phase.Godkänd; 2005; 20061221 (haneit)
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Kuai, Le. "Parametrized Finite Element Simulation of Multi-Storey Timber Structures." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-66825.
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With the acceleration of global urbanization trends, more and more intentions are put on multi-storey buildings. As the world leading area of wood construction, European countries started the construction of multi-storey timber building for a decade ago. However, unlike the traditional buildings made of reinforced concrete, the design of wooden high-rise timber buildings would face a substantial amount of new challenges because such high-rise timber buildings are touching the limitations of the timber engineering field. In this thesis, a parameterized three-dimensional FE-model (in ABAQUS) of a multi-storey timber frame building is created. Variable geometrical parameters, connection stiffness as well as boundary connections and applied wind and gravity loads are defined in a Python script to make it possible to analyze the influence of these parameters on the global structural behavior of the studied multi-storey timber frame building. The results and analysis implied that the script successfully worked and was capable to create different complex building geometries in an wasy way for the finite element analysis.
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Svanerudh, Patrik. "Design support system for multi-storey timber structures : Patrik Svanerudh." Luleå : Luleå University of Technology, 2001. http://epubl.luth.se/1402-1544/2001/20/index.html.
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Gerard, Robert Buonomo. "Fire Resistance of Connections in Pre-Stressed Heavy Timber Structures." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2010. http://hdl.handle.net/10092/4337.
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Construction with composite materials has become increasingly popular in contemporary structural design for multi-storey residential, commercial, and industrial buildings. As a composite structure, pre-stressed heavy timber buildings offer sustainable, environmentally-friendly advantages over competing construction technologies utilising structural steel and concrete components. Research at the University of Canterbury is continually investigating the performance and behaviour of this composite heavy timber construction assembly. The following research report provides a fire resistance analysis for pre-stressed heavy timber structures that includes:
• A comprehensive literature review detailing the fire resistance for pre-stressed heavy timber structural components and typical connections; and
• A four-phase series of experiments with epoxy grouted steel threaded rods and proprietary mechanical fasteners to determine the fire resistance properties of steel to wood connections.
Laboratory experimentation includes cold testing to determine connection performance at ambient temperature, oven testing to evaluate heating effects on steel to wood connections, cooled testing to determine the residual strength of connections in minor fires and, finally, furnace testing to generate fire resistance design and analysis equations to be utilised for steel to wood connections.
Recommendations for the fire performance of connections in pre-stressed heavy timber structures are included in the report.
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Ertastan, Evren. "The Performance Of Medium And Long Span Timber Roof Structures: A Comparative Study Between Structural Timber And Steel." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606810/index.pdf.
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ABSTRACT
THE PERFORMANCE OF MEDIUM AND LONG SPAN TIMBER ROOF STRUCTURES: A COMPARATIVE STUDY BETWEEN STRUCTURAL TIMBER AND STEEL
ERTASTAN, Evren
M.S, in Building Science,
Department of Architecture
Supervisor: Assoc. Prof. Dr. Ercüment ERMAN December 2005, 174 pages This thesis analyzes the performance of structural timber and steel in medium and long span roof structures. A technical background about roof structures including structural elements and roof structure types, span definitions, and classification of roof structures are discussed. Roof structures are detailed with traditional and the contemporary forms. The thesis comprises the comparison between structural timber and steel by using structural, constructional and material properties. Structural forms and the performance of timber and steel are discussed. The research also includes the roof structures built with structural timber in Turkey, application, marketing and examples in Turkey are indicated. In the conclusion part the performance criteria of timber and steel are summarized, the researcher has prepared a table to compare the performance of timber and steel. Keywords: Timber, Steel, Roof, Structure, Span
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Er, Akan Asli. "Some Observations On Seismic Behaviour Of Traditional Timber Structures In Turkey." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605023/index.pdf.
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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.
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Björnfot, Anders. "Modular long-span timber structures: a systematic framework for buildable construction /." Luleå, 2004. http://epubl.luth.se/1402-1757/2004/034.
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Wong, Ricky Chin Wey. "Construction time and cost of multi-storey post-tensioned timber structures." Thesis, University of Canterbury. Department of Civil and Natural Resources Engineering, 2010. http://hdl.handle.net/10092/5256.
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The environmentally friendly and high performance multi-storey LVL timber system developed at the University of Canterbury (UC) consisting of post-tensioned frames and shear walls is referred to as the Pres-Lam system. It is possible that this structural system has the ability to increase productivity and reduce construction costs when compared with concrete and steel construction materials. As the Pres-Lam system is a new technology, the actual construction time and cost are still unknown. The outcome of this research will add value to the construction industry and encourage the industry to consider the Pres-Lam system for future projects. Previous research has shown that construction using this type of structural system is feasible for multi-storey buildings. In case study (1), this research revisited the research done for the actual Biological Sciences building under construction at the University of Canterbury based on the latest information available from the UC timber research team. This research compared the construction time and cost of three virtual buildings (Pres-Lam, Concrete and Steel) for Case Study (1).
The research has been able to optimise the performance of the Pres-Lam system having increased open spaces with large column spacing. The proposed fully prefabricated double “T” timber concrete composite (TCC) floor system was used and found to reduce construction time. This has also shown that the LVL components in the Pres-lam system can be fully prefabricated at a factory.
In case study (1), the predicted estimated construction time for the structural system was 60 working days (12 weeks) as compared to the concrete structure which required 83 working days. In the construction time analysis only the construction time of the structural building portion was compared instead of the overall construction time of the building project. The construction cost estimation for the concrete, steel and optimised Pres-Lam overall buildings including claddings and architectural fittings were produced and compared. The construction cost analysis concluded that the construction cost of the Pres-Lam building has been estimated to be only 3.3% more than the steel building and 4.6 % more than the concrete building.
In case study (2), this research evaluated the deconstructability of the Pres-Lam system and found that the Pres-Lam system was potentially a very sustainable building material where 90% of the deconstructed materials can be recycled and reused to construct a new office building at the University of Canterbury. The reconstruction time of the STIC office building has been predicted to be 15 weeks and the estimated cost for the reconstruction to be $260,118. This will be used for future construction planning, monitoring and control.
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Debert, Jolene. "Functional Microwear Analysis of Lithics from British Early Neolithic Timber Structures." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508533.
Full textAbstract:
This thesis is a study of the rectangular timber framed structures of the early Neolithic from Britain. Recent discoveries through both research and developer funded projects have significantly increased the number and variety of these buildings now known, but they are the subject of heated and contentious debate. The key themes of the origins of agriculture, degree and character of mobility, and domestic or ritual use, place these structures at the heart of arguments on the nature and means of transition from the Mesolithic to the Neolithic period. This thesis brings together material from both published and unpublished examples, to examine the date and character of their construction and explore their internal use. The case studies discussed in detail are: Balbridie, Claish, Lockerbie, Warren Field, Lismore field, Pilgrim's Way, White Horse Stone, Yarnton, Llandegai and Parc Bryn Cegin. The ecofactual and artefactual information associated with these structures is evaluated using a variety of spatial and material culture analysis techniques, to interpret the range of ways in which they were utilised and inhabited. In addition, an original functional microwear analysis of the stone tools found in and around the buildings at Pilgirm's Way, White Horse Stone, Yarnton, Llandegai and Parc Bryn Cegin are used to enrich understanding of the diversity of tasks and activities carried out in their vicinity. These case studies from England, Wales and Scotland are set in their proper international context through analogy with comparative structures from Ireland and the Continent. The thesis concludes by re-evaluating the nature of these structures, commenting on the narrow date range of their construction and common aspects of their use as well as patterns of inhabitation and deposition. Importantly, it also highlights aspects of difference and diversity in the case studies. Finally, it makes important recommendations for the standardisation of excavation and sampling strategies, in particular advocating the more systematic use of functional microwear analysis as an appropriate tool with which to investigate key questions surrounding the nature of residence, organisation of tasks and use of timber built structures in the initial Neolithic
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Gikonyo, Joan, and Pierre Modig. "Parameterized and Adaptive Modelling of Mechanical Connections in Timber Frame Structures." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-77189.
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This study investigates the global stiffness of a timer frame structure under wind loading using the finite element method by creating parameterized script files. Of key interest was the accuracy of the global stiffness determined from an adaptive 3D beam model in comparison to a 2D beam model and, the stiffness of a 3D beam model when subjected to different types of bracing in the presence of internal bracing provided by a lift shaft structure. Investigation of contact forces on the surfaces between the fastener and the timber at the connection was carried out and a design check for the specified bolts shear capacity done with respect to Eurocode 5. A 3D adaptive connection was created for a 2D frame model and the stiffness of the structure was studied. A comparison of the maximum displacement of the structure in the x direction, under the same wind loading, spring stiffness and boundary conditions, with a 2D beam structure without the adaptive connection initially showed a difference in the displacement. This implied that the rotational stiffness in the beam model was greater than that of the adaptive connection created. Therefore after altering the rotational stiffness of the beam model to achieve similar displacement as in the adaptive model, the rotational stiffness of the created connection was found to be 33.4 · 106Nm. The study also determined the contact forces generated at the surfaces between the fasteners and the timber using the finite element method to integrate over the surfaces and calculate the forces. The results were generated using the History Output in the step module. The only disadvantage of acquiring the contact forces was that, the contact surface simulation caused larger run times for the model to complete the time step. For the adaptive model it took 18 hours to complete each step. Further investigation into the stiffness of a 3D frame structure was conducted. The model of the 3D structure was created by a parameterized script which makes it easy to change input variables such as number of internal walls, geometry in x-z-plane, number of storeys, cross-sectional dimensions, material properties number of diagonals and location of diagonals. A variety of models with different conditions was analyzed. This showed that stiffness has a major impact on the magnitude of reaction forces and displacements.
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Ching, Ho Yin Ernest. "Truss topology optimization of steel-timber structures for embodied carbon objectives." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127282.
Full textAbstract:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 41-43).
Topology optimization in structural design is still a relatively new tool. Most existing research on truss and frame structures focuses on single material applications, and the developments of ground structure-based topology optimization in multi-material structures are limited. This research presents a truss topology optimization algorithm that designs with a mix of glue-laminated timber (GLT) and steel elements. The motivation behind allowing the choice of both these materials is to utilize the strengths of each material in both tension and compression. In addition, this work seeks to include environmental consideration, by incorporating in the algorithm that timber has a smaller embodied carbon coefficient (ECC) compared to steel. This work uses the ground structure approach to truss topology optimization and designs are generated and compared using (i) a minimum compliance and (ii) a stress-constrained algorithm.
The algorithms are constructed such that both the area and a choice of material is made for each element in the ground structure. Both frameworks use fmincon in MATLAB as the gradient-based optimizer. The Solid Isotropic Material with Penalization (SIMP) interpolation is used to relate elastic modulus and embodied carbon for two materials with respect to normalized density variables. To demonstrate the versatility of this design methodology, designs obtained from different objectives and different constraints are presented and compared. We find that, for minimum compliance objectives, the weight-constrained problem produced all-steel truss solutions, while global warming potential (GWP)-constrained problem produced all-timber truss solutions. These results align with our expectations based on material stiffness properties.
For the stress-constrained problem with minimum GWP objectives, the solutions obtained from two modeling assumptions were compared: (i) with real material stress constraints and (ii) with modified stress constraints, where timber was considered as a compression-only material and steel as a tension-only material. Surprisingly, we find that the solutions obtained with the real stress limits are more polluting than the modified stress limit solutions. While the modified stress solutions placed steel in tension and timber in compression for the most environmentally friendly design, the real stress solutions generally favored steel over timber. This is believed to be caused by the nonlinearities introduced through the SIMP interpolation.
by Ho Yin Ernest Ching.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering
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Carradine, David Marc. "Methodology for the Design of Timber Frame Structures Utilizing Diaphragm Action." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/28652.
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Modern timber frame buildings are a unique combination of ancient carpentry techniques coupled with one of the newest enclosure systems found on construction sites around the world. Contemporary timber frame structures typically utilize structural-insulated panels (SIPs) attached to a timber frame skeleton to create functional, enclosed structures, such as houses, churches and a myriad of retail and industrial buildings. The skeleton contains large wooden members connected using wooden joints held together with wooden pegs or wedges. SIPs consist of a layer of rigid expanded polystyrene insulation covered on one side by oriented strand board and on the other side by oriented strand board, drywall, or some other interior finish. In timber frame buildings, SIPs also serve as diaphragm elements, which are flat structural assemblies loaded by shear forces in the plane of the panel. Current design methodologies for timber frame structures do not formally incorporate the structural benefits of SIPs as diaphragm elements, which contribute significantly to the ability of these buildings to resist lateral loads.
The contribution of this research was to quantify necessary design parameters to enable timber frame designers to capitalize on the significant in-plane strength and stiffness of SIPs when designing timber frame structures to resist lateral loads. Strength and stiffness tests were conducted on three 8 ft (2.44 m) deep and 24 ft (7.32 m) long roof diaphragm assemblies, and two 20 ft (6.10 m) deep and 24 ft (7.32 m) long roof diaphragm assemblies. Data from these tests were collected, tabulated and analyzed according to existing methods typically utilized for post-frame diaphragm testing. Strength and stiffness of timber frame and SIP roof diaphragm assemblies were determined from monotonic test results and a value for Response Modification Coefficient, R, for use with seismic design procedures, was estimated utilizing cyclic test data. Procedures for calculating strength and stiffness of a roof diaphragm based on the strength and stiffness of test panels were presented and incorporated within post-frame diaphragm design methods. Diaphragm-frame interaction analyses were performed utilizing test data from roof diaphragm assemblies that demonstrated the code conformance of members within timber frames subjected to lateral loads. Using roof diaphragm test data and procedures developed for adjustments from the test panel to building roof length, example designs were conducted which confirmed the effectiveness of including SIPs as diaphragm elements for code conforming designs for wind and seismic load resistance of timber frame and SIP buildings.Ph. D.
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Björnfot, Anders. "Modular long-span timber structures : a systematic framework for buildable construction." Licentiate thesis, Luleå tekniska universitet, Byggkonstruktion och -produktion, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26617.
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One of the identified reasons for the low amount of timber construction in Sweden is a general lack of knowledge about timber engineering and how timber can be used to its full advantage. One way for increased timber construction is the development of a cost-efficient and easy to comprehend building system. Efficiency in construction has recently been under hot debate following the success of lean production in the manufacturing industry. Therefore, the attention of construction has been directed towards the manufacturing industry in an attempt to learn successful methods. Three main principles, modularity, lean construction, and buildability, emerge as potentially useful in order to streamline construction. The aim of this research project is to create a knowledge- based framework for long-span timber construction. This framework should be able to store knowledge and experience about timber construction as well as aid in the design and production of buildable timber structures. A buildable structure is here defined as a structure constructed in competition with all other materials and sub-system choices, i.e., by this definition a constructed structure is buildable and therefore competitive. The research is based on a case study of the design and production of long- span timber structures performed at a Swedish design company. The case study includes interviews, and a survey of 60 constructed long-span timber structures. A literature review of the industrialisation principles reveals that modularity has been a key concept in the evolution of the manufacturing industry. Therefore, the long-span timber construction industry should emit a bottom-up view where product modularity guides the construction processes. A systematic framework, Experience Feedback System (EFS), is created to store buildable construction knowledge based on modularity. The EFS is based on two distinct systems; Experience Based System (EBS), and Construction Knowledge Database (CKD), connected by a feedback loop for buildable construction feedback. The EBS utilises neural network theory containing competitive knowledge and experience of long-span timber structures, providing aid in early design. The CKS is based on the Design Structure Matrix (DSM), providing management of innovative construction and aid in detailed design. Due to the adaptability of neural networks and the developed 3-D DSM hierarchy representing the structural system, the systematic framework is potentially useful for the design and development of other types of structures and materials choices in the future.Godkänd; 2004; 20070128 (ysko)
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Custodio, Joao Eduardo Pereira. "Performance and Durability of Composite Repair and Reinforcement Systems for Timber Structures." Thesis, Oxford Brookes University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520921.
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Yung, Willy Chi Wai. "Innovative energy dissipating system for earthquake design and retrofit of timber structures." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30128.
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This thesis presents the results obtained from a preliminary investigation into the potential application of the friction damping concept to wood structures to improve their seismic response. Sliding friction devices which contain heavy duty brake lining pads have been proposed in order to enhance a wood structure's seismic performance. The devices are mounted onto a structure's shearwalls to dissipate seismic energy input during the wall's deformation in an earthquake.
Prototypes of the four friction damping devices were tested to examine their hysteretic behaviour. Conventional full scale, 2.44 x 2.44 m (8 x 8 ft) timber shearwalls, typical of ones used in residential and light-commercial building applications, and ones retrofitted with the friction damping devices were tested on a shake table. Three set of tests were conducted. They involved loading the walls under unidirectional racking, static-cyclic and simulated earthquake loads. Test results from the two types of shearwalls were compared against each other and against the findings from the computer programs SADT and FRICWALL. SADT is a finite elements program which computes the load-deformation behaviour of shearwalls. FRICWALL is an inelastic time-history dynamic model which computes the response time-history of a shearwall under a simulated seismic event.
The cyclic tests of the friction damping devices showed that they exhibited very stable and non-deteriorating hysteretic behaviour. The shake table tests of the full scale timber
shearwalls showed that the friction damped walls were stiffer, can sustain an average of 23.7 % higher racking load and dissipate an average of 42.9 % more energy than the conventional ones before a ductile failure. Failure in the conventional walls was brittle. These results were in agreement with the SADT findings. Under slow cyclic loads, they dissipated more energy, but because their overall hysteretic behaviour was still pinched, they were just as inefficient as the conventional walls at dissipating energy. On the average, their seismic performance was only marginally better than that of the conventional wall, with an average drop of 9.6 % in peak wall deflection. This is far short of the average of 29.5 % computed by FRICWALL. Detailed analysis of the results show that due to bending in the framing members of the shearwall, the load necessary to cause slippage of the friction devices was not achieved until wall deflections in the order of 25.4 mm (1.0 in) was reached. Since only at the peak or near-peak excitation levels of an earthquake did shearwall deflections surpass this magnitude, the devices were not able to contribute to the energy dissipation of the shearwalls during the majority portion of a seismic event.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Jaziri, Samy. "Automate sur les structures temporisée." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN039/document.
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Les systèmes digitaux jouent un rôle croissant dans le bon fonctionnement de notre société.Au delà de la grande diversité de leur domaines d'utilisations, on confie aujourd'hui destâches importantes à des algorithmes. Déjà largement utilisés dans des domaines aussi délicatque le transport, la chirurgie ou l'économie, il est aujourd'hui de plus en plus question defaire de la place aux systèmes digitaux dans les domaines sociaux et politiques :vote électronique, algorithmes de sélection, profilage électoraldotsPour les tâches confiées à des algorithmes, la responsabilité est déplacées de l'exécutantvers les concepteurs, développeurs et testeurs de ces algorithmes. Il incombe aussi auxchercheurs qui étudient ces algorithmes de proposer des techniques de vérifications fiablequi pourront être utilisées à tous les niveaux : conception, développement et test.Les méthodes de vérifications formelles donnent des outils mathématiques pourprévenir des erreurs à chaque niveaux. Parmi elle, le diagnostic d'erreur consiste en lacréation d'un diagnostiqueur basé sur un modèle formel du système à vérifier.Le diagnostiqueur est exécuté en parallèle du système qu'il doit surveiller et prévientun contrôleur si il détecte un comportement dangereux du système.Pour les systèmes modélisés par des automates temporisés, il n'est pas toujours possiblede construire un diagnostiqueur sous la forme d'un autre automate temporisé. En effetles automates temporisés, introduits par cite{AD94} dans les années 90 et largementétudiés et utilisés depuis pour modéliser des systèmes avec contraintes temporelles,ne sont pas déterminisable. Une machine plus puissante qu'un automate temporisé peutcependant être utilisée pour construire le diagnostiqueur d'un automate temporisé commele montre cite{Tripakis02}. L'aboutissement de ce travail de thèse est la constructionautomatique d'un diagnostiqueur pour les automates temporisés à une horloge.Ce diagnostiqueur, dans le même esprit que celui de cite{Tripakis02}, est une machineplus puissante qu'un automate temporisé. La partie~I du manuscrit introduit un cadreformel pour ce type de machine et plus généralement pour la modélisation et ladéterminisation de systèmes quantitatifs. Y est introduit le modèle des automates surstructures temporisés, qui apporte un nouveau point de vue sur la manière de modéliserles systèmes avec variables quantitatives. La partie~II étudie le problème de ladéterminisation des automates sur structures temporises, et plus spécifiquement celuides automates temporisés qui peuvent se traduire dans ce cadre nouveau cadre formel.La partie~III montre comment utiliser les automates sur structure temporisés pourconstruire de manière générique un diagnostiqueur pour les automate temporisés à unehorloge. Cette technique est implémentée dans un outils, DOTA , et comparée à lamachine construite par cite{Tripakis02}Digital system are now part of our society. They are used in a wide range of domainsand in particular they have to handle delicate tasks. Already used in domainssuch as transportation, surgery or economy, we speak now of using digital systemsfor social or political matters : electronic vote, selection algorithms, electoralprofilingdots For task handled by algorithm, the responsibility is moved from theexecutioner to the designer, developer and tester of those algorithms. It is alsothe responsibility of computer scientists who study those algorithms to proposereliable techniques of verification which will be applicable in the design, thedevelopment or the testing phase. Formal verification methods provide mathematicaltools to prevent executions error in all phases. Among them, fault-diagnosis consiston the construction of a diagnoser based on a formal model of the system we aim tocheck. The diagnoser runs in parallel with the real system and emit a warning anytime it detect a dangerous behavior. For systems modeled by timed automata, it isnot always possible to construct a timed automaton to diagnose it. Indeed timed automata,introduce in the nineties by cite{AD94} and widely studied and used since to modeltimed systems, are not determinizable. A machine, more powerful than a timed automaton,can still be used to construct the diagnoser of a timed automaton as it is done incite{Tripakis02}. This thesis work aim at constructing a diagnoser for any one-clocktimed automata. This diagnoser is constructed with the help of a machine more powerfulthan timed automata, following the idea of cite{Tripakis02}. Part~I of this thesisintroduce a formal framework for the modeling of quantitative systems and the study oftheir determinization. In this framework we introduce automata on timed structures,the model used to construct the diagnoser. Part~II study the determinization problemof automata on timed structures, and particularly the one of timed automatadeterminization in this framework. Part~III illustrate how automata on timed structurescan be used to construct in a generic way a diagnoser for one clock timed automata.This technique is implemented in a tool, DOTA , and is compared to the technique usedin cite{Tripakis02}
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Kormendy, Imre, and Mustafa Muwaili. "Timber Shear Wall Analysis : Parameterized Finite Element Modelling." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-77199.
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This paper investigates the linear elastic behavior of timber shear walls under monotonic prescribed displacement. ABAQUS© 16.4-5, is a numerical finite element software used as the primary analysis methodology. Parameterized models are created for two shear wall specimens of different geometry concerning door and window configurations. The shear walls are simulated as solid timber framing which is mechanically connected to gypsum sheathing board through fasteners. The primary findings are the linear elastic shear force distribution of the mechanical joints. Additionally, deformations and reaction forces of the shear walls are determined. The overall horizontal shear wall behavior of each specific wall was also studied in the presence of door and window openings. The simulations indicate there is a clear deformation difference in the behaviors of the two shear walls. Furthermore, the highest shear force values of the fasteners are located around the corners of the openings. The findings are supported by other researcher’s experiments and analytical tests, timber shear wall theory and Eurocode design requirements.
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Vessby, Johan. "Shear walls for multi-storey timber buildings." Licentiate thesis, Växjö University, School of Technology and Design, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-2420.
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Wind loads acting on wooden building structures need to be dealt with adequately in order to ensure that neither the serviceability limit state nor the ultimate limit state is exceeded. For the structural designer of tall buildings, avoiding the possibly serious consequences of heavy wind loading while taking account at the same time of the effects of gravitation can be a real challenge. Wind loads are usually no major problem for low buildings, such as one- to two-storey timber structures involving ordinary walls made by nailing or screwing sheets of various types to the frame, but when taller structures are designed and built, serious problems may arise.
Since wind speed and thus wind pressure increases with height above the ground and the shear forces transmitted by the walls increase accordingly, storey by storey, considerable efforts can be needed to handle the strong horizontal shear forces that are exerted on the bottom floor in particular. The strong uplift forces that can develop on the wind side of a structure are yet another matter that can be critical. Accordingly, a structure needs to be anchored to the substrate or to the ground by connections that are properly designed. Since the calculated uplift forces depend very much upon the models employed, the choice of models and simplifications in the analysis that are undertaken also need to be considered carefully.
The present licentiate thesis addresses questions of how wind loads acting on multi-storey timber buildings can be best dealt with and calculated for in the structural design of such buildings. The conventional use of sheathing either nailed or screwed to a timber framework is considered, together with other methods of stabilizing timber structures. Alternative ways of using solid timber elements for stabilization are also of special interest.
The finite element method was employed in simulating the structural behaviour of stabilizing units. A study was carried out of walls in which sheathing was nailed onto a timber frame. Different structural levels were involved, extending from modelling the performance of a single fastener and of the connection of the sheathing to frame, to the use of models of this sort for studying the overall structural behaviour of wall elements that possess a stabilizing function. The results of models used for simulating different load cases for walls agreed reasonably well with experimental test results. The structural properties of the fasteners binding the sheathing to the frame, as well as of the connections between the members of the frame were shown to have a strong effect on the simulated behaviour of shear wall units.
Regarding solid wall panels, it was concluded that walls with a high level of both stiffness and strength can be produced by use of such panels, and also that the connections between the solid wall panels can be designed in such a way that the shear forces involved are effectively transmitted from one panel to the next.
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Aparicio, German Walter Jr. "Holzbau : timber construction and material information exchanges for the design of complex geometrical structures." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59105.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2010.Page 77 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 74).
In a universe made of bits where everything is continuously computing and nature itself is processing information everyday, what is it that our materials compute? Specifically, what are the bits of information registered within timber? More importantly, in this universe made of bits how do we design using this information and how do we imagine new buildings? This thesis explores the use of wood as a natural material in the design and construction of complex geometrical timber structures by capturing the natural curvature found in timber into digital data and building a framework for surface timber mapping as a design method. Key results include a detailed framework for translation, method for timber mapping and a prototype utilizing this method. Future steps include growth of timber structures and the use of living material in combination with typical timber construction methods for the design and construction of future buildings.
by German Walter Aparicio Jr.
S.M.
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Tomoi, Masatoshi. "Reliability-based design for Japanese timber structures using Canadian S-P-F dimension lumber." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30106.
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Reliability levels of Japanese 2x4 wood frame structures were evaluated using lumber property data derived from evaluation of Canadian Spruce-Pine-Fir dimension lumber. The evaluations were made using the "Standard for Limit States Design of Steel Structures (Draft)", which was newly published by the LRFD Subcommittee of Architectural Institute of Japan, and In-Grade Data obtained by a Canadian Wood Council research project. These analyses were implemented using the computer program "RELAN" developed by Dr. R.O. Foschi at UBC and Monte Carlo simulations. Reliability levels of current Japanese 2x4 wood frame structures were also evaluated. Recommendations were made to encourage the application of limit states design into existing Japanese design methods.Forestry, Faculty of
Graduate
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Berjaga, Moliné Xavier. "Case-based diagnosis of batch processes based on latent structures." Doctoral thesis, Universitat de Girona, 2013. http://hdl.handle.net/10803/126303.
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The aim of this thesis is to present a methodological approach for the automatic monitoring of batch processes based on a combination of statistical models and machine learning methods. The former is used to model the process based on the relationships among the different monitored variables throughout time, while the latter is used to improve the diagnosis capabilities of the system. Statistical methods do not relate faulty observations with its root cause (they only list the subset of variables whose behaviour has been altered) and they lack of learning capabilities. By using case-based reasoning (CBR) for the diagnosis, faulty observations can be associated with more significant information (like causes). Statistical models also provide a new representation of the observations, on an orthogonal basis, that improves the use of the distance-based approaches of the CBR, giving a better performanceL'objectiu d'aquesta tesi és la de presentar un mètode automàtic per al monitoratge dels processos per lots basat en la combinació de models estadístics i mètodes d'aprenentatge automàtic. El primer s'utilitza per modelar el procés mitjançant les relacions més significatives entre les variables mesurades al llarg del temps, mentre que el segon s'utilitza per millorar la capacitat de diagnosi del sistema. Els mètodes estadístics no relacionen una observació amb falla amb l'origen d'aquesta al mateix temps que no tenen capacitat d'aprenentatge. El fet d'utilitzar raonament basat en casos per a la diagnosi permet relacionar les observacions amb falla amb informació més significativa (com seria la causa de la falla). Els models estadístics també proporcionen una nova representació de les observacions, en una base ortogonal, que facilita l'aplicabilitat dels mètodes basats en distàncies del raonament basat en casos, tot millorant-ne els resultats obtinguts
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Thompson, David R. "An expert system for the preliminary design of single storey non-domestic timber roof structures." Thesis, University of Brighton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278946.
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Bui, Tuan Anh. "Experimental and numerical uncertain vibration analysis of multilayered timber structures assembled using compressed wood dowels." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0202.
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Cette thèse présente une étude expérimentale et numérique sur les aptitudes en service en ce qui concerne le comportement vibratoire de planchers réalisés en bois d’ingénierie sans colle (AFEWP), à savoir les poutres en bois lamellé sans adhésif (AFLB) et les panneaux en bois lamellé-croisé sans adhésif (AFCLT), assemblés par des tourillons en bois densifié (CWD). Les analyses modales expérimentales ont été réalisées en conditions libres-libre à l'aide d'un marteau instrumenté. Les fréquences naturelles, les modes propres et les coefficients d'amortissement ont été évalués expérimentalement. De plus, des poutres en bois lamellé-collé similaires ont été fabriquées et testées à des fins de comparaison. Un modèle EF 3D a été développé et validé par comparaison avec des données expérimentales, puis utilisé pour prédire le comportement vibratoire d'un système de plancher à grande échelle réalisé avec un panneau AFCLT mesurant 4,5 m x 5,5 m. Une étude paramétrique a été réalisée en utilisant le modèle EF pour identifier les paramètres qui influent sur la rigidité et les fréquences propres du plancher. Les résultats obtenus ont été analysés au regard des critères de conception exigés par Eurocode 5 en ce qui concerne le confort vibratoire des planchers bois. Un modèle EF simplifié a ensuite été développé pour réduire les coûts de calcul. Le niveau de variabilité des résultats des AFEWP a été également étudié et discuté. La variabilité numérique des fréquences des AFEWP a été étudiée en utilisant la méthode MSP (Modal Stability Procedure). Les résultats de la méthode MSP ont d'abord été comparés aux résultats EF dans le cas nominal. Les résultats statistiques (valeur moyenne, écart type, coefficient de variation et distribution) obtenus par la méthode MSP ont été confrontés aux résultats de simulation directe de Monte Carlo ainsi qu’aux données expérimentales. Une estimation rapide des erreurs entre la méthode MSP et la simulation directe de Monte Carlo a été développée. Enfin, la variabilité (moyenne et écart-type des fréquences) du comportement vibratoire du système de plancher à grande échelle a été étudiée en utilisant la méthode MSPThis study presents an experimental and numerical investigation on the vibrational serviceability performance of novel adhesive free engineered wood products (AFEWPs), namely adhesive free laminated timber beams (AFLB) and adhesive free cross-laminated timber panels (AFCLT), assembled through thermo-mechanically compressed wood dowels (CWD). The experimental modal analyses were carried out under free-free conditions using a hammer impact. Natural frequencies, mode shapes, and damping ratio were assessed experimentally. In addition, similar glued timber beams (conventional glulam) were manufactured and tested for comparison purpose. A 3D FE model was developed and validated by comparison against experimental data and then used to predict the vibrational behavior of a realistic flooring system made with AFCLT panel measuring 4.5 m x 5.5 m. A parametric study was performed on the FE model to maximize the floor stiffness. The predicted FE results were discussed with regard to the Eurocode 5 vibrational serviceability design requirements showing acceptable vibrational performance. A simplified FE model was then developed to reduce computational cost. The variability level of the results for the AFEWPs was also studied and discussed. The numerical variability of frequencies of the AFEWPs was investigated based on the development of the Modal Stability Procedure (MSP). The MSP result was first compared with the FE result in the nominal case. Then, the statistic results (mean value, standard deviation, coefficient of variation and distribution) obtained from the MSP were compared with the results from the classical method (direct Monte Carlo simulation) and experimental results. A quick error estimation between the MSP and the direct Monte Carlo simulation was developed. Finally, the mean and standard deviation of the frequencies of the realistic AFCLT flooring system were predicted by the MSP
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Vessby, Johan. "Analysis of shear wallsfor multi-storey timber buildings." Doctoral thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-11489.
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This doctoral thesis addresses questions of how wind loads acting on multistoreytimber buildings can be dealt with by structural design of such buildings.The conventional use of sheathing either nailed or screwed to a timberframework is considered, together with other stabilizing structures such ascross-laminated timber panels.The finite element method was employed in simulating the structuralbehaviour of stabilizing wall units. A series of studies was carried out of walls inwhich the sheathing was nailed to a timber frame. Different structural levelswere studied starting with modelling the performance of single sheathing-toframingconnections, to the use of models for studying the overall structuralbehaviour of walls. The results of calculations using models for simulation ofwalls subjected to different loading agree reasonably well with experimentalresults. The structural properties of the connections between the sheathing andthe frame, as well as of the connections between the members of the frame,were shown to have a substantial effect on the simulated behaviour of shearwall units. Both these types of connections were studied and described inappended papers.Regarding cross-laminated timber wall panels, it was concluded that walls witha high level of both stiffness and strength can be produced by the use of suchpanels, and also that the connections between the solid wall panels can bedesigned in such a way that the shear forces involved are transmitted from onepanel to the next in an efficient manner.Other topics in the thesis include the properties of connections between shearwalls and the rest of the building. Typically high tension forces occur at specificpoints in a timber structure. These forces need to be transmitted downwards inthe structure, ultimately connecting them to the substrate. A lap-joint that maybe used for this purpose has been studied using generalized Volkersen theory.Finally the maximum capacity of a conventional rail to substrate connection hasbeen examined using linear and nonlinear fracture mechanics.
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Sjödin, Johan. "Steel-to-timber dowel joints : Influence of moisture induced stresses." Licentiate thesis, Växjö University, School of Technology and Design, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-1286.
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Joints are critical parts of timber structures, transmitting static and dynamic forces between structural members. The ultimate behavior of a loaded building depends strongly on the structural configuration and the capacity of the joints. The collapse of a whole building or less extensive accidents that may occur is usually starting as a local failure inside or in the vicinity of a joint. Such serious failures have recently occurred in our Nordic countries. Especially the collapse of two large glued laminated timber structures clearly indicates the need of an improved joint design. The trend toward larger and more complex structures even further increases the importance of a safer design of the joints.
An aim of this partly experimental and partly numerically based thesis has been to investigate if steel-to-timber dowel joints are affected by moisture-induced stresses. The experimental results showed that the load-bearing capacity of the joints is reduced by such a moisture influence. Most of the decrease in load-bearing capacity observed was found in joints initially exposed to restrained shrinkage deformations caused by the presence of dowel fasteners in the joint area. The load-bearing capacity was, however, also found to decrease in joints exposed to an initial decrease in moisture without any fasteners present in the specimens during storage before loading. An explanation of this unexpected behavior is that moisture gradients cause tensile stresses. It is shown by numerical simulations that the moisture-induced stresses are so large that they may have a considerable influence on the joint behavior.
Use of contact-free measurement methods, used in some of the experimental tests, was in many ways found to be superior to traditional measurement techniques, but was also found to be a valuable complement to the numerical analysis performed. From numerical results obtained in combination with results from contact-free measurements several observations of considerable interest were made. For dowel-type joints loaded in tension parallel to the grain a strongly non-uniform strain distribution was found in the joint area. It was further observed that the shear and tensile strains were concentrated close to the fasteners in the joint area. These concentrations will influence the failure mode of the joint. A general observation was that the larger sized joints failed in a brittle manner.
Keywords: constraint stresses, contact-free measurement, dowel-type joints, humidity variations, moisture-induced deformations, timber structures
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Zangiácomo, André Luiz. "Emprego de espécies tropicais alternativas na produção de elementos estruturais de madeira laminada colada." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-26052006-150001/.
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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 transversalDespite 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
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Fischbacher, Gordon Anderson. "Diagnosis and modelling of optically thick structures in the lower solar atmosphere." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366870.
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Franzoni, Lorenzo. "Mechanical behavior of regularly spaced Cross Laminated Timber panels : Modeling and experimental validation in ambient and fire conditions." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1113/document.
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Les panneaux en bois lamellé croisé (en anglais CLT - Cross Laminated Timber) sont des éléments de structure composés de couches en bois collées entre eleese et empilées de façon croisée. Chaque couche est composée de planches en bois juxtaposées et généralement non collées sur leur chants. Dans cette thèse, nous étudions l'influence sur le comportement mécanique des espacements entre planches des panneaux avec une approche par modélisation et expérimentation. Les panneaux CLT standard sont considérés comme des panneaux avec des espacements de très faible dimension par opposition aux panneaux avec espacements importants que nous appelons panneaux innovants. Nous modélisons dans un premier temps le comportement en flexion de panneaux standard à l'aide d'un modèle de couche homogène équivalente basée sur des hypothèses simplifiées de la mécanique d'une couche avec chants collés ou non collés. Nous observons un bon accord entre les résultats de notre modélisation et des résultats expérimentaux issus de la littérature. Des études paramétriques sont ensuite réalisés portant sur certaines propriétés des panneaux.Nous avons ensuite réalisé des essais de flexion 4-points sur des panneaux CLT standard et innovants pour quantifier l'influence des espacements sur la réponse mécanique des panneaux. Il se trouve que l'influence des effets de cisaillement transverse sur le comportement élastique et à la rupture augmente avec l'augmentation des vides dans le panneau.Afin de prendre correctement en compte les effets du cisaillement, les CLT espacés sont modélisés comme des plaques épaisses périodiques à l'aide d'un modèle de plaque d'ordre supérieur. Ce modèle a été appliqué à la géométrie des panneaux CLT espacés avec un schéma d'homogénéisation périodique. Des méthodes simplifiées existantes ont également été comparées avec les résultats des essais et le modèle de plaque. De plus, des résultats d'essais de cisaillement dans le plan des panneaux CLT standard issus de la littérature ont été comparés avec nos résultats. La raideur de flexion des CLT espacés peut être prédite avec des méthodes simples existantes, alors que seule la modélisation que nous proposons permet de prédire le comportement en cisaillement transverse et dans le plan. Finalement, des formules analytiques ont été obtenues pour prédire le comportement élastique des CLT espacés. Ces formules donnent une bonne approximation u comportement des CLT espacés et peuvent être utilisées dans le cadre d'une démarche pratique de dimensionnement.Enfin, une étude concernant l'analyse du comportement au feu des panneaux CLT standard est présentée. La comparaison entre des résultats d'essais au feu et une modélisations avancée et simplifiée a permis de proposer une possible amélioration de la méthode de dimensionnement au feu standardCross Laminated Timber (CLT, or crosslam) panels are engineered timber products composed of layers made of wooden lamellas placed side by side, glued on their upperand lower faces and stacked crosswise. In the present thesis, the influence of lateral spaces between lamellas of each layer on the panel’s mechanical response is investigated with modeling and tests. Both configurations of standard panels having short spaces and innovative CLT panels with large spaces are analyzed.As a first approach, the bending behavior of standard crosslam was modeled by means of an equivalent-layer model based on simplified hypotheses on mechanical properties of laterally glued or unglued layers. The good agreement of the predicted behavior with an experiment of the literature finally allowed an investigation on several CLT properties by means of parameter studies.Then, 4-points bending tests on standard and innovative CLT floors were performed in order to quantify the influence of periodic spaces on the panels' mechanical response. It appears that the influence of transverse shear effects on the elastic and failure behavior of spaced CLT increases with the increasing spaces between boards.In order to take into account transverse shear effects, spaced CLT have been modeled as periodic thick plates by means of a higher-order plate theory for laminated plates. This model has been applied to the geometry of spaced CLT with a periodic homogenization scheme. Existing simplified methods for spaced crosslam were compared as well with refined modeling and test results. Moreover, available in-plane shear tests of the literature have been compared to the modeling results. It appears that the bending behavior of spaced CLT can be predicted with simplified existing approaches, while only the more refined modeling can predict the in-plane and transverse shear behavior. Then, closed-form solutions for predicting spaced CLT elastic behavior were derived in order to encourage the application of spaced CLT panels in modern timber construction.One further study within this thesis concerns the analysis of fire-exposed standard CLT floors. The comparison between test results and both advanced and simplified modeling led to a suggestion for a possible improvement the standard fire design model
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Sjödin, Johan. "Strength and Moisture Aspects of Steel Timber Dowel Joints in Glulam Structures : An Experimental and Numerical Study." Doctoral thesis, Växjö universitet, Institutionen för teknik och design, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-2002.
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Joints are critical parts of timber structures, transmitting static and dynamic forces between structural members. The ultimate behavior of e.g. a building depends strongly on the structural configuration and the capacity of its joints. The complete collapse of a building or other less extensive accidents that may occur usually start as a local failure inside or in the vicinity of a joint. Such serious failures have recently occurred in the Nordic countries. Especially the collapses of two large glued-laminated timber (glulam) structures clearly indicate the need of an improved joint design. The trend toward larger and more complex structures even further increases the importance of a safer design of the joints. One aim of this partly experimentally and partly numerically based work has been to investigate if the short term capacity of steel-timber dowel joints loaded parallel to the grain is affected by an initial drying exposure. The experimental results showed that the load-bearing capacity of the joints is indeed reduced by such moisture changes. Moisture induced stresses was mentioned to be the explanation. The key point is that the climates chosen in the present work (20°C / 65% RH and 20°C / 20% RH) are equivalent to service class 1 according to EC5 (Eurocode 5 2004). Thus, EC5 predicts no decrease in load-bearing capacity, in relation to the standard climate used during testing. A decrease in load-bearing capacity in the range of 5-20%, which was found in the present work, is of course not negligible and, therefore, there could be a need to introduce the effect of drying in design codes. Because similar results were also observed for a double-tapered glulam beam, further work should consider timber structures in general. Two numerical methods in order to predict the capacity of multiple steel-timber dowel joints loaded parallel to the grain were tested in the thesis. For the first method, where fracture mechanics (LEFM) concepts were implemented, a good correlation with the experimental results was seen. Also for the second method, where the capacity for a single dowel-type joint as given in EC5 was used as a failure criterion, a good correlation to traditional EC5 calculations of multiple dowel-type joints was seen. One advantage of using numerical methods in design is that the capacity of the joint can be calculated also for cases when the dowels are placed in more complex patterns. From both a structural and an architectural point of view this can be very important. In addition, such numerical methods are effective tools for the structural engineer when considering complicated loading situations in joints, i.e. eccentric loading giving moments in the joint.
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Ceferino, Gloria Esther Urrea. "Pontes protendidas de madeira com cordoalhas engraxadas: perda da protensão." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-07052013-110714/.
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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.
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Baraldi, Lívio Túlio. "Ação diafragma de cobertura aplicada às construções em pórtico de madeira." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-18042016-111714/.
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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.
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Jones, Jennifer Andree. "Clinical diagnosis in nursing : an analysis of knowledge structures and decision making strategies." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316347.
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Pringgana, Gede. "Improving resilience of coastal structures subject to tsunami-like waves." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/improving-resilience-of-coastal-structures-subject-to-tsunamilike-waves(7fd556e2-0202-48ea-a8bf-39582f9c4c7b).html.
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This thesis investigates tsunami impact on shore-based, low-rise structures in coastal areas. The aims are to investigate tsunami wave inundation in built-up coastal areas with reference to structural response to wave inundation, to assess the performance of current design codes in comparison with validated state-of-the-art numerical models and to improve structural design of residential buildings in tsunami risk areas. Tsunami events over the past few decades have shown that a significant proportion of fatalities can be attributed to the collapse of building infrastructure due to various actions of the incident waves. Although major tsunami events have demonstrated the potential catastrophic effects on built infrastructure, current building codes have no detailed or consistent guidance on designing structures in tsunami-prone regions. Furthermore, considerable differences in existing empirical formulae highlight that new research is necessary to appropriately address the particularities of the tsunami-induced forces and structure response into the design standards. In this thesis, numerical modelling methods are used to simulate hydrodynamic impact on shore-based coastal structures. The hydrodynamic simulations were conducted using a novel meshless numerical method, smoothed particle hydrodynamics (SPH), which is coupled with the finite element (FE) method to model structural behaviour. The SPH method was validated with experimental data for bore impact on an obstacle using a convergence study to identify the optimum particle size to capture the hydrodynamics. The FE model was validated against experimental data for plates under transient blast loads which have similar load characteristics with impulsive tsunami-induced bore impacts. One of the contributions of the thesis is the use of a new coupling method of the SPH-based software DualSPHysics and FE-based software ABAQUS. Using SPH particle spacing of the same size as the FE mesh size, enables the SPH output pressure to be directly applied as an input to the structural response model. Using this approach the effects of arrangement and orientation of single and multiple low rise structures are explored. Test cases were performed in 2-D and 3-D involving a discrete structure and multiple structures. The 3-D SPH simulations with single and multiple structures used an idealised coastal structure in the form of a cube with different on-plan orientations (0°, 30°, 45° and 60°) relative to the oncoming bore direction. The single structure cases were intended to study the improvement of the resilience of coastal structures by reducing the acting pressures on the vertical surfaces by changing the structure’s orientation. It was found the pressure exerted on the vertical surface of structure can be reduced by up to 50% with the 60° orientation case. The multiple structure models were conducted to examine shielding and flow focusing phenomena in tsunami events. The results reveal that the distance between two adjacent front structures can greatly influence the pressure exerted on the rear structure. This thesis also demonstrates the capability of SPH numerical method in simulating standard coastal engineering problems such as storm waves impact on a recurve wall in 2-D. The idealised structures were represented as standard timber construction and the finite element modelling was used to determine the corresponding stress distributions under tsunami impact. Following the comparison of the method used in this thesis with commonly used design equations based on the quasi-static approach, large differences in stress prediction were observed. In some cases the loads according to the design equations predicted maximum stresses almost one order of magnitude lower. This large discrepancy clearly shows the potential for non-conservative design by quasi-static approaches. The new model for the simulation of tsunami impact on discrete and multiple structures shows that the resilience of a coastal structure can be improved by changing the orientation and arrangement. The characteristics of tsunami waves during propagation and bore impact pressures on structures can be assessed in great detail with the combined SPH and FE modelling strategy. The techniques outlined in this thesis will enable engineers to gain a better insight into tsunami wave-structure interaction with a view towards resilience optimisation of structures vulnerable to tsunami impact events.
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Brühl, Frank [Verfasser], and Ulrike [Akademischer Betreuer] Kuhlmann. "Ductility in timber structures - possibilities and requirements with regard to dowel type fasteners / Frank Brühl ; Betreuer: Ulrike Kuhlmann." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2020. http://d-nb.info/1218078871/34.
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Somani, Arun K. (Arun Kumar). "A unified theory of system-level diagnosis and its application to regular interconnected structures /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72037.
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System-level diagnosis is considered to be a viable alternative to circuit-level testing in complex multiprocessor systems. The characterization problem, the diagnosability problem, and the diagnosis problem in this framework have been widely studied in the literature with respect to a special fault class, called t-fault class, in which all fault sets of size up to t are considered. Various models for the interpretation of test outcomes have been proposed and analyzed. Among these, four most known models are: symmetric invalidation model, asymmetric invalidation model, symmetric invalidation model with intermittent faults, and asymmetric invalidation model with intermittent faults.In this thesis, a completely new generalization of the characterization problem in system-level diagnosis area is developed. This generalized characterization theorem provides necessary and sufficient conditions for any fault-pattern of any size to be uniquely diagnosable under all the four models. Moreover, the following three results are obtained for the t-fault class: (1) the characterization theorem for t-diagnosable systems under the asymmetric invalidation model with intermittent faults is developed for the first time; (2) a unified t-characterization theorem covering all the four models is presented; and finally (3) it is proven that the classical t-characterization theorems under the first three models and the new result for the fourth model, as mentioned in (1) above, are special cases of the generalized characterization theorem.
The general diagnosability problem is also studied. It is shown that the single fault diagnosability problem, under the asymmetric invalidation model is Co-NP-complete.
As regards the diagnosis problem, most of the diagnosis algorithms developed thus far are global algorithms in which a complete syndrome is analyzed by a single supervisory processor. In this thesis, distributed diagnosis algorithms for regular interconnected structures are developed which take advantage of the interconnection architecture of a multiprocessor system.
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Dimitrova, V., M. O. Mehmood, Dhaval Thakker, B. Sage-Vallier, J. Valdes, and A. G. Cohn. "An ontological approach for pathology assessment and diagnosis of tunnels." ELSEVIER, 2019. http://hdl.handle.net/10454/17643.
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YesTunnel maintenance requires complex decision making, which involves pathology diagnosis and risk assessment, to ensure full safety while optimising maintenance and repair costs. A Decision Support System (DSS) can play a key role in this process by supporting the decision makers in identifying pathologies based on disorders present in various tunnel portions and contextual factors affecting a tunnel. Another key aspect is to identify which spatial stretches within a tunnel contain pathologies of similar kinds within neighbouring tunnel segments. This paper presents PADTUN, a novel intelligent decision support system that assists with pathology diagnosis and assessment of tunnels with respect to their disorders and diagnosis influencing factors. It utilises semantic web technologies for knowledge capture, representation, and reasoning. The core of PADTUN is a family of ontologies which represent the main concepts and relations associated with pathology assessment, and capture the decision process concerning tunnel maintenance. Tunnel inspection data is linked to these ontologies to take advantage of inference capabilities offered by semantic technologies. In addition, an intelligent mechanism is presented which exploits abstraction and inference capabilities. Thus PADTUN provides the world’s first semantically based intelligent DSS for tunnel maintenance. PADTUN was developed by an interdisciplinary team of tunnel experts and knowledge engineers in real-world settings offered by the NeTTUN EU Project. An evaluation of the PADTUN system is performed using real-world tunnel data and diagnosis tasks. We show how the use of semantic technologies allows addressing the complex issues of tunnel pathology inferencing, aiding in, and matching transportation experts’ expectations of decision support. The methodology is applicable to any linear transport structures, offering intelligent ways to aid with complex decision processes related to diagnosis and maintenance.
This work was part of the NeTTUN project, funded by the EC 7th Framework under Grant Agreement 280712.