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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Fire-Robust Structural Engineering: A Framework Approach to Structural Design for Fire Conditions

Johann, Matthew A. 19 December 2002 (has links)
"Thanks to significant worldwide research directed at understanding and predicting structural behavior at elevated temperatures, analytical methods are available to support a rational, performance-based approach to the structural design of buildings for fire conditions. To utilize these analytical methods effectively, structural engineers need guidance on reliable and appropriate approaches to dealing with a variety of factors, including the effects of fire protection measures, temperature-dependent thermal and structural properties, elastic and inelastic behavior of structural components and assemblies, and thermal and structural response of framing connections. To meet the objective of guiding the structural engineer in appropriate analytical methods and parameter values for performance-based structural fire protection, this thesis proposes a comprehensive way of thinking about the design and analysis of structures for fire conditions. This integration of structural engineering and fire protection engineering into a functional framework is defined herein as Fire-Robust Structural Engineering (FRSE). The FRSE process, which is presented as a series of flowcharts, is designed to guide the structural engineer in executing the functions involved in the design of fire-safe structures and to help identify informational needs critical to these tasks. Currently, mechanisms for identifying possible resources to fulfill fire-related informational needs are generally organized for the convenience of the fire research community. Identification of resources that provide appropriate information for fire-robust structural engineering, such as laboratory fire test results, parametric studies of analytical methods, and other sources of guidance, is often difficult because these resources are rarely organized and presented for the benefit of structural engineers. To begin to resolve this problem, this thesis has developed a prototype information management system (IMS) based on the framework of the FRSE process. The IMS addresses the critical challenge of organizing and presenting the available knowledge and data in a format that is consistent with the perspective and informational needs of the structural engineer. The prototype version of the IMS has been implemented using a Microsoft Excel® platform. In addition to guidance in utilizing specific analytical methods and choosing appropriate parameter values, the structural engineer also requires an understanding of the input requirements and accuracy of various analytical methods in order to make informed decisions regarding which methods are appropriate for use with different structural configurations. Therefore, this thesis includes a model study as an example of a resource that could aid the structural engineer in making such decisions. The model study compares various analytical methods (simplified spreadsheet applications and advanced finite element techniques) to published laboratory test data and discusses concerns that the structural engineer must keep in mind when using each method. Conclusions are drawn regarding the appropriateness of each analytical method to the analysis of a fully restrained, spray-protected steel beam. Given this type of information, the structural engineer can make decisions regarding the types of analytical methods and the level of analytical sophistication required to solve a given design problem."
132

Gaisrų ekspertizių analizė ir jų plėtojimo perspektyvos / Fire investigations analysis and development

Morkūnas, Algirdas 30 January 2006 (has links)
The main purpose of the Master paper is to make fire investigations analysis, to find its problems ant find a way to solve them. Also suggest new alternative fire investigation methods. In the first part of my work I studied fire investigation analysis disputed all the methods of fire investigation used in Lithuania. I found and disputed limitations of fire investigation methods and found few solutions for them. I describe new alternative fire investigation methods used abroad. In the second part of my work I have analyzed new fire investigation method- fire dynamic simulator. I Studied principles and use opportunities of FDS- MOKEWIEV and SMARTFIRE programs. In the third part I wrote few concrete examples when these two fire dynamic simulation programs were used. I have also described test computation with SMARTFIRE fire dynamic simulator. I have wrote conclusions and suggested about fire investigation.
133

Distortional buckling behaviour of cold-formed steel compression members at elevated temperatures

Ranawaka, Thanuja January 2006 (has links)
In recent times, light gauge cold-formed steel sections have been used extensively in residential, industrial and commercial buildings as primary load bearing structural components. This is because cold-formed steel sections have a very high strength to weight ratio compared with thicker hot-rolled steel sections, and their manufacturing process is simple and cost-effective. However, these members are susceptible to various buckling modes including local and distortional buckling and their ultimate strength behaviour is governed by these buckling modes. Fire safety design of building structures has received greater attention in recent times due to continuing loss of properties and lives during fires. Hence, there is a need to fully evaluate the performance of light gauge cold-formed steel structures under fire conditions. Past fire research has focused heavily on heavier, hot-rolled steel members. The buckling behaviour of light gauge cold-formed steel members under fire conditions is not well understood. The buckling effects associated with thin steels are significant and have to be taken into account in fire safety design. Therefore, a research project based on extensive experimental and numerical studies was undertaken at the Queensland University of Technology to investigate the distortional buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. As the first phase of this research program more than 115 tensile coupon tests of light gauge cold-formed steels including two steel grades and five thicknesses were conducted at elevated temperatures. Accurate mechanical properties including the yield strength, elasticity modulus and stress-strain curves were all determined at elevated temperatures since the deterioration of the mechanical properties is one of the major parameters in the structural design under fire conditions. An appropriate stress-strain model was also developed by considering the inelastic characteristics. The results obtained from the tensile coupon tests were then used to predict the ultimate strength of cold-formed steel compression members. In the second phase of this research more than 170 laboratory experiments were undertaken to investigate the distortional buckling behaviour of light gauge coldformed steel compression members at ambient and elevated temperatures. Two types of cross sections were selected with various thicknesses (nominal thicknesses are 0.6, 0.8, and 0.95 mm) and both low and high strength steels (G250 and G550 steels with minimum yield strengths of 250 and 550 MPa). The experiments were conducted at six different temperatures in the range of 20 to 800°C. A finite element model of the tested compression members was then developed and validated with the help of experimental results. The degradation of mechanical properties with increasing temperatures was included in finite element analyses. An extensive series of parametric analyses was undertaken using the validated finite element model to investigate the effect of all the influential parameters such as section geometry, steel thickness and grade, mechanical properties and temperature. The resulting large data base of ultimate loads of compression members subject to distortional buckling was then used to review the adequacy of the current design rules at ambient temperature. The current design rules were reasonably accurate in general, but in order to improve the accuracy further, this research has developed new design equations to determine the ultimate loads of compression members at ambient temperature. The developed equation was then simply modified by including the relevant mechanical properties at elevated temperatures. It was found that this simple modification based on reduced mechanical properties gave reasonable results, but not at higher temperatures. Therefore, they were further modified to obtain a more accurate design equation at elevated temperatures. The accuracy of new design rules was then verified by comparing their predictions with the results obtained from the parametric study. This thesis presents a description of the experimental and numerical studies undertaken in this research and the results including comparison with simply modified current design rules. It describes the laboratory experiments at ambient and elevated temperatures. It also describes the finite element models of cold-formed steel compression members developed in this research that included the appropriate mechanical properties, initial geometric imperfections and residual stresses. Finally, it presents the details of the new design equations proposed for the light gauge coldformed steel compression members subjected to distortional buckling effects at elevated temperatures.
134

Behaviour and design of cold-formed steel compression members at elevated termperatures

Heva, Yasintha Bandula January 2009 (has links)
Cold-formed steel members have been widely used in residential, industrial and commercial buildings as primary load bearing structural elements and non-load bearing structural elements (partitions) due to their advantages such as higher strength to weight ratio over the other structural materials such as hot-rolled steel, timber and concrete. Cold-formed steel members are often made from thin steel sheets and hence they are more susceptible to various buckling modes. Generally short columns are susceptible to local or distortional buckling while long columns to flexural or flexural-torsional buckling. Fire safety design of building structures is an essential requirement as fire events can cause loss of property and lives. Therefore it is essential to understand the fire performance of light gauge cold-formed steel structures under fire conditions. The buckling behaviour of cold-formed steel compression members under fire conditions is not well investigated yet and hence there is a lack of knowledge on the fire performance of cold-formed steel compression members. Current cold-formed steel design standards do not provide adequate design guidelines for the fire design of cold-formed steel compression members. Therefore a research project based on extensive experimental and numerical studies was undertaken at the Queensland University of Technology to investigate the buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. As the first phase of this research, a detailed review was undertaken on the mechanical properties of light gauge cold-formed steels at elevated temperatures and the most reliable predictive models for mechanical properties and stress-strain models based on detailed experimental investigations were identified. Their accuracy was verified experimentally by carrying out a series of tensile coupon tests at ambient and elevated temperatures. As the second phase of this research, local buckling behaviour was investigated based on the experimental and numerical investigations at ambient and elevated temperatures. First a series of 91 local buckling tests was carried out at ambient and elevated temperatures on lipped and unlipped channels made of G250-0.95, G550-0.95, G250-1.95 and G450-1.90 cold-formed steels. Suitable finite element models were then developed to simulate the experimental conditions. These models were converted to ideal finite element models to undertake detailed parametric study. Finally all the ultimate load capacity results for local buckling were compared with the available design methods based on AS/NZS 4600, BS 5950 Part 5, Eurocode 3 Part 1.2 and the direct strength method (DSM), and suitable recommendations were made for the fire design of cold-formed steel compression members subject to local buckling. As the third phase of this research, flexural-torsional buckling behaviour was investigated experimentally and numerically. Two series of 39 flexural-torsional buckling tests were undertaken at ambient and elevated temperatures. The first series consisted 2800 mm long columns of G550-0.95, G250-1.95 and G450-1.90 cold-formed steel lipped channel columns while the second series contained 1800 mm long lipped channel columns of the same steel thickness and strength grades. All the experimental tests were simulated using a suitable finite element model, and the same model was used in a detailed parametric study following validation. Based on the comparison of results from the experimental and parametric studies with the available design methods, suitable design recommendations were made. This thesis presents a detailed description of the experimental and numerical studies undertaken on the mechanical properties and the local and flexural-torsional bucking behaviour of cold-formed steel compression member at ambient and elevated temperatures. It also describes the currently available ambient temperature design methods and their accuracy when used for fire design with appropriately reduced mechanical properties at elevated temperatures. Available fire design methods are also included and their accuracy in predicting the ultimate load capacity at elevated temperatures was investigated. This research has shown that the current ambient temperature design methods are capable of predicting the local and flexural-torsional buckling capacities of cold-formed steel compression members at elevated temperatures with the use of reduced mechanical properties. However, the elevated temperature design method in Eurocode 3 Part 1.2 is overly conservative and hence unsuitable, particularly in the case of flexural-torsional buckling at elevated temperatures.
135

Lös inredning fri från flamskyddsmedel : En studie kring naturligt flamskyddat materials flamhärdighettillsammans med ull i en vävd konstruktion

Svensson, Josefine January 2018 (has links)
Flamskyddsmedel har visat sig ha en stor påverkan på både miljö och hälsa. Den grupp flamskyddsmedel som i stor utsträckning har använts sedan slutet på 70-talet till början av 00-talet för textilier är polybromerade difenyletrar (PBDE). De är halogenerade ämnen som är svårnedbrytbara, persistenta, i vissa fall även bioackumulerande och toxcistiska. Studier har visat att dessa ämnen upptäckts i både miljö och i människokroppen. Människan exponeras av dessa ämnen, framförallt genom damm och livsmedel. I synnerhet feta fiskar eftersom PBDE drar sig till organismer och fettvävnader. I takt med att brandkraven i många länder ökar är behovet av ett substitut för bromerade flamskyddsmedel stort. Flera typer av PBDE är idag förbjudna i Europa men problemet kvarstår då det fortfarande existerar i importerade produkter. För att komma ifrån flamskyddsmedel i lös inredning, exempelvis soffor och madrasser skulle ett barriärmaterial innehållande naturligt flamskyddade material vara ett bra substitut.   För lös inredning är det viktigt med komfort, det fanns i studien ett intresse av att se hur naturligt flamskyddat material tillsammans med ull betedde sig vid en flamspridning. Ull i sig har en hög komfort och har ett naturligt flamskydd på grund av sitt höga LOI. För att uppnå ett resultat på vilken FR-fiber som skulle studeras vidare tillsammans med ull, har flamtester på Kevlar, Nomex, Protex och Flamestop utförts. De är uppbyggda med olika typer av naturligt flamskydd i form av aramider, modakryl och fosfor behandlad viskos.   Med resultatet från flamtesterna utfördes vidare tester och analyser på tre kombinationer av Flamestop/Ull, innehållande tre olika procentsatser. Testmetoder i form av antändning och flamspridning har utförts på de olika kombinationerna, för att göra det möjligt att analysera om hur de flamskyddade materialet uppförde sig tillsammans med ull. Samt om det gjorde någon skillnad vilken procentandel Flamestop kombinationen innehöll.   Resultatet av testmetod för antändning på tre spridda procentandelar Flamestop/Ull som erhölls, var att en högre procentandel Flamestop gentemot ull gjorde det möjligt för materialet av självslockna i ett tidigt stadie. I flamspridningstestet visade det sig att procentandelarna inte gjorde någon skillnad för spridningens framfart. Det gick att utläsa av testerna att proverna med flamskydd i vinkelrät riktning mot flammans riktning bildade ett skyddande skikt av förkolnad fosfor från Flamestop. Flamman och Flamestop i längsgående riktning resulterade i större skada på materialet. För att göra det möjligt att undersöka mer om riktningen på det flamskyddade materialet hade det varit intressant att studera flamspridningen med materialet i både väft och varp. / Flame-retardants have a great impact on the environment and health. Polybrominated diphenyl ethers (PBDE) are the group of flame-retardants that mainly has been used since its entrance in the late 70s until the early 00s. PBDEs consist of Organobromine compounds, different types of halogenated compounds, which are highly resistant to degradation, persistent and in some cases even bioaccumulative and toxic. It has been ensured in previously studies that PBDEs has been found in the human body and in the environment. Humans are exposed every day to these pollutants through dust, food and especially from fatty fishes, as living organisms and fatty tissues are easily attracted to PBDE. A lot of the existing PBDE are forbidden in Europe; however, the issue still exist as imported products can contain PBDE. As the fire safety regulations in many countries increases, it is necessary to find a substitute for flame-retardants. To lessen or completely remove flame-retardants in loose interiors, as couches and mattresses a barrier-material could be a good substitute.   Comfort is an important component for loose interiors; in this study there was an interest to see how a material with inherent natural flame resistance behaved with wool. Wool, that has a good comfort and a natural resistance of flame, due to its high LOI. To decide which FR-fibre that will be looked into and analysed in this essay an ignition test on Kevlar, Nomex, Protex and Flamestop were made. These materials have different structures of flame resistance, in form of aramids, modacrylic and phosphorus viscose.   Three different percentages of Flamestop/Wool were created from the results of the previous mentioned ignition test. These three percentages were weaved into a plain weave, tested and analysed. Ignition and flame spread were tested on the weaves, analysed to see how the natural flame resistant material behaved together with wool and if there were any differences when comparing the different test specimens.   The result of the ignition and flame spread tests showed that the percentages of Flamestop played a role in the ignition test; the ability to extinguish was greater with a higher percentage of Flamestop in the weave. It was not possible to see a difference in the test of flame spreading. The test specimens with the FR-fibre perpendicular to the flames direction showed a better result than the test specimens with the FR-fibre in a longitudinal direction to the flame. It would be of interest to study weaves with FR-fibres in both directions of warp and weft.
136

Análise numérica e experimental de vigas de madeira laminada colada em situação de incêndio / Numerical and experimental analysis of glued laminated timber in fire situation

Gisele Cristina Antunes Martins 29 July 2016 (has links)
Elementos estruturais de Madeira Laminada Colada (MLC) têm sido muito utilizados na América do Norte e na Europa. Entretanto no Brasil há restrições quanto ao uso, principalmente, em razão da insegurança diante de potenciais riscos relacionados a incêndios. Este trabalho investigou o comportamento térmico e mecânico de elementos estruturais de MLC expostos à curva de incêndio-padrão ISO 834, preparados com duas espécies de madeira (Eucalyptus e Pinus) sem adição de tratamentos preservantes. Adicionalmente, elementos tratados com preservante ignífugo a base Borato de Cobre Cromatado (MOQ® OX 50CCBO) ou tratamento retardantes ao fogo (OSMOGUARD® FR100) também foram utilizados para analisar a influência na carbonização. O objetivo principal da pesquisa foi analisar a resistência ao fogo de elementos de MLC, avaliando a influência da espécie de madeira, a influência da densidade, bem como os efeitos dos tratamentos preservantes. O programa experimental foi realizado no forno horizontal a gás instalado no Departamento de Engenhara das Estruturas - EESC/USP, com dimensões internas de 3m x 4m x 1,5m, e as análises numéricas foram implementadas no pacote computacional ABAQUS. O modelo numérico, com vistas ao monitoramento a deflexão no meio do vão e a avaliação da distribuição da temperatura ao longo da profundidade dos elementos, foram desenvolvidos e os resultados obtidos foram comparados com os dados obtidos por meio das análises experimentais. Métodos de cálculo propostos por diferentes autores e regulamentações internacionais foram aplicados para verificação das propostas de dimensionamento em situação de incêndio. A comparação dos resultados mostrou que a utilização dos métodos de dimensionamento (simplificado ou avançado) representa risco à segurança contra incêndio caso utilize valores para a taxa de carbonização das espécies nacionais determinados a partir dos métodos de cálculo ou normas internacionais. / Structural elements of Glued Laminated Timber (glulam) have long been used in North America and Europe, but their use is still restricted in Brazil for safety reasons, especially related to potential risks in face of fire. The present work investigated the thermal and mechanical behavior of structural elements of glulam exposed to fire standard ISO 834. The glued laminated timber was produced from two wood species (Eucalyptus and Pinus) without any treatments. However, elements treated with wood treatments like Copper Chrome Boron (MOQ® OX 50 -CCB-O) or fire retardant treatment (OSMOGUARD® FR100) were also used to investigate their influence on charring. The main objective of this study was to assess the fire resistance of the glulam elements, evaluating the influence of wood species and, consequently, the influence of density, as well as the effects of preservative treatment. The experimental program was carried out in a gas oven, with internal dimensions of 3m x 4m x 1.5m, and the numerical analyses were performed by ABAQUS. The numerical analyses aimed to monitor the deflection in the middle of the span as well as the temperature distribution along the depth of the elements. The results obtained from both the experimental and numerical analyses were compared. Calculation methods proposed by different authors and international regulations have been applied for verification of the proposed design in fire. A comparison of the results show that the use of calculation methods (simplified and advanced) represents a risk to fire safety in case of using the values of char rate for Brazilian wood species determined from the calculation methods.
137

Extreme PIV Applications: Simultaneous and Instantaneous Velocity and Concentration Measurements on Model and Real Scale Car Park Fire Scenarios

Horvath, Istva'n 10 October 2012 (has links)
This study is a presentation of an instantaneous and simultaneous velocity and concentration measurement technique and its applications on car park fire scenarios. <p>In this actual chapter 1 general introduction is given to each chapter. Chapter 2 is dedicated to a detailed description of the instantaneous and simultaneous velocity and concentration measurement technique and its associated error assessment methodology. The name of the new technique is derived from the names of the acquired parameters (VELocity and COncentration) and shall be hereafter referred to as VELCO. After having validated and performed an error assessment of this technique, it is applied to an investigation of full-scale car park (30 m x 30 m x 2.6 m – Gent / WFRGENT) fire cases in chapter 3. The measurements were carried out with the financial support of IWT-SBO program. In the full-scale measurements only the velocity part is applied of VELCO, yet it can be considered as its application since the special data treating was developed and implemented in the Rabon (see: §2.1.2) program, which is the software of the new technique along with Tucsok (see: §2.1.1) and they will be both discussed in the related chapter. Here it is enough to mention that the concentration and velocity information can be obtained independently as well. During the full-scale measurements, beyond of VELCO the smoke back-layering distances (SBL) are also derived from the temperature values, which were measured by thermocouples under the ceiling in the midline of the car park. The critical velocity, which is an important measure of fire safety, can be obtained from the SBL results. In chapter 4, isothermal fire modeling is surveyed in order to present how full-scale fires are modeled in small-scale. In this part of the study the theory of fire related formulae and an isothermal model are described. Here it is important to stress the fact that the fire modeling is not directly related to the VELCO technique. However it connects the full-scale to the small-scale measurements, which the technique is applied on. Chapter 5 discusses small-scale measurements (1:25 – Rhode Saint Genese / VKI) on the car park introduced in chapter 3 and their validation. After the validation, more complex car parks scenarios are also investigated due to the easy to change layout in the small-scale model with respect to the full-scale car park. In this chapter the smoke back-layering distances are obtained by VELCO. Finally, in chapter 6 important conclusions are drawn with the objective of increasing fire safety. <p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished
138

Studium chování izolačních materiálů na bázi organických vláken po zabudování do konstrukce / Possibilities of improvement of fire properties of insulation materials based on organic fibers

Urbánek, Tomáš January 2019 (has links)
This work is focuses on the modification of organic fiber insulating materials in terms of their reaction to fire after installation into the construction. The target is to find a way to improve the reaction to fire and to at least reach the reaction to fire D.
139

Novostavba polyfunkčního domu v Uherském Hradišti / Mixed-use Building in Uherské Hradiště

Blaha, Michael January 2020 (has links)
The diploma thesis deals with the project documentation of the multifunctional house in Uherské Hradiště on plot no. 712/7 in the cadastral area of Uherské Hradiště. The building has two floors and a basement. On the ground floor there is a commercial area and a café. Office space is designed on the second floor. The building is designed as a skeleton with filling masonry, with a flat roof and is insulated with ETICS contact insulation system.
140

Domov pro seniory v Telnici / Pension for the Elderly in Telnice

Konečná, Petra January 2013 (has links)
Topic of this master’s thesis is a retirement house in village Telnice. The project was designed directly for village Telnice according to their requirements. It is a three-floor construction complied with country style. The building has a saddle roof. A flat roof is used over terraces which join each floor with the outside. Construction material is brick masonry with a thermal insulation system. Parts of the diploma’s thesis are also calculations of the thermal-technical parameters and fire safety of the building, concrete structures and technical equipments of building.

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