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DePICT : a conceptual model for digital preservationDappert, Angela January 2013 (has links)
Digital Preservation addresses a significant threat to our cultural and economic foundation: the loss of access to valuable and, sometimes, unique information that is captured in digital form through obsolescence, deterioration or loss of information of how to access the contents. Digital Preservation has been defined as “The series of managed activities necessary to ensure continued access to digital materials for as long as necessary” (Jones, Beagrie, 2001/2008). This thesis develops a conceptual model of the core concepts and constraints that appear in digital preservation - DePICT (Digital PreservatIon ConceptualisaTion). This includes a conceptual model of the digital preservation domain, a top-level vocabulary for the concepts in the model, an in-depth analysis of the role of digital object properties, characteristics, and the constraints that guide digital preservation processes, and of how properties, characteristics and constraints affect the interaction of digital preservation services. In addition, it presents a machine-interpretable XML representation of this conceptual model to support automated digital preservation tools. Previous preservation models have focused on preserving technical properties of digital files. Such an approach limits the choices of preservation actions and does not fully reflect preservation activities in practice. Organisations consider properties that go beyond technical aspects and that encompass a wide range of factors that influence and guide preservation processes, including organisational, legal, and financial ones. Consequently, it is necessary to be able to handle ‘digital’ objects in a very wide sense, including abstract objects, such as intellectual entities and collections, in addition to the files and sets of files that create renditions of logical objects that are normally considered. In addition, we find that not only the digital objects' properties, but also the properties of the environments in which they exist, guide digital preservation processes. Furthermore, organisations use risk-based analysis for their preservation strategies, policies and preservation planning. They combine information about risks with an understanding of actions that are expected to mitigate the risks. Risk and action specifications can be dependent on properties of the actions, as well as on properties of objects or environments which form the input and output of those actions. The model presented here supports this view explicitly. It links risks with the actions that mitigate them and expresses them in stakeholder specific constraints. Risk, actions and constraints are top-level entities in this model. In addition, digital objects and environments are top-level entities on an equal level. Models that do not have this property limit the choice of preservation actions to ones that transform a file in order to mitigate a risk. Establishing environments as top-level entities enables us to treat risks to objects, environments, or a combination of both. The DePICT model is the first conceptual model in the Digital Preservation domain that supports a comprehensive, whole life-cycle approach for dynamic, interacting preservation processes, rather than taking the customary and more limited view that is concerned with the management of digital objects once they are stored in a long-term repository.
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A theory of digital library metadata : the emergence of enriching and filteringAlemu, Getaneh January 2014 (has links)
The ever increasing volume and diversity of information objects, technological advances and rising user expectations is causing libraries to face challenges in adequately describing information objects so as to improve the findability and discoverability of these objects by potential end users. Taking these present metadata challenges into account, this thesis inductively explores and develops overarching concepts and principles that are pertinent within both current standards-based and emerging metadata approaches. Adopting a Constructivist Grounded Theory Method, this thesis conducted in-depth interviews with 57 purposefully selected participants, comprised of practising librarians, researchers, metadata consultants and library users. The interview data was analysed using three stages of iterative data analysis: open coding, focused coding and theoretical coding. The analysis resulted in the emergence of four Core Categories, namely, metadata Enriching, Linking, Openness and Filtering. Further integration of the Core Categories resulted in the emergence of a theory of digital library metadata; The Theory of Metadata Enriching and Filtering. The theory stipulates that metadata that has been enriched, by melding standards-based (a priori) and socially-constructed (post-hoc) metadata, cannot be optimally utilised unless the resulting metadata is contextually and semantically linked to both internal and external information sources. Moreover, in order to exploit the full benefits of such linking, metadata must be made openly accessible, where it can be shared, re-used, mixed and matched, thus reducing metadata duplication. Ultimately, metadata that has been enriched (by linking and being made openly accessible) should be filtered for each user, via a flexible, personalised, and re-configurable interface. The theory provides a holistic framework demonstrating the interdependence between expert curated and socially-constructed metadata, wherein the former helps to structure the latter, whilst the latter provides diversity to the former. This theory also suggests a conceptual shift from the current metadata principle of sufficiency and necessity, which has resulted in metadata simplicity, to the principle of metadata enriching where information objects are described using a multiplicity of users’ perspectives (interpretations). Central to this theory is the consideration of users as pro-active metadata creators rather than mere consumers, whilst librarians are creators of a priori metadata and experts at providing structure, granularity, and interoperability to post-hoc metadata. The theory elegantly delineates metadata functions into two: enriching (metadata content) and filtering (interface). By providing underlying principles, this theory should enable standards-agencies, librarians, and systems developers to better address the changing needs of users as well as to adapt themselves to recent technological advances.
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Inomhusklimat i studentbostad : En studie om det termiska inomhusklimatet på Åkarhagsgatan 1 i VästeråsHellberg, Philip, Wennberg, Linda January 2018 (has links)
Nowadays most people tend to spend a major part of their lives indoors; therefore, the importance of withholding a good internal environment in our buildings is essential. What follows, the thermal indoor climate is strongly influencing the quality and comfort of life in residential areas. This essay will focus on thermal indoor climate situation in a student residence. Based on calculations, measurements and simulations from two different student apartments as well as data collected through a survey, this work will discuss whether the indoor climate complies with the requirements and standards for student housing and what improvement options are available. The survey showed dissatisfaction with the indoor temperature during summer and wintertime. Furthermore, the climate simulation demonstrated the increase in temperature during the summertime, which resulted in a greater dissatisfaction (PPD). Additionally, the calculations made to compare with the climate simulation have also shown that the apartments are getting too hot during summer. IDA ICE logged the relative humidity over a longer period of 1 year, resulting in a range between 5.8% -77.8%. Own measurements such as temperatures, relative humidity, carbon dioxide and exhaust airflows have been set against standards and requirements from authorities and deficiencies of the thermal indoor climate have been mapped. The apartments meet the standard of thermal indoor climate for student housing with one exception -the carbon dioxide content exceeds 1000 ppm in the apartment with the presence of two people. The exhaust airflow in both apartments was lower in our own measurements in comparison to what they were at the OVK protocol from 2014. The exhaust airflow in one apartment had a flow rate of 10 l / s higher than the dimensional flow rate, which indicates imbalance in the system. According to IDA ICE, too high and too low humidity was observed. This may indicate that the apartments do not have a satisfactory sun shading, which plays a significant role in the indoor climate. Using sun shading on all windows could reduce the temperature increase from solar radiation by 50% and the maximum operating temperature could be lowered by 4 degrees in IDA ICE. Using awnings as the sun shading solutions would also lower PPD's high peaks to 10%.
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Byggnadstekniska lösningar för brandskydd på radhusvindarVikström, Matilda, Edlund, Desirée January 2018 (has links)
No description available.
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Jämförande studie av lastnedräkningar för hand och med FEM-programAlniemi, Jamal January 2018 (has links)
No description available.
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Simplified mechanical models for the nonlinear dynamic analysis of elasto-plastic steel structures impacted by a rigid bodyHeng, Piseth January 2017 (has links)
Buildings subjected to impact and explosion are usually studied using large scale and highly nonlinear finite element model which are time-consuming. The first part of the thesis deals with the development of simple and accurate models for evaluating the nonlinear inelastic behaviour of steel frame structures subjected to impact. The research work in this part has produced four simplified models. The first model concerns with a 4DOF model that reproduces the behaviour of the impacted column. The restraining effect from the rest of the structure is modelled by an elastic spring, a head mass and a static load applied at the top of the column. In the second model, the impacted column is then further simplified using a SDOF model. The behaviour of the SDOF model is governed by an analytical force-displacement expressions of the column loaded by a located force. The maximum displacement of the impacted column can also be determined explicitly by adopting an energy-equivalent approach. Afterwards, in an effort to model the whole structure, two finite element models are developed. For these models, a co-rotational super-element that consists of a beam element and two generalized elasto-plastic hinges is obtained by performing a static condensation. An elastic flexible beam element is used in the first finite element model, whereas a rigid beam element is considered in the second one. In these models, inelasticity is concentrated at generalized elasto-plastic hinges which are modelled by combined axial-rotational springs. The behaviour of the hinges is uncoupled in the elastic range while an axial-bending interaction is considered in the plastic range making it possible to reproduce a wide range of cross-sections and joints. In addition, unilateral contact between rigid point masses is considered and the energy loss during impact is accounted by means of a restitution coefficient following Newton’s impact law. Energy-momentum scheme is used to solve the equations of motion produced by these models. The second part of the thesis concerns with the performance of the connectors in composite steel-concrete slabs under explosion. The purpose is to determine residual capacities of the shear connectors after being damaged by explosion using large-scale pull-out and push-out experimental tests and finite element simulations. / <p>QC 20171106</p>
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Considering the flexibility of human resources in planning and scheduling industrial activitiesAttia, El-Awady 05 April 2013 (has links) (PDF)
The growing need of responsiveness for manufacturing companies facing the market volatility raises a strong demand for flexibility in their organization. This flexibility can be used to enhance the robustness of a baseline schedule for a given programme of activities. Since the company personnel are increasingly seen as the core of the organizational structures, they provide the decision-makers with a source of renewable and viable flexibility. First, this work was implemented to model the problem of multi-period workforce allocation on industrial activities with two degrees of flexibility: the annualizing of the working time, which offers opportunities of changing the schedules, individually as well as collectively. The second degree of flexibility is the versatility of operators, which induces a dynamic view of their skills and the need to predict changes in individual performances as a result of successive assignments. The dynamic nature of workforce’s experience was modelled in function of learning-by-doing and of oblivion phenomenon during the work interruption periods. We firmly set ourselves in a context where the expected durations of activities are no longer deterministic, but result from the number and levels of experience of the workers assigned to perform them. After that, the research was oriented to answer the question “What kind of problem is raises the project we are facing to schedule?”: therefore the different dimensions of the project are inventoried and analysed to be measured. For each of these dimensions, the related sensitive assessment methods have been proposed. Relying on the produced correlated measures, the research proposes to aggregate them through a factor analysis in order to produce the main principal components of an instance. Consequently, the complexity or the easiness of solving or realising a given scheduling problem can be evaluated. In that view, we developed a platform software to solve the problem and construct the project baseline schedule with the associated resources allocation. This platform relies on a genetic algorithm. The model has been validated, moreover, its parameters has been tuned to give the best performance, relying on an experimental design procedure. The robustness of its performance was also investigated, by a comprehensive solving of four hundred instances of projects, ranked according to the number of their tasks. Due to the dynamic aspect of the workforce’s experience, this research work investigates a set of different parameters affecting the development of their versatility. The results recommend that the firms seeking for flexibility should accept an amount of extra cost to develop the operators’ multi functionality. In order to control these over-costs, the number of operators who attend a skill development program should be optimised, as well as the similarity of the new developed skills relative to the principal ones, or the number of the additional skills an operator may be trained to, or finally the way the operators’ working hours should be distributed along the period of skill acquisition: this is the field of investigations of the present work which will, in the end, open the door for considering human factors and workforce’s flexibility in generating a work baseline program.
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Stiffness of reverse channel connections at room and elevated temperaturesHeistermann, Tim January 2013 (has links)
A frame structure exposed to fire undergoes two types of changes due to the resulting temperature fields. The first is the thermal expansion of the structural members and the second is the degradation of the material strength and stiffness as temperature rises. Initially the thermal expansion dominates the response and the structural member (beam) is exposed to compressive forces due to restrained expansion, thus precipitating flexural buckling. At higher temperatures the mechanical material properties degrade. This fact, together with the high compressive forces in the bottom flanges of the beam often results in local buckling, followed by the formation of a plastic hinge close to the support region. The combination of transverse loads and the rising temperature leads to the development of excessive deflections in the beam. When temperature rises enough for the bending resistance of the beam to become insufficient, catenary action is introduced. The result is that the beam transitions to a stage where tensile forces appear due to the catenary action. In these different stages of the response of the structure the beam-to-column connection plays a crucial role and its robustness will determine if the structure will be able to maintain its integrity.The robustness of a structure in a fire situation greatly depends on the rotational capacity of the connection region. High rotational capacity is required at elevated temperatures since the steel beams lose their bending stiffness and exhibit increasingly large deflections under constant load. Beam deflections result in increasing rotations at the supports and may lead to collapse due to connection failure. Other possible failure modes may occur in the structural members, for example due to yielding in tension of the beam. The reverse channel has been proposed as a practical alternative to assemble beams to tubular columns. In a simple implementation, the bending moment generated in the joint due to rotation of the beam may be neglected; however, research efforts are being attempted to quantify the level of constraint. The typical arrangement of the connection type consists of a reverse channel with its flanges welded onto the face of concrete-filled tubular columns and the web bolted to the endplate of a beam. Thicknesses and depths of the reverse channel determine the level of rotational restraint at high temperature. The reverse channel has the ability to undergo catenary deformation in the tensile zone due to the applied rotation at the support and similarly it is relatively ductile in the compression zone. Overall, the reverse channel connection response is rather ductile in terms of its ability to undergo large rotational deformation as long as bolt failure is avoided through proper design.Various tests have been performed to study the behaviour of this type of connection such as full scale buildings, sub-frames, isolated joints and individual sections. The aim of these tests was to capture the connection behaviour in relation to other structural components in fire. This thesis focuses on the tests carried out on the connection components and their finite element modelling. A comprehensive parametric study was performed to assess the influence of different parameters on the behaviour of the connection component at elevated temperatures. The results from the finite element analyses have been utilized to validate analytical models that describe the behaviour of this type of connection at ambient and elevated temperature. Insight into the analytical models provides proper background to a structural designer to estimate the initial stiffness and understand the behaviour of the reverse channel in the connection. / En ramkonstruktion utsatt för brand påverkas på två olika sätt av temperaturhöjningen. För det första blir det en längdutvidgning av temperaturhöjningen och för det andra tappar materialet styrka och styvhet med ökande temperatur. Inledningsvis dominerar effekten av temperatur-utvidgningen. Denna leder till tryckande tvångskrafter i konstruktionen vilka kan leda till knäckning.Vid höga temperaturer sjunker materialets styvhet och styrka. Detta kan tillsammans med de höga tryckkrafterna leda till att flytleder bildas vid stöd. De stora tryckkrafterna kan också orsaka knäckning i balken och transversallasterna kan med den minskade styvheten på grund av temperaturhöjning ge upphov till mycket stora deformationer och balkens bärförmåga blir vid tillräckligt höga temperaturer otillräcklig. Vid tillräckligt stora deformationer övergår det statiska verkningssättet från böjning till linverkan. Under denna övergång spelar förbanden mellan balkar och pelare en central roll, och hur dessa klarar att hantera laster och deformationer avgör om hela konstruktionen kan klara belastningen.Hur en konstruktion klarar en brandbelastning beror i hög grad på hur förbanden mellan balkar och pelare klarar rotationer. En stor rotationskapacitet krävs vid höga temperaturer eftersom stålbalkar då har låg bärförmåga och deformationerna kan bli mycket stora även om lasterna är oförändrade. Stora deformationer i balkarna leder till stora rotationer i knutpunkterna vilket kan leda till att förbanden brister och hela konstruktionen kollapsar. Andra möjliga brottmoder kan vara kollaps av balkarna på grund av plasticering under drag. U-profilen har föreslagits som ett praktiskt alternativ för att ansluta balk till pelare. Rotationskapaciteten för ett sådant förband kan bedömas som försumbar, men forskningsinsatser görs för att bestämma den. En föreslagen utformning är att svetsa U-profilens flänsar till den betongfyllda pelaren med slutet tvärsnitt och livet fäst med skruvar i ändplåten på en balk. Rotationsstyvheten vid höga temperaturer kommer att bero på dimensioner på U-profilen. En U-profil har möjligheten att genomgå omvandlingen till linverkan i den dragna delen när den utsätts för ändrotation med den tryckta delen intakt. I allmänhet har ett förband med en U-profil möjlighet att klara stora rotationer under förutsättning att skruvförbandet är utformat på rätt sätt.Ett antal försök har genomförts för att studera hur föreliggande förband kan fungera i en byggnad, en del av en ram, enskilda förband och i tvärsnitt. Försöken har gjorts för att nå förståelse för hur förbandet fungerar tillsammans med andra konstruktionsdetaljer när de utsätts för brandbelastning. Denna avhandling fokuserar på försöken med delar ur förbandet och finit element modellering. En omfattande parameterstudie har gjorts för att förstå hur olika parametrar påverkar förbandets egenskaper vid förhöjd temperatur. Från FE-beräkningarna har analytiska modeller tagits fram som beskriver förbandets egenskaper vid medelhöga och höga temperaturer och dessa ger konstruktören möjlighet att uppskatta den ursprungliga styvheten hos förbandet med U-profil och förståelse för dess uppträdande. / <p>Godkänd; 2013; 20131008 (timhei); Tillkännagivande disputation 2013-11-11 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen, dubbel doktorsexamen LTU och University of Coimbra, Portugal. Namn: Tim Heistermann Ämne: Stålbyggnad/Steel Structures Avhandling: Stiffness of Reverse Channel Connections at Room and Elevated Temperatures Opponent: Professor Darko Beg, Head of Steel Structures, Ljubljana University, Ljubljana, Slovenien Ordförande: Professor Milan Veljkovic, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Vice ordförande: Assistant Professor Rui António Duarte Simões, Civil Engineering Department, University of Coimbra, Coimbra, Portugal Tid: Tisdag den 3 december 2013, kl 09.00 Plats: F1031, Luleå tekniska universitet</p>
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Prefabrication strategies in the timber housing industry : a comparison of Swedish and Austrian marketsNord, Tomas January 2008 (has links)
The functional-based building regulations issued in 1994/95, made it possible to once again build higher buildings with timber structures in Sweden. At the same time there was a need to make the traditional project- oriented construction process more efficient, with prefabricated building systems and products as one possible solution. Since then, a number of timber housing companies have established product strategies and developed system solutions to meet the demands from different markets. In other European countries, changes in rules and regulations have positively facilitated the development of timber building products and systems and established new companies and strategies. Austria is one example, where architecture and technology are in focus, developing different product strategies in the timber housing industry. External factors and their changing, affect the formulation of viable business strategies in the timber housing industry. This dissertation aims to describe and analyse the strategic development of timber housing companies in Sweden and Austria. Strategy theories on the alignment of internal elements and external factors to create competitive advantage are applied in this dissertation. The results are based on empirical data gathered in a multiple case-study with two cases from Sweden and Austria, respectively. Result show that the strategic development of the Austrian timber housing companies was determined by the established conditions in the construction process. Timber structures already had strong positions in specific market segments; hence, the strategic behaviour of timber housing companies progressed with an inside-out approach. The strategic focus was to develop efficient internal processes that focus on design skills, flexible production facilities and on-site assembly resources to improve competitive advantage. The strategic development of the Swedish timber housing companies was based on what was possible from the changes in basic conditions, which partly diverted from the common and shared understanding in the construction process; hence the strategic behaviour of timber housing companies have had an outside-in approach to create competitive advantage. They have developed product platforms of standardised modules or elements and where cooperation with technical and system design complementors have been important to offer competitive timber building system solutions. The results indicate a strong correlation between basic conditions - construction process - firm conduct. Changes in basic conditions will give raise to firm conduct, different from the normative behaviour in the construction process, by firms with resources and capabilities by the changing basic conditions. / Möjligheten att bygga höga byggnader med trästomme i Sverige kom som en följd av införandet av funktionsbaserade byggregler i mitten av 1990-talet. Samtidigt fanns ett behov av att effektivisera den traditionellt projektorienterade byggprocessen där industriellt förtillverkade systemprodukter sågs som en möjlig lösning. Detta utgjorde drivkraften till att ett antal träbyggnadsföretag har skapats och utvecklat produktstrategier och systemlösningar för högre hus i trä. Även i ett europeiskt perspektiv har det skapats ökade möjligheter för träbyggprodukter inom husbyggandet via regeländringar, vilket påverkat företagens strategier. Ett exempel är Österrike där arkitektur och teknik varit förtecken i utvecklandet av olika produktstrategier inom träbyggnadsindustrin. Omvärldsfaktorer och dessas förändring påverkar hur träbyggföretag skapar och utvecklar sina företagsstrategier. Denna avhandling syftar till att beskriva och analysera den strategiska utvecklingen av träbyggföretag i Sverige och Österrike. Avhandlingen har sin teoretiska bas i strategiteorier, där passningen mellan interna och externa förutsättningar ligger till grund för hur företag utvecklar konkurrensfördelar. Resultaten är baserade på data insamlade via en multipel fallstudie där två fall från Sverige respektive Österrike ingick.Resultaten visar att de österrikiska träbyggföretagens strategiska utveckling har skett inom ramen för vad som är givet av den etablerade byggprocessen. Träbyggnader har haft sina givna marknader och företagens strategiska agerande har varit med ett inifrån-ut-perspektiv. Det strategiska agerande har präglats av att utveckla effektiva interna processer med fokus på konstruktionskunnande, flexibla produktionsmetoder och byggplatsåtaganden för att öka konkurrensförmågan. De svenska träbyggföretagens strategiska utveckling har skett inom ramen för vad som är möjligt utifrån de förändrade grundförutsättningarna, och delvis avvikande från normen i byggprocessen. Träbyggföretagen har haft ett utifrån-in perspektiv och utvecklat träbyggsystem baserade på standardiserade modul- eller planelement. Samarbeten med olika projekteringsresurser har varit viktiga för erbjudanden med hetsåtagande.Resultaten visar att det finns ett starkt samband i kopplingen mellan grundförutsättningar - byggprocess - företagsagerande. När förändringar i grundförutsättningar sker som avviker från byggprocessens etablerade norm skapas möjligheter för företag med passande resurser och erbjudanden. / Godkänd; 2008; 20081105 (ysko)
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CFRP Strengthening of Cut-Out Openings in Concrete Walls – Analysis and Laboratory TestsPopescu, Cosmin January 2017 (has links)
Redesigning buildings to improve their space efficiency and allow changes in use is often essential during their service lives to comply with shifts in living standards and functional demands.This may require the introduction of new openings in elements such as beams, walls, and slabs,which inevitably reduces their structural performance and hence requires repair or strengthening.However, there are uncertainties regarding both the effects of openings and the best remedial optionsfor them. Traditionally, two methods have been used to strengthen reinforced concrete (RC) walls with openings, these being either to create a frame around the opening using RC/steel membersor to increase the cross-sectional thickness. Currently, intervention in existing buildings must be minimal in order to minimise inconvenience caused by limiting the use of the structure during repairs. One option is to use externally-bonded fibre-reinforced polymers (FRPs). In this study, the author reports on an experimental investigation of the effectiveness of carbonFRP (CFRP)–based strengthening for restoring the axial capacity of a solid reinforced concretewall after cutting openings. Nine half-scale specimens, designed to represent typical wall panels in residential buildings with and without door-type openings, were tested to failure. The walls were tested in two-way action and subjected to axial loading with low eccentricity (defined as one sixth of the wall’s thickness) along the weak axis to represent imperfections due to thickness variation and misalignment of the panels during the construction process. An extensive instrumentation scheme was used to monitor the specimen’s behaviour during the loading cycles. In addition to classical approaches for measuring strains and displacements, optical 3D measurements were also acquired using the digital image correlation (DIC) technique. These provided better overviews of the failure mechanism by recording the crack pattern development and deformation of the walls throughout the loading history. Reducing the cross-sectional area by cutting out openings i.e. 25% (hereafter referred to as small opening) and 50% (hereafter referred to as large opening) led to 36% and 50% reductions in peak loads, respectively. In both situations the failure was brittle due to crushing of concrete with spalling and reinforcement buckling. The CFRP strengthening increased the axial capacity of walls with small and large openings by 34 – 50% and 13 – 27%, respectively. This partially restored theircapacities to 85 – 95% and 57 – 63% of their precutting capacity (i.e. solid wall), respectively. A procedure based on a rigid-plastic approach for evaluating the ultimate load of walls with cut-out openings that have been strengthened with FRPs was also proposed in this study. Predictions made using the proposed method agree closely with experimental results. / <p><strong>Examining Committee</strong>: Professor Karin Lundgren, Division of Structural Engineering, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden</p><p>Professor Henrik Stang, Section for Structural Engineering, Department of Civil Engineering, Technical University of Denmark, Lyngby, Denmark</p><p>Professor Mats Oldenburg, Division of Mechanics of Solid Materials, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden</p>
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