• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 104
  • 24
  • 17
  • 9
  • 8
  • 4
  • 4
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 243
  • 243
  • 68
  • 67
  • 34
  • 33
  • 32
  • 28
  • 25
  • 25
  • 20
  • 20
  • 20
  • 19
  • 19
  • 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.
41

A Comparison between two different Methods to Verify Fire Safety Design in Buildings

Ronstad, David January 2017 (has links)
In today’s Nordic construction industry, it is difficult for new and innovative building solutions to be introduced due to prescriptive and inflexible regulations. Trading products and services cross-border is something that could loosen the tough market, but this is not possible due to the lack of common international frameworks that is performance based with the possibility to perform fire safety engineering. This is something that the Nordic Innovation project group called Fire Safety Engineering for Innovative and Sustainable Building Solutions wants to change. By introducing a new probabilistic method to verify fire safety in buildings, with the intention to become a Nordic standard, so will hopefully parts of these problems be resolved. The fourth work package of the project includes field testing of the new method which this thesis is a part of. The idea is to asses and improve the new probabilistic approach by comparing it to an existing non-probabilistic method and introduce ameliorating recommendations. Comparison of the probabilistic method is performed against a Swedish verification process that’s based on the General recommendations on analytical design of fire safety strategy (BBRAD) by verifying fire safety in a car park, that is located below an office building, with both verification methods. The two performance-based analyses treat deviations from a prescriptive solution, performed with the Boverket’s Building Regulations (BBR), and the results of these verifications is compared. The requirements that is verified are; escape in event of fire, protection against the outbreak of fire, protection against the development and spread of fire and smoke in buildings, protection against spread of fire between buildings, possibility of rescue responses and ensuring fire resistance in the structural members. Fire safety designs and approaches for treatment of the deviations are compared and analysed which concludes in the improvement recommendation that’s been presented.  Questions that has been answered during the work process is: How do the methods treat the possibility of a fire safety design without sprinkler? What is the main difference between the two verification methods? Which improvements could be done to the new Probabilistic method?  The recommendations of improvement that has been presented is based on the work process of the probabilistic approach and the comparison with the Swedish verification process. Development of the following areas is advocated: Treatment of critical levels for evacuation scenarios  Form a common Nordic statistical database Improved guidance of how to complete the validation analysis The thesis does not include all parts that’s required in a fire safety design but will merely focus on the deviations of the pre-accepted solution. The verification is only performed on the car park, i.e. the office part of the building is not included. / I dagens nordiska byggbransch är det svårt för nya och innovativa byggnadslösningar att införas på grund av de preskriptiva och fyrkantiga regelverk som finns. Handel av produkter och tjänster över gränserna är något som kan luckra upp den tuffa marknaden, men det är svårt på grund av bristen utav gemensamma internationella regelverk som är funktionsbaserade med möjlighet till fire safety engeinnering. Det är något som ett nordiskt innovationsprojekt kallat Fire Safety Engineering for Innovative and Sustainable Building Solutions vill förändra. Genom att införa en ny probabilistisk metod för att verifiera brandsäkerheten i byggnader, med avsikten att skapa en nordisk standard, kan förhoppningsvis delar av dessa problem lösas. Det fjärde arbetspaketet inom projektet består av att testa den nya metoden, vilket denna avhandling är en del av. Tanken är att bedöma och ta fram förbättringsförslag till den nya probabilistiska metoden genom att jämföra den med en befintlig scenariobaserad metod och presentera förbättringsrekommendationer. Jämförelse av probabilistiska metoden utförs mot en svensk verifieringsprocess som baseras på Boverkets allmänna råd om analytisk dimensionering av byggnaders brandskydd (BBRAD) genom att verifiera brandsäkerheten i ett parkeringsgarage, som ligger under en kontorsbyggnad, med båda verifieringsmetoderna. De två funktionsbaserade analyserna behandlar avvikelser från en förenklad dimensionering, som är utförd enligt Boverkets Byggregler (BBR), och resultaten av dessa verifikationer jämförs. De krav som verifieras är; utrymning i händelse av brand, skydd mot uppkomst av brand, skydd mot utveckling och spridning av brand och rök i byggnader, skydd mot brandspridning mellan byggnader, möjlighet till räddningsinsats och att säkerställa bärförmåga vid brand. Brandskyddets utformning och metodernas behandling av avvikelserna jämförs och analyseras vilket konkluderar i de rekommendationer för förbättring som presenteras. Frågor som har besvarats under arbetsprocessen är: Hur behandlar metoderna möjligheten att dimensionera brandsäkerheten utan sprinklersystem? Vad är den stora skillnaden mellan de två verifieringsmetoderna? Vilka förbättringar kan göras på den nya probabilistiska metoden? Rekommendationerna till förbättring som har tagits fram är baserad på arbetsprocessen i den probabilistiska metoden och jämförelsen med den svenska verifieringsprocessen. Utveckling av följande områden förespråkas: Behandling av kritiska nivåer i utrymningsscenarion Uppställning av en gemensam statistiskdatabas för de nordiska länderna Förbättrad förklaring om hur man utför valideringarna av analysen Avhandlingen omfattar inte alla delar som behövs vid bandskyddsprojektering utan fokusera endast på avvikelserna från den förenklade dimensioneringen. Verifikationen är endast utförd på parkeringsgaraget, det vill säga kontorsdelen av byggnaden behandlas inte. / Fire Safety Engineering for Innovative and Sustainable Building Solutions
42

Comparing a full scale test with FDS, FireFOAM, McCaffrey & Eurocode

Edin, Erik, Ström, Mattias January 2019 (has links)
In the rapidly growing field of CFD-calculations (Computational Fluid Dynamics), companies and organizations are bringing forth new tools, tools that display an image of a given fire scenario. These tools are developed because they provide time efficiency as well as a sustainable economic approach. Another useful tool is analytical solutions, these analytical solutions serve the same purpose as CFD-modeling, providing results of a given scenario. The purpose of this thesis was to simulate a fire plume with two different CFDprograms and compare the gas temperature from each simulation with a full-scale test. Also, analytical solutions were used to perform the same comparisons. Four different calculation models were utilized to obtain results. The CFD-programs were FDS (Fire Dynamics Simulator) and FireFOAM. The analytical solutions were performed using McCaffrey´s plume equation and Eurocode solutions for localized fire temperatures. FDS is a very well documented program, due to this, problems that arose were easily fixed. The structure of FDS enables the user to maneuver the program easily. SmokeView was used to visualize the simulation. FireFOAM is written in C++ and is operated through the command prompt. The structure of the program was time-consuming to understand mainly because of two reasons, primarily because the authors lack of knowledge in coding in C++, and second because of the LINUX environment. Moreover, the process of working in FireFOAM was mostly through trial and error. On some occasions, issues arose that could be solved by communication with other CFD users at CFD-Online. When major problems occurred, regarding the code or other CFD issues, Johan Anderson at RISE Research Institutes of Sweden guided us through most of these problems and enabled us to move forward with the work. ParaView was used to visualize the simulation, and Excel was used to evaluate the temperature data from the FDS- and FireFOAM simulations. For the calculations in FDS and FireFOAM, a sensitivity analysis was performed to see which grid size presented best results in each program. A grid size of 5 cm, 10 cm, and 20 cm were applied in FDS, and in FireFOAM the grid dimensions were set to 5 cm and 10 cm. The results showed that 5 cm was the most appropriate grid size for both programs. It would have been more favorably to simulate with several different grid sizes, to further strengthen the grid analysis. Though, due to the time frame of the thesis, further simulations were not performed. Calculations were repeated for the same scenario only with a lower HRR (Heat release rate). An extensive sensitivity analysis was conducted for FDS in the form of two different simulations. One simulation where HRR was the same as the full-scale test but with twice the area of the burner. In the second simulation, the same area was used on the burner as the fullscale test, but with half the HRR. Results from the analytical solutions were easy to achieve; however, the model has some limitations regarding calculations within the flame region. The estimated gas temperature, using FDS, aligns well with the full-scale test. The temperatures analyzed from FireFOAM deviated in general through the flame region and reached unreasonable high temperatures close to the ceiling. Since the analytical solutions were based on different conditions compared to those applied in the full-scale test, it was expected that the results should deviate. However, McCaffrey plume equations can still be used to give an approximate picture of scenarios similar to that of the full-scale test, and the same applies to Eurocode solutions for localized fire temperatures. Analysis of the results shows that FDS can be used to simulate similar scenarios. FireFOAM simulates a gas temperature that is overestimated within the flame region. One of the reasons for this was due to the grid size since the sensitivity analysis III showed that a refined grid size resulted in more correct temperature value, the reason for not simulating with a more refined grid size was due to the restricted time frame of this thesis. FireFOAM is, at present, recommended for researchers who wish to use the code for specific purposes. Therefore, given the same premises, FireFOAM is not recommended for the standard fire safety analysis.
43

Performance Based Design of Structural Steel for Fire Conditions

Parkinson, David L 21 August 2002 (has links)
"As jurisdictions throughout the world progress toward performance based building codes, it is important that the proper tools be made available to the engineering profession in order that they may take full advantage of these new codes. There is currently a large body of work written on the subject of performance based or engineered structural fire safety. Unfortunately, most of this information is scattered throughout technical journals from different countries and organizations, and not easily accessible to the practicing engineer. Under the current prescriptive code regime there is generally no requirement to undertake an engineering approach to structural fire safety, since the required fire resistance ratings are prescribed and the fire resistance ratings of materials/assemblies are determined through standard tests. However, these methods have been shown to be both unnecessary and expensive in some cases. A method will be developed that can be used to determine required fire resistance ratings for fire exposed structural steel based on a realistic engineering approach. A procedure is summarized for calculating time-temperature curves from a real fire in a typical compartment. With this time-temperature relationship a realistic time to failure for structural steel members can be determined. The method is summarized. Comments regarding important considerations and a worked example are provided to demonstrate the utility of the method."
44

A Conceptual Framework for Assessing Post-Earthquake Fire Performance of Buildings

Kim, Jin Kyung 25 April 2014 (has links)
Earthquakes can severely damage building structural and nonstructural systems and components, including active and passive fire protection and egress systems. If the occurrence of such damage is not anticipated at the design stage, the impact of a post-earthquake fire could be significant, as building and fire protection systems may not perform as expected. Unfortunately, even though both the seismic and fire engineering communities utilize performance-based approaches for designing well-performing and resilient buildings under earthquake and fire hazards respectively, each discipline carries out their associated building performance analyses independently. As a result, fire protection engineers have little guidance as to how to estimate structural and nonstructural building systems and component damage as inputs to help them develop post-earthquake building fire scenarios. To help bridge this gap, a conceptual framework is developed that illustrates how performance-based approaches for earthquake and fire engineering analysis and design can become more integrated for the development of post-earthquake fire scenarios. Using a fictional building in an earthquake prone area as an example, the conceptual framework is implemented to show (a) how earthquake-induced damage to building fire protection systems could be estimated using an earthquake performance assessment tool, (b) how the damage estimates might be translated into physical damage parameters in a way that is meaningful for developing post-earthquake building fire scenarios, (c) how the damage states might be implemented in terms of fire and egress modeling input parameters, and (d) how this information could be used to and compare post-earthquake building fire safety performance to a normal(undamaged) building fire conditions.
45

Development of a Performance-Based Procedure to Predict Liquefaction-Induced Free-Field Settlements for the Cone Penetration Test

Hatch, Mikayla Son 01 June 2017 (has links)
Liquefaction-induced settlements can cause a large economic toll on a region, from severe infrastructural damage, after an earthquake occurs. The ability to predict, and design for, these settlements is crucial to prevent extensive damage. However, the inherent uncertainty involved in predicting seismic events and hazards makes calculating accurate settlement estimations difficult. Currently there are several seismic hazard analysis methods, however, the performance-based earthquake engineering (PBEE) method is becoming the most promising. The PBEE framework was presented by the Pacific Earthquake Engineering Research (PEER) Center. The PEER PBEE framework is a more comprehensive seismic analysis than any past seismic hazard analysis methods because it thoroughly incorporates probability theory into all aspects of post-liquefaction settlement estimation. One settlement estimation method, used with two liquefaction triggering methods, is incorporated into the PEER framework to create a new PBEE (i.e., fully-probabilistic) post-liquefaction estimation procedure for the cone penetration test (CPT). A seismic hazard analysis tool, called CPTLiquefY, was created for this study to perform the probabilistic calculations mentioned above. Liquefaction-induced settlement predictions are computed for current design methods and the created fully-probabilistic procedure for 20 CPT files at 10 cities of varying levels of seismicity. A comparison of these results indicate that conventional design methods are adequate for areas of low seismicity and low seismic events, but may significantly under-predict seismic hazard for areas and earthquake events of mid to high seismicity.
46

Development of a Performance-Based Procedure for Assessment of Liquefaction-Induced Free-Field Settlements

Peterson, Brian David 01 December 2016 (has links)
Liquefaction-induced settlement can cause significant damage to structures and infrastructure in the wake of a seismic event. Predicting settlement is an essential component of a comprehensive seismic design. The inherent uncertainty associated with seismic events makes the accurate prediction of settlement difficult. While several methods of assessing seismic hazards exist, perhaps the most promising is performance-based earthquake engineering, a framework presented by the Pacific Earthquake Engineering Research (PEER) Center. The PEER framework incorporates probability theory to generate a comprehensive seismic hazard analysis. Two settlement estimation methods are incorporated into the PEER framework to create a fully probabilistic settlement estimation procedure. A seismic hazard analysis tool known as PBLiquefY was updated to include the fully probabilistic method described above. The goal of the additions to PBLiquefY is to facilitate the development of a simplified performance-based procedure for the prediction of liquefaction-induced free-field settlements. Settlement estimations are computed using conventional deterministic methods and the fully probabilistic procedure for five theoretical soil profiles in 10 cities of varying seismicity levels. A comparison of these results suggests that deterministic methods are adequate when considering events of low seismicity but may result in a considerable under-estimation of seismic hazard when considering events of mid to high seismicity.
47

IS IT WORKING? NARRATIVE PERSPECTIVES ON PERFORMANCE-BASED FUNDING POLICIES IN PUBLIC HIGHER EDUCATION

Unknown Date (has links)
Public higher education increasingly relies on performance-based funding (PBF) policies to enhance accountability. These policies attempt to steer institutions towards successful outcomes via performance indicators, such as graduation rates. Nationally, PBF policies continue to grow in popularity despite limited evidence that they are effective (Hillman, Tandberg, and Gross, 2014). Motivated by the apparent conflict between the widespread adoption of PBF policies and the lack of evidence that they actually improve outcomes in higher education, this dissertation investigates the perceived impacts of PBF policies. Florida’s public university system serves as the setting for the study due to its uniquely punitive PBF policy design and the model’s non-standardized performance indicators. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection
48

The International Development of Performance-Based Building Codes and Their Impact on the Australian Construction Industry in Offshore Trade

Mieldazys, Judita. A., Judita.mieldazys@dpcd.vic.gov.au January 2005 (has links)
The interplay of forces behind globalisation, promoting trade and prosperity, and the desire for offshore trade are not fully understood. This is further complicated by the role of the political economy, global sovereignty versus national boundaries, economic status of a country and community needs. The literature found that 'one size does not fit all'. Globalisation results in the consideration of global similarities such as standards, harmonisation of laws, international codes and the growth of international organisations. In addition, there is international pressure to adopt 'performance-based' designs by members of the World Trade Organization countries in order to promote trade. This research examines the development of performance-based building codes at the international level, its benefits and issues and whether it will achieve a positive impact on trade for the Australian construction industry.
49

Towards a Universal and Integrated Digital Representation of Physical Processes

Schwede, Dirk Alexander January 2006 (has links)
Doctor of Philosophy(PhD) / This thesis describes the exploration and the development of computational means to investigate the behaviour of design objects before they are available for investigation in the physical world. The motivation is to inform the design process about the design object’s performance in order to achieve better – more performance-oriented – design outcomes in the sense of energy efficiency and comfort performance than can be achieved by conventional design techniques. The research is structured into five successive parts. - Concept Development – A review of the objective domains comfort assessment and energy efficiency assessment is conducted and the design process, human design activity and the application of simulation in the architectural domain is discussed in order to identify requirements for the development of computational means for design analysis. Requirements regarding model content, model features and model integration are developed. The main requirements are that a highly integrated, three-dimensional and dynamic representation of physical processes is needed and that a universal and integrated representation is required. - Concept Formulation – Based on the identified requirements, the concept for a model is formulated. In order to achieve a universal and integrated representation of physical processes the concept uses the approach of a constructive language. Space is represented with autonomous spatial elements, called congeneric cells. Interaction between the cells is represented by near- and remote-conjunctions. Physical and geometric self-contained formulations of the model reduce the model input requirements, so that geometric information and simple property specification (material, activity) is sufficient to describe the design object in the model. - Model Development – The concept is formulated in mathematical physical terms based on well known physical laws and building physical models (first-principle approach). Heat and moisture conduction, diffusion of various components and a flow model is formulated as near-conjunction processes. Heat radiation, light and sound are modelled with a radiosity approach as remote-conjunctions. The simulation algorithm, which governs the interaction between the cells in order to represent the behaviour of space, is explained. - Computational Implementation – The concept and the model is tested by implementation of a prototype using C++ and OpenGL on a conventional Pentium 4 notebook. The prototype consists of three parts: user-interface, model translator and simulation engine. The user interface functions as model-input and result-output device. The implementation of the concept and of further model parts is described in detail. - Assessment and Testing – The developed concept and the model, as implemented in the prototype, are tested and assessed against the initially developed requirements. The physical model is assessed in regard to plausibility and accuracy of the representation of the physical phenomena. At the end of the thesis the project is summarized, the achievements of the project’s objectives are discussed critically and issues for future research are suggested. Possible applications of the developed model are listed, and the contributions to the application of computational simulation in the architectural domain, developed in this research, are named. At the current stage the required processing time and high memory requirements prevent implementation of a design assessment system, following the suggested concept, at a useful scale. Also the developed physical models require further refinement and testing. Although the general feasibility of the concept and the model was successfully demonstrated, its implementation in a fully applicable design assessment system based on the universal and integrated representation of physical processes was not achieved at this stage. While detailed description and analysis is given in the body of the thesis, detailed formulations of the work and the developed model are given in the appendix. The body and the appendix together provide a complete picture of the research presented.
50

Betydelsen av prestationsbaserad självkänsla för utbränning bland prestationssträvande högpresterare

Andersson, Åsa January 2008 (has links)
<p>Utbränning är ett högaktuellt ämne i dagens samhälle där fokus ligger på individens prestationer. Denna studies syfte var att undersöka om högpresterande individer bygger sin självkänsla på prestationer och om detta i sin tur har betydelse för utbränning. Ytterligare syfte var att undersöka om utbränning bland högpresterare med prestationsbaserad självkänsla var lika utbrett bland båda könen. I undersökningen deltog 66 tjänstemän från ett tillverkningsföretag i Mellansverige. En enkät sammanställdes av de tre befintliga och utprövade skalorna; Karolinskas utbrändhetsformulär, The Performance Based Self-esteem Scale samt en del av The Jenkins Activity Survey. Resultaten visade att prestationsbaserad självkänsla predicerade högpresterare samt att högpresterare predicerade utbränning. Även att vara kvinna predicerade utbränning. Detta visar vikten av att ta hänsyn till personalens individuella skillnader.</p>

Page generated in 0.0589 seconds