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Charring Rates for Different Cross Sections of Laminated Veneer Lumber (LVL)Tsai, Wei-heng January 2010 (has links)
Current research at the University of Canterbury is investigating the performance of a new type of timber floor system made of a timber-concrete composite. This newly proposed timber floor system uses double LVL members connected together with screwed connections to form one larger LVL member. Recent large scale fire tests showed that the joint between these two screwed LVL members opened up during fire exposure. This opening phenomenon causes concerns as the overall charring rate of the joint LVL members is subsequently increased.
The main focus of this research, therefore, was to examine the charring rate for different cross sections of single and double LVL members, with different connection types for the double members. The single LVL member examined was 63mm width whereas the double LVL members examined were 90mm and 126mm width. Three connection types were investigated which were nails, screws and glue. Their corresponding charring rates and burning characteristics were examined both in the small furnace provided by the University of Canterbury and in the pilot furnace at the Building Research Association of New Zealand (BRANZ) in Wellington.
The overall finding from the small furnace testing shows that the overall average side charring rate for a 30 minute fire exposure was 0.76mm/min; whereas the overall average side charring rate for a 60 minute fire exposure was 0.66mm/min. Moreover for a 30 minute fire exposure, the average bottom charring rates for nail, screw and glue connected double LVL members were 1.00mm/min, 0.83mm/min and 0.83mm/min, respectively. For a 60 minute fire exposure, the average bottom charring rates for screw and glue connected double LVL members were 0.97mm/min and 0.57mm/min, respectively. The nail connected double LVL members experienced the highest bottom charring rate as it suffered the largest bottom separation which allowed the heat to travel into the mid-span resulting in a higher bottom charring rate. Out of these three connection types, the glued connection was the best connection type.
Experimental findings were compared with the simulated results generated by the SAFIR finite element program. Experimental findings were also used to modify the spreadsheet design tool which predicts the fire resistance rating of a timber-concrete composite floor under user defined load conditions and floor geometries.
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"Determinação de um modelo para a taxa de carbonização transversal a grã para a madeira de E. citriodora e E. grandis" / Determination of model to the charring rate transversal to gran to E. citriodora and E. grandis wood.Pinto, Edna Moura 01 August 2005 (has links)
A taxa na qual a madeira se converte em carvão é determinante para a avaliação da resistência ao fogo, pois o colapso de elementos estruturais de madeira e de seus derivados quando expostos ao fogo ocorre principalmente pela redução da área resistente da seção, devido à formação de carvão. A resistência ao fogo depende, portanto, das dimensões da seção transversal que é reduzida gradualmente ao ser exposta ao fogo. Vários países têm investido em pesquisas para a caracterização e determinação da taxa de carbonização com base em diferentes espécies. Nesse trabalho são apresentados dois modelos de taxa de carbonização para a madeira de Eucalyptus das espécies citriodora e grandis, de grande interesse para aplicação estrutural e plantadas no Brasil. Um para peças de madeira com pequena dimensão (17,2 cm x 17,2 cm x 6,0 cm) e outro para as vigas estruturais (0,16 cm x 0,26 cm x 2,00 m). A curva de aquecimento adotada foi a recomendada pela ASTM E-119. / The rate at which the wood converts in char is determinant to evaluate the wood fire endurance, because the failure of wooden structural elements and its composites exposed to fire occurs through reduction of cross section. The fire resistance depends on cross sections dimensions that are gradually reduced when exposed to fire. Several countries have invested in research to determine the wood charring used for building construction that result in the establishment of values to different species. This work presents two charring rate models for citriodora and grandis species of Eucalyptus, that presents structural interests in assemblies in Brazil. One model for small pieces (17,2 cm x 17,2 cm x 6,0 cm) and the other using structural beam ( 0,16 cm x 0,26 cm x 2,00 m). The standard temperature x time curve was ASTM E-119.
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Prediction of fire origin location to wood materials charring / Gaisro kilimo vietos nustatymas pagal medinių konstrukcijų apanglėjimąLipinskas, Donatas 30 January 2007 (has links)
Most countries for constructing low-rise buildings apply mostly wood in manufacturing of various structures (bearing structures of roofs, walls, beams, columns and etc.). In cases of fire these buildings manifest mostly such evidences of burning which are called charring of wooden parts (structural elements). For investigators of fire it is relevant to find the connection of this feature with certain significant effects of fire, namely its duration or temperature, in order to be able to determine the exact location of the fire start (spot/source) as well as the cause of initiation (reason). The dynamics of fire aggravates the determining of accuracy of determining the duration of wood burning, because in wooden structures there are enacted many additional physical-chemical processes. These processes make a great influence on fire resistance of structures, on the influence of the knowledge on different fields. Well known professionals consider that the attention to charring rate under the analysis of fire is paid a too narrow one and played as inadequately considerable role. In our country there have been so far applied the remarks and recommendations of Russian scientists, regarding charring rates, there are presented generalized charring rates of wood, the particularity of coal layer measurements is discussed, the calculation of burning duration taking into account theoretical and instrumental methods , however without mentioning the influence of majority of factors... [to full text] / Daugelyje šalių mažo aukštingumo namų statybai gaminamoms įvairioms konstrukcijoms (stogų laikančiosioms konstrukcijoms, sienoms, sijoms, ir kt.) dažnai naudojama mediena. Kilus gaisrui tokiuose pastatuose, labiausiai iš visų degimo požymių yra pastebimas medžio detalių (konstrukcijos elementų) apanglėjimas. Gaisro tyrinėtojams ypač aktualu susieti šį požymį su tam tikrais svarbiais gaisro poveikiais, pvz., jo trukme ar temperatūra, kad būtų galima nustatyti tikslią gaisro kilimo vietą (židinį) bei kilimo būdą (priežastį). Gaisro dinamika apsunkina medienos degimo trukmės nustatymo tikslumą, nes medinėje konstrukcijoje vyksta daug papildomų fizikinių-cheminių procesų. Šie procesai daro didelę įtaką konstrukcijų atsparumui ugniai, o šios įtakos tyrimams reikalingos skirtingų mokslo šakų žinios. Autoritetingi specialistai mano, jog, tiriant gaisrus, apanglėjimo greitis yra nepakankamai įvertinamas ir skiriama jam per mažai dėmesio. Mūsų šalyje naudojamose Rusijos mokslininkų rekomendacijose pateikiami apibendrinti medienos apanglėjimo greičiai, aptariama anglies sluoksnio matavimo specifika, teoriniais bei instrumentiniais metodais apskaičiuojama degimo trukmė, tačiau neįvardijama svarbių veiksnių įtaka.
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Flame Spread Modelling Using FDS4 CFD modelHo, Kwok Yan (Daniel) January 2007 (has links)
This thesis examines the prediction of opposed flow flame spread in the Fire Dynamics Simulator version 4 (FDS4) Computational Fluid Dynamics (CFD) model by adapting the Lateral Ignition Flame Transport (LIFT) test procedure. It should be noted that FDS4 was all that was available at the time of the analysis despite FDS5 is now available for beta testing. This research follows on from previous work where LIFT experiments were conducted for various New Zealand timber and timber based products; those materials include Beech, Macrocarpa, Radiata Pine, Rimu, Hardboard, Medium Density Fibreboard (MDF), Melteca faced MDF, Plywood and Particle Board. The objective of this research is to investigate the accuracy of flame spread modelling in FDS4; where the prediction of opposed flow flame spread parameters from FDS4 were directly compared with the experimental results that were obtained experimentally. The standardised procedure for determining the material ignition and flame spread properties was followed and applied to simulate the LIFT test. The LIFT test apparatus was set up in FDS4 with a domain size of 0.9 x 0.3 x 0.3 metres in the x, y and z directions respectively. From the heat flux distribution along the calibration specimen, it indicated that calibration of the LIFT apparatus can be executed in FDS4 where the percentage error is within 1.2%. This report also provides the thermal transport properties (i.e. thermal conductivity and specific heat capacity) of the tested New Zealand timber and timber based products. These were determined using a transient plane source technique and subsequently these properties were entered as the surface identifications in FDS4. The ignition tests were not performed as part of the simulated LIFT test since a direct comparison with the results was required to give a more meaningful assessment. For this reason, the ignition parameters that were obtained from the previous experiments were employed to carry out the flame spread test. Due to the concept of a preheat time required by the standard test method and FDS4 being not able to preheat specimens, the temperature immediately after the preheat time was calculated and implemented for the specimens. The heat transfer problem was solved using an explicit method; where specimens were divided into 11 different nodes. Different scenarios were investigated to see the effect that the selected combustion model has on modelling flame spread. The two analytical models tested were (1) thermoplastic fuels and (2) charring fuels model. Furthermore, the flame spread was visualised using either the Mixture Fraction or the HRRPUV model in Smokeview; where the rate of flame spread for each specimen was obtained. And lastly, three different absorption coefficients (0.6, 0.7 and 0.8) for each specimen were examined; this parameter contributed significantly to the rate of flame spread as it determines the amount of heat flux being absorbed by the specimen during the time of preheating. A study of the grid size was also performed to investigate the accuracy of the FDS4 simulations with the grid size selected. It has been found that increasing the size of the grid cell does not greatly affect the flame spread results. Moisture content and heat of vaporisation input variables were also examined. From the flame spread data, moisture content does not have a significant role in modelling flame spread. However, it was indicated that the heat of vaporisation has an effect on the output of the flame spread parameters. It was determined from the sensitivity analysis that the most appropriate solid boundary condition to be used in predicting the flame spread would be thermoplastic fuels model with an absorption coefficient of 0.8. By using this scenario as the basis, the plot of the arrival time against the distance along the specimen exhibits a similar trend of flame spread with the experimental results at first, but later on, the extinction of flame front actually occurred at a much earlier stage than the experimental results showed. In general, the analyses showed that FDS4 cannot perform the LIFT test where the prediction of flame heating parameter and minimum heat flux for spread were out by more than 20% shown by the direct comparison between experimental results. However, the prediction of minimum heat flux required for ignition seems to agree with the experimental results where the percentage error is within 20%.
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"Determinação de um modelo para a taxa de carbonização transversal a grã para a madeira de E. citriodora e E. grandis" / Determination of model to the charring rate transversal to gran to E. citriodora and E. grandis wood.Edna Moura Pinto 01 August 2005 (has links)
A taxa na qual a madeira se converte em carvão é determinante para a avaliação da resistência ao fogo, pois o colapso de elementos estruturais de madeira e de seus derivados quando expostos ao fogo ocorre principalmente pela redução da área resistente da seção, devido à formação de carvão. A resistência ao fogo depende, portanto, das dimensões da seção transversal que é reduzida gradualmente ao ser exposta ao fogo. Vários países têm investido em pesquisas para a caracterização e determinação da taxa de carbonização com base em diferentes espécies. Nesse trabalho são apresentados dois modelos de taxa de carbonização para a madeira de Eucalyptus das espécies citriodora e grandis, de grande interesse para aplicação estrutural e plantadas no Brasil. Um para peças de madeira com pequena dimensão (17,2 cm x 17,2 cm x 6,0 cm) e outro para as vigas estruturais (0,16 cm x 0,26 cm x 2,00 m). A curva de aquecimento adotada foi a recomendada pela ASTM E-119. / The rate at which the wood converts in char is determinant to evaluate the wood fire endurance, because the failure of wooden structural elements and its composites exposed to fire occurs through reduction of cross section. The fire resistance depends on cross sections dimensions that are gradually reduced when exposed to fire. Several countries have invested in research to determine the wood charring used for building construction that result in the establishment of values to different species. This work presents two charring rate models for citriodora and grandis species of Eucalyptus, that presents structural interests in assemblies in Brazil. One model for small pieces (17,2 cm x 17,2 cm x 6,0 cm) and the other using structural beam ( 0,16 cm x 0,26 cm x 2,00 m). The standard temperature x time curve was ASTM E-119.
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Reaction to fire performance of wood and other building productsTsantaridis, Lazaros January 2003 (has links)
<p>The theme of this thesis is the reaction to fire performanceof wood and other building products, andparticularly thematerial fire properties time to ignition, rate of heat releaseand smoke production. These properties have been measured by asmall-scale fire test method, the Cone Calorimeter, andpresented for different types of building products.</p><p>Uncertainty analysis, included instrument and assumptionuncertainty, has been performed for the case that both O2 andCO2 are measured for calculation of the rate of heat release inthe Cone Calorimeter. The partial derivatives for theuncertainty analysis are given. The relative uncertainty forthe rate of heat release measurements in the Cone Calorimeteris between ±5% to ±10% for rate of heat releasevalues larger than about 50 kW/m2.</p><p>The time to ignition in the Cone Calorimeter is compatiblewith the time to ignition in the ISO Ignitability test, whichis the main test method for measuring time to ignition. Thetime to ignition is an increasing linear function of density.The rate of heat release in the Cone Calorimeter is dependentof material thickness and of use of retainer frame. Thematerial thickness gives the heat release curve duration andshape. Thin materials have short burning time and two maximumvalues. Thick materials have long burning time and when thematerial is thicker than about 35 mm no second maximum appears.When the retainer frame is used the actual exposed surface isreduced from 0.01 m2 to 0.0088 m2, the rate of heat release isreduced and the burning time is increased. A comparison ofresults with and without use of the retainer frame gives thenequal results when the exposed area is set to 0.0088 m2 in thecase of using the retainer frame.</p><p>The time to flashover in the full-scale room corner test waspredicted on the basis of Cone Calorimeter data at 50 kW/m2 bya power law of ignition time, the total heat release calculatedover 300 s after ignition and the density of the product. Therelation gives a simple relation to evaluate if a productreaches flashover in the room corner test.</p><p>The smoke production has also been measured in the ConeCalorimeter. The white light and the laser smoke measurementsystems have shown similar results. There is a correlationbetween Cone Calorimeter and room corner test smoke productionwhen the products are divided into groups: those that reachflashover in the room corner test in less than 10 min and thosethat have more than 10 min to flashover. Temperature profilesin wood have been measured in the Cone Calorimeter by a simpletechnique. The effect of fire protective gypsum plasterboardson the charring of wood frame members has been determined andcompared with fullscale furnace wall tests. The protectiveeffects of twenty different boards have been presented. ConeCalorimeter and furnace tests show similar charring of wooduntil the boards fall down in furnace tests. After that, thecharring of wood is higher in the furnace, because the wood isexposed directly to the fire.</p><p><b>Keywords:</b>building products, charring of wood, ConeCalorimeter, fire retardant treated wood, fire tests,ignitability, mass loss, rate of heat release, reaction tofire, smoke production, wood products</p>
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Gaisro kilimo vietos nustatymas pagal medinių konstrukcijų apanglėjimą / Prediction of fire origin location to wood materials charringLipinskas, Donatas 30 January 2007 (has links)
Daugelyje šalių mažo aukštingumo namų statybai gaminamoms įvairioms konstrukcijoms (stogų laikančiosioms konstrukcijoms, sienoms, sijoms, kolonoms ir kt.) dažnai naudojama mediena. Kilus gaisrui tokiuose pastatuose, labiausiai iš visų degimo požymių yra pastebimas medžio detalių (konstrukcijos elementų) apanglėjimas. Gaisro tyrinėtojams ypač aktualu susieti šį požymį su tam tikrais svarbiais gaisro poveikiais, pvz., jo trukme ar emperatūra, kad būtų galima nustatyti tikslią gaisro kilimo vietą (židinį) bei kilimo būdą (priežastį). Gaisro dinamika apsunkina medienos degimo trukmės nustatymo tikslumą, nes medinėje konstrukcijoje vyksta daug papildomų fizikinių-cheminių procesų. Šie procesai daro didelę įtaką konstrukcijų atsparumui ugniai, o šios įtakos tyrimams reikalingos skirtingų mokslo šakų žinios. Autoritetingi specialistai mano, jog, tiriant gaisrus, apanglėjimo greitis yra nepakankamai įvertinamas ir jam skiriama per mažai dėmesio. Lietuvoje naudojamose mokslininkų rekomendacijose [1-10] pateikiami apibendrinti medienos apanglėjimo greičiai, aptariama anglies sluoksnio matavimo specifika, teoriniais bei instrumentiniais metodais apskaičiuojama degimo trukmė, tačiau neįvardijama svarbių veiksnių įtaka. / Most countries for constructing low-rise buildings apply mostly wood in manufacturing of various structures (bearing structures of roofs, walls, beams, columns and etc.). In cases of fire these buildings manifest mostly such evidences of burning which are called charring of wooden parts (structural elements). For investigators of fire it is relevant to find the connection of this feature with certain significant effects of fire, namely its duration or temperature, in order to be able to determine the exact location of the fire start (spot/source) as well as the cause of initiation (reason). The dynamics of fire aggravates the determining of accuracy of determining the duration of wood burning, because in wooden structures there are enacted many additional physical-chemical processes. These processes make a great influence on fire resistance of structures, on the influence of the knowledge on different fields. Well known professionals consider that the attention to charring rate under the analysis of fire is paid a too narrow one and played as inadequately considerable role. In our country there have been so far applied the remarks and recommendations of Russian scientists, regarding charring rates, there are presented generalized charring rates of wood, the particularity of coal layer measurements is discussed, the calculation of burning duration taking into account theoretical and instrumental methods , however without mentioning the influence of majority of factors... [to full text]
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Reaction to fire performance of wood and other building productsTsantaridis, Lazaros January 2003 (has links)
The theme of this thesis is the reaction to fire performanceof wood and other building products, andparticularly thematerial fire properties time to ignition, rate of heat releaseand smoke production. These properties have been measured by asmall-scale fire test method, the Cone Calorimeter, andpresented for different types of building products. Uncertainty analysis, included instrument and assumptionuncertainty, has been performed for the case that both O2 andCO2 are measured for calculation of the rate of heat release inthe Cone Calorimeter. The partial derivatives for theuncertainty analysis are given. The relative uncertainty forthe rate of heat release measurements in the Cone Calorimeteris between ±5% to ±10% for rate of heat releasevalues larger than about 50 kW/m2. The time to ignition in the Cone Calorimeter is compatiblewith the time to ignition in the ISO Ignitability test, whichis the main test method for measuring time to ignition. Thetime to ignition is an increasing linear function of density.The rate of heat release in the Cone Calorimeter is dependentof material thickness and of use of retainer frame. Thematerial thickness gives the heat release curve duration andshape. Thin materials have short burning time and two maximumvalues. Thick materials have long burning time and when thematerial is thicker than about 35 mm no second maximum appears.When the retainer frame is used the actual exposed surface isreduced from 0.01 m2 to 0.0088 m2, the rate of heat release isreduced and the burning time is increased. A comparison ofresults with and without use of the retainer frame gives thenequal results when the exposed area is set to 0.0088 m2 in thecase of using the retainer frame. The time to flashover in the full-scale room corner test waspredicted on the basis of Cone Calorimeter data at 50 kW/m2 bya power law of ignition time, the total heat release calculatedover 300 s after ignition and the density of the product. Therelation gives a simple relation to evaluate if a productreaches flashover in the room corner test. The smoke production has also been measured in the ConeCalorimeter. The white light and the laser smoke measurementsystems have shown similar results. There is a correlationbetween Cone Calorimeter and room corner test smoke productionwhen the products are divided into groups: those that reachflashover in the room corner test in less than 10 min and thosethat have more than 10 min to flashover. Temperature profilesin wood have been measured in the Cone Calorimeter by a simpletechnique. The effect of fire protective gypsum plasterboardson the charring of wood frame members has been determined andcompared with fullscale furnace wall tests. The protectiveeffects of twenty different boards have been presented. ConeCalorimeter and furnace tests show similar charring of wooduntil the boards fall down in furnace tests. After that, thecharring of wood is higher in the furnace, because the wood isexposed directly to the fire. Keywords:building products, charring of wood, ConeCalorimeter, fire retardant treated wood, fire tests,ignitability, mass loss, rate of heat release, reaction tofire, smoke production, wood products / <p>NR 20140805</p>
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BRANDSKYDDAT TRÄ : Jämförelse mellan obehandlat, brandskyddsmålat och brandskyddsimpregnerat träNeumann, Dorothea January 2015 (has links)
Environmental issues and the housing shortage is an ongoing debate among politicians. Wood is a building material that Sweden has plenty of and it is a material that, according to research, does not contribute to as much carbon dioxide emissions during production, compared to other construction materials such as concrete and steel. Therefore the demand for timber, in both facade claddings and external wall constructions, is increasing. In light of this, the purpose with this degree project is to study different fire protection methods for wood and compare it to untreated wood. Collecting the facts and information for this degree project at Mälardalens University, is done through literature studies, surveys, and two experiments conducted on two selected fire retardants. The experiments were conducted to test untreated, fire protection impregnated and wood with fire proof paint. One of the experiments tested the load-carrying capacity of the beams after being charred with a gas burner. The other experiment investigated the surface layer and measured the fire spread rate and both experiments tested the fire resistance. The experiments that were conducted concluded that out of the three different methods for facades and beams, fire protection impregnation was the best choice in all five chosen categories: load-carrying capacity, fire resistance, surfaces, environmental impact and health safety for workers. / Miljöfrågan och bostadsbristen är två pågående debatter bland politikerna. Ett byggmaterial som både är miljövänligt och lätt att bygga med är trä. Det är ett byggmaterial som Sverige har gott om och enligt forskning bidrar det inte med lika mycket koldioxidutsläpp vid produktionen jämfört med andra konstruktionsmaterial som betong och stål. Enligt äldre bygglagstiftningar var det enbart tillåtet att bygga hus med två våningar i trä. Det var godkänt att bygga hus med tre våningar om den nedersta våningen bestod utav sten och de två översta i trä. Den nya bygglagstiftningen har inga begränsningar på att använda trä i ytterväggar, oberoende av byggnadsklass så länge de uppfyller funktionskraven. Byggsektorn har varit medveten om att de fick bygga flervåningshus i trä men inte hur det skulle utföras och samtidigt uppfylla bygglagstiftningens krav. Resultatet av ändringarna i bygglagstiftningen, Boverkets byggregler, ökade efterfrågan och utbudet på brandskyddsmedel till trä. De vanligaste produkterna som finns ute för konsumenten är brandskyddsfärg och brandskyddsimpregnering. Trä kan genom brandskyddsimpregnering eller brandskyddsfärg få en brandteknisk klass enligt det europeiska systemet, EN 13501-1, upp mot B-s1,d0 som är högre än för obehandlat trä, Ds1, d0. Tekniskt sett går det att bygga Br1-byggnader med obehandlat trä, dock så krävs det ett antal åtgärder för att uppfylla Boverkets byggreglers funktionskrav, till exempel att installera automatiska släcksystem eller enbart ha trä på en begränsad del av fasaden. Med brandskyddsbehandling går det idag endast att uppnå brandteknisk ytskiktsklass B-s1,d0, vilket inte är tillräckligt enligt Boverkets byggregler som kräver lägst obrännbara fasadbeklädnader i ytskiktsklass A2-s1,d0 för att uppfylla allmänna råden. Fasadbeklädnader av trä, oavsett brandteknisk klass, kan testas med provmetoden SP FIRE 105 och därmed uppfylla föreskriftens krav på ytterväggskonstruktioner med avseende på brandspridning längs fasadytan. Syftet med arbetet är att jämföra olika brandskyddsmetoder av trä och undersöka vilken eller vilka som är bäst lämpad att använda i flervåningshus ur bland annat miljö-, arbetsmiljö- och brandsynpunkt. Detta uppnås genom en litteraturstudie som fokuserar på ämnet brandskyddsmetoder av trä och genom två försök genomfördes för att testa obehandlat, brandskyddsimpregnerat och brandskyddsmålat trä. Ett försök testade bärförmågan efter brandpåverkan, andra undersökte ytskikt, och båda försöken testade brandmotstånd. Bärförmågan testades genom att brandpåverkade reglar blev utsatta för en central punktlast i en Instron- maskin. Ytskikten prövades genom ett enklare försök baserad på testmetoden SP FIRE 105 på tre fasader. En obehandlad, en brandskyddsimpregnerad och en brandskyddsmålad. Mätningar och dokumentation gjordes med bland annat mätinstrument som plattermoelement och filmkamera. Båda typerna av brandskyddsmetoder kräver en kemisk framställning som varken är bra för naturen eller människan. Produktionen är automatiserad och därmed inte någon risk för någon människa. Den färdiga produkten är varken skadlig för miljön, människor eller djur, sålänge inte produkterna förtärs i större omfattning. Resultatet från undersökningen av de tre olika fasaderna visade att det brandskyddsimpregnerade virket klarade sig bäst i alla fem kategorier: bärförmåga, brandmotstånd, ytskikt, miljöpåverkan och arbetsmiljö. Slutsatsen är av det två typer av brandsskyddsmedel för trä som testades, är brandskyddsimpregnering den mest lönsammaste alla fem kategorier. Produkten är lätthanterad, avger inga farliga gaser och är i snitt inte dyrare än det obehandlade materialet. Dock är det viktigt att tänka på brandskyddsarbete och inte släppa på säkerheten för att konstruktionen byggs med brandskyddsimpregnerat trä.
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Temperature distribution and charring penetrations in timber assemblies exposed to parametric fire curves : Comparisons between tests and TASEF predictionsAndersson, Isac, Ek, Niklas January 2017 (has links)
Four furnace tests have been performed using two different parametric fire curves and the results are compared with computer simulations and Eurocode calculations. What differentiates the parametric fire curve from other fire curves is in particular the cooling phase, something that has proven to be hard to model for timber structures. A literature study and computer simulations were followed by experimental work performed at SP Wood Building Technology in Stockholm. The computer simulations were performed using the computer code TASEF. The predictions from TASEF were compared with measurements from the fire tests to evaluate how well the program can predict temperature distribution using a parametric fire curve. The four fire tests were executed at SP Wood Building Technology, glued laminated timber beams were used in all tests. When preparing the test specimens thermocouples were installed to measure temperature distribution, the thermocouples were installed in drilled holes. A deviation study regarding these drill-holes was performed as a part of the preparations. The temperature distributions measured during the tests were compared with the temperature distribution predicted by TASEF. Charring rate and charring depth were obtained from the fire tests, from the TASEF simulations but also by using equations given in the Eurocode. Since TASEF simulates temperature distribution and not charring depth, the 300 °C isotherm was assumed to represent the charring depth. The results from all three methods were compared and evaluated. The agreement between experiments and TASEF predictions regarding temperature distribution and charring depth were in general very good. Parametric fire curves with opening factors of 0.02 m1/2 and 0.04 m1/2 were used in four fire tests. TASEF performed more accurate predictions regarding the temperature distribution for the small opening factor but looking at the charring depth the predictions were better for the bigger opening factor. It is recommended to perform further studies and find out the reason for this behaviour. Comparing the charring depths measured at the tests with values calculated using Eurocode 5 there were some differences in charring depths. Charring depths for the horizontal direction of the beams were much alike, but when comparing the charring depths for the vertical direction there is a significant difference. The equations regarding charring depth for wood exposed to parametric fire curves in Eurocode 5 underestimate the charring depth. It is recommended to evaluate these equations further. For one of the timber beams delamination occurred, this has previously been assumed not to occur to glued laminated beams. More studies should be performed regarding delamination of glued laminated beams exposed to fire. / Fyra brandtester i en brandprovningsugn har genomförts med två olika parametriska brandkurvor och resultatet har jämförts med datorsimuleringar och Eurocode-beräkningar. Det som särskiljer parametriska brandkurvor från andra brandkurvor är nedkylningsfasen, något som har visat sig svårt att modellera för träkonstruktioner. Litteraturstudier och datorsimuleringar följdes av experimentellt arbete som utfördes vid SP Träbyggande och Boende i Stockholm. Datorsimuleringarna har utförts med datorkoden TASEF. Simuleringsresultat från TASEF jämfördes med mätningar från brandtesterna för att utvärdera hur bra TASEF kan förutse temperaturdistributionen då en parametrisk brandkurva används. De fyra brandtesterna förbereddes och utfördes på SP Träbyggande och Boende, limträbalkar användes i samtliga tester. När testbalkarna förbereddes inför brandtesterna installerades termoelement för att mäta temperaturdistributionen. Termoelementen installerades i borrhål. Som en del av förberedelserna gjordes en avvikelsestudie för dessa borrhål. Temperaturdistributionen som uppmättes under testerna jämfördes med temperaturdistributionen från TASEF-simuleringar. Från brandtester, TASEF-simuleringar och från ekvationer i Eurocode erhölls förkolningshastighet och förkolningsdjup. Eftersom TASEF simulerar temperaturer och inte förkolningsdjup användes 300 °C isotermen som då antogs representera förkolningsdjupet. Resultatet från alla tre metoder jämfördes och utvärderades. Generellt stämde temperaturdistributionen och förkolningsdjupen från TASEF-simuleringarna väldigt bra överens med de experimentella resultaten. Under testerna användes parametriska brandkurvor med öppningsfaktorer av 0.02 m1/2 och 0.04 m1/2. TASEF simulerade mer noggranna resultat gällande temperaturdistributionen för kurvan med den lägre öppningsfaktorn medan simuleringar för kurvan med den högre öppningsfaktorn gav bättre resultat för förkolningsdjupet. Det rekommenderas att göra fler studier för att ta reda på anledningen till detta beteende. Genom att jämföra förkolningsdjup som uppmättes efter brandtesterna med beräknade värden från Eurocode förekom vissa skillnader. Förkolningsdjup för bredden av balkarna var likartade, medan förkolningsdjupet för höjden av balkarna hade en signifikant skillnad. Ekvationerna i Eurocode underskattade förkolningsdjupet, det rekommenderas därför att utvärdera dessa ekvationer ytterligare. För en av limträbalkarna inträffade delaminering, detta har tidigare antagits vara osannolikt för limträbalkar. Fler studier borde utföras angående delaminering av limträbalkar exponerade för parametriska brandkurvor.
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