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

Design fires in underground hard rock mines

Hansen, Rickard January 2011 (has links)
During several decades considerable research activities have been conducted with respect to fires in coal mines, but the research activities with respect to hard rock mines have been limited. As the hard rock mines are getting more complex the need for deeper understanding of fires in underground hard rock mines are getting more in demand. The more urgent demands are the need for more specific heat release rate curves as design fires, applicable fire experiments and any method that would allow for the calculation of the total heat release rate curve of an object. This thesis presents a number of examples on design fire curves applicable to underground hard rock mines; it also presents the results of model scale fire experiments and methods for calculating the total heat release rate of several objects at uniform as well as non-uniform conditions. Tests were carried out in a model scale tunnel using wooden pallets as fire load. The parameters tested were the distance between piles of pallets and longitudinal ventilation rate. It was found that an increasing ventilation rate also increases the peak heat release rate. When studying the curves of heat release rates it was found that when the distance between the ignited pile and the second pile increased to a certain level the delayed ignition of the second pile will result in that the peak heat release rate of the adjacent piles will not occur simultaneously. The ignition data indicated that the ignition time of adjacent piles decreased as the longitudinal ventilation increased.  A method using a critical heat flux as ignition criterion exhibited very good agreement with the corresponding experiments for both uniform as well as non-uniform conditions. The methods using the ignition temperature as ignition criterion did not agree very well with any of the corresponding experiments. / GRUVAN
2

Characterising a Design Fire for a Deliberately Lit Fire Scenario

Richards, Paul Leonard Edward January 2008 (has links)
Deliberately lit fires make up over 15% of all fires in New Zealand buildings yet they are typically omitted from the design brief for fire engineering purposes. This report examines where deliberately lit fires should be included as part of the fire engineering design by examination of all deliberately lit fires recorded in the New Zealand Fire Incident Reporting System (NZ FIRS) between the years 1996 and 2006. The main types of buildings identified where consideration of deliberately lit fires within the design would provide benefits are: · Prisons · Psychiatric institutions · Schools · Crowd activities · Attached accommodation The report also examined what is required to include deliberately lit fires as part of the design process. Based on an analysis of the fire incident statistics, the majority of deliberately lit fires are the result of unplanned activities and existing design fires will be adequate. Two critical fire scenarios were identified as exceeding these requirements, the ignition of multiple fires and the use of accelerants. Greater life safety benefits are obtained by considering accelerants. In the case of multiple fires, each fire is likely to be within the capabilities of a fire engineered building however a number of such fires may overwhelm the fire protection features of a building. A number of issues for the fire engineer to consider are briefly discussed. In the case of accelerants, a number of experiments were completed to characterise the heat release rate and species production of a Molotov cocktail based on the fuel volume used. A second round of experiments extended this work by examining the scenario where a Molotov cocktail containing 1000 milliliters of petrol was deployed within a stairwell.
3

Comparisons of Structural Designs in Fire

Collette, Kristin A 03 May 2007 (has links)
How well do calculations methods prescribed in today's design codes and standards represent conditions in natural fires? Can the temperature and behavior of a steel member in fire be predicted from these calculations? A literature review of structural fire codes, full scale fire tests, published fire test data, the function and selection of design fires, mechanical and thermal behaviors of structural steel, and numerical calculation methods for the temperature of steel members was conducted as a foundation to analyze whether a not a structural fire engineer can answer these questions. Through comparisons of published data from four natural fires tests performed at the Cardington test facility in the United Kingdom to numerical calculations based upon prescribed methods from Eurocode 3 and the Swedish Design Manual, time-temperature curves were developed to demonstrate the variation in temperature of the recorded data in the natural fire tests at Cardington to the equivalent members being analyzed with numerical calculation methods. When available, fire compartment characteristics were replicated during numerical calculations to ensure the highest correlation between the recorded and calculated results. An Excel tool was created to rapidly calculate and produce the resulting time-temperature curves as well as yield strength, modulus of elasticity, and load carrying capacity using a variety of input parameters including design fire data and steel member selection. The goal of the Cardington fires study was to provide comparisons of published natural fire data to results of numerical calculation methods from the codes. Additional comparisons were developed using a US Office design to show the effects of changing compartment and design parameters on the steel temperature, yield strength, elastic modulus and load carrying capacity. Differences found in temperature of steel members between the published Cardington data and numerical calculations proved the difficulty of predicting the behavior of a structural steel beam throughout an entire length of a fire or even until failure. Discussion of results addressed the selection of design fires, input parameters, structural layouts of office buildings, heating and cooling phases of steel members, and failure criteria.
4

Design hasičského zásahového vozidla / Design of fire fighting and rescue vehicle

Metlický, Martin January 2014 (has links)
The topic of this master’s thesis is design of fire fighting and rescue vehicle, more specifically wildland fire apparatus primarily intended for difficult terrain. The main aim of this design is to create functional object fulfilling ergonomic, technical, and aesthetic demands.
5

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.

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