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- Brandon, Daniel, et al.
(författare)
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Fire Safety of CLT Buildings with Exposed Wooden Surfaces
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An increasing number of tall buildings made of CLT have been built in recent years. Current architectural trends involve having visible timber surfaces in these tall CLT structures. This results in new fire safety challenges, especially because fire service interference is increasingly difficult for increasingly tall buildings. Recently, a number of research projects involving large scale compartment fire testing studied the development of fires in (1) compartments with a fully encapsulated CLT structure and (2) compartments with exposed CLT surfaces. The studies have shown that sufficient gypsum board protection can avoid the involvement of CLT in a fire. However, fall-off of the base layer of gypsum boards during can result in continuous fires that do not extinguish without fire surface interference, as during fall-off large areas of initially protected timber surfaces start to contribute as fuel to the fire. If CLT is exposed to a fire, fire induced delamination of CLT (also lamella fall-off or char fall-off) could occur due to weakening of bond lines within the CLT. During fire induced delamination the exposed lamella falls from the CLT and a new relatively cold timber surface becomes exposed to potentially high temperatures, which effectively makes additional fuel suddenly available to a fire. Very recent studies involved the development of CLT products that are not subject to delamination. The studies indicate that the use of (a) sufficient fire protection, (b) CLT products with thermally resistant adhesives and (c) a limit regarding the surface area of CLT that can be exposed, result in fires that decay and eventually self-extinguish.This paper reviews the studies and includes a summary of conclusions.
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- Brandon, Daniel, et al.
(författare)
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Förslag för brandskydd i flervånings trähus
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport ger förslag på lösningar för brandskydd i höga trähus. De förslag som ges är inte fullständiga och andra åtgärder kan vara aktuella för att få till ett bättre brandskydd i höga trähus. De förslag som presenteras baseras på arbetet i forskningsprojektetBrandskydd i höga trähus, som finansierats av Brandforsk (Brandforsk projekt 301-152) och Svenskt Trä och denna rapport är till stora delar en översättning av RISE report 2018:43 "Mitigation of fires in multi-storey timber buildings – statistical analysis and guidelines for design" av Daniel Brandon, Alar Just, Petra Andersson och Birgit Östman.Brandnormer inriktas i första hand på personsäkerhet, men i höga och stora byggnader blir egendomsskyddet allt viktigare. De förslag som ges här baseras främst på analys av stora skador i USA. De viktigaste punkterna är att begränsa1. Direkt brand- och rökspridning mellan brandceller via:a. dörrar, väggar och bjälklagb. anslutningar mellan byggnadselementc. genomföringar i väggar och bjälklagd. installationer i väggar och bjälklag2. Brand- och rökspridning genom hålrum:a. i brandcellsavskiljande byggnadselementb. i fasader och yttertak3. Utvändig brand- och rökspridning:a. längs fasadens ytab. genom fönsterc. genom ventilationsöppningar (t ex vid takfot)d. på vindar
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- Brandon, Daniel, et al.
(författare)
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High-Fire-Resistance Glulam Connections for Tall Timber Buildings
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Tall timber buildings generally require fire resistance ratings of 90 minutes, 120 minutes or more. The vast majority of fire tested structural timber connections, however, did not reach a fire resistance that was relevant for these buildings. Commonly timber connections between glued laminated timber members comprise of exposed steel fasteners, such as bolts, screws, nails and dowels. However, it has previously been concluded that connections with exposed steel fasteners, generally do not achieve fire resistance ratings of 30 minutes and are, therefore, inadequate to be implemented in tall timber buildings without fire encapsulation. The research project presented in this report consists of four connection fire tests that are designed to achieve structural fire resistance ratings of 90 minutes, using different design strategies. This goal was achieved for all tested column-beam connections. A single test of a moment resisting connection did not lead to a fire resistance rating of 90 minutes, due to timber failure at the smallest cross-section after 86 minutes. The low temperature of the steel fasteners and the limited rotation of the connection, however, suggest that the connection would have been capable of achieving a 90 minutes fire resistance rating if larger beam cross-sections would be used.
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- Brandon, Daniel, et al.
(författare)
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Limiting flame spread rates in large compartments with visible timber ceilings
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The number of tall buildings combining both a visible mass timber structure and large open floor plans is growing rapidly introducing new fire safety challenges. One risk is that of very rapid flame spread in the ceiling, originating from a severe but localized fire, resulting in fires where the majority of large compartments burn simultaneously. Such phenomena have been observed in both tests and accidents, but knowledge of effective mitigation without the use of sprinklers is scarce. In Europe, this problem is commonly addressed in construction by complying to prescriptive rules of reaction-to-fire classification of linings. The reaction-to-fire classification, primarily based on the single burning item (SBI) test of EN13832, characterizes the material’s contribution to a fire in the very initial phase of the fire. Treatments can be used to improve the reaction-to-fire class of mass timber, which will reduce the risk of substantial fire development. Fires can, however, develop and grow large even without the contribution of lining materials. For this reason, and in light of the recent findings of research of large open floor plan compartments, it is of interest to assess the effectiveness of treatments to reduce the risk of rapid flame spread. Therefore, eight tests in 18.0 × 2.3 × 2.2 m3 compartments were performed. Six had exposed timber surface with a clear coating or impregnation in the ceiling, complying with a reaction-to-fire class B and two served as untreated timber and non-combustible reference tests. The fire source, representing a fire in moveable fuel, was severe enough (3 - 3.7 MW) for flame impingement on the ceiling. The rate of at which wood ignited from the heat in the ceiling, the temperature development at different heights, as well as external flaming were assessed and were used as indicators of performance. Additional indicators were the estimated tenability and ceiling char depths throughout the compartment. The untreated timber and the non-combustible ceiling represented the two extremes for most indicators with the class-B treated timber surfaces falling in between. Close to the fire source, the test indicators for treated timber surfaces performed similar to those of the untreated timber surface while the non-combustible ceiling performed significantly better. With increasing distance from the fire source, indicators from treated timber tests more resembled the non-combustible ceiling. This behavior was noticed for all types of indicators. With increasing distance from the fire source, the fire exposure is naturally less severe and thus, more similar to the small burner exposure used in SBI-testing which the treatments were developed against. Both final charring depth and temperature developments for ignition and tenability were clearly improved by the treatment, but the SBI test results (FIGRA and THR600s) did not correlate well to the compartment test indicators (Figure 92 andFigure 93). Nevertheless, using treatments assessed by SBI is a common strategy to mitigate fire spread in newly constructed mass timber buildings and practitioners should be aware that while the treatments have significant effects on the flame spread they are not to be treated as incombustible. We propose that addressing the ceiling spread problem requires an additional indicative test with more severe exposure than the SBI test setup. The impregnated timber experienced loss of integrity due to substantial shrinkage of the timber during the severe exposure. Such phenomena were not captured in the SBI testing. Comparisons of performance of the impregnated specimens indicates that it can be beneficial for the performance to implement more impregnation than needed for reaction-to-fire class B. Whether this holds for all treatments cannot be concluded.
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| 7. |
- Brandon, Daniel, 1985-, et al.
(författare)
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Mitigation of fire damages in multi-storey timber buildings : Statistical analysis and guidelines for design
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The number of multi-storey timber buildings has increased during the last twenty years. Recent well-known fires in London, Dubai and Brazil, although not in timber buildings, have increased concerns regarding large fire spread and high damage fires. As timber is a combustible material, concerns have been expressed regarding property safety and it has been questioned whether fire damage is more significant in buildings with timber as the main structural material than in other types of buildings. This report includes a statistical study of data of fires in multi-storey timber buildings in New Zealand and an analysis of high damage fires that occurred in multi-storey timber buildings in the USA. The data from New Zealand showed no significant difference between share of fires that had flame damage out of the compartment of origin in (a) multi-storey timber buildings that were constructed in or later than 1992 and (b) other types of multi-storey buildings that were constructed in or later than 1992. Fires in multi-storey timber buildings that were constructed before 1992 spread more frequently to neighbouring compartments than fires in other multi-storey timber buildings constructed before 1992. Data of high damage fires occurring in multi-storey timber buildings in the USA indicated that outdoor fire spread is the most common cause for large fire spread. Additionally, the data indicates that high water damage is most often caused by fire service interference and is significantly less often related to sprinkler activation.Based on the analysis of fire spread of high damage fires in the USA, guidelines are given in the report to limit (1) outdoor fire spread, (2) fire spread through cavities, and (3) fire spread directly from a fire compartment to a neighbouring fire compartment. A number of these guidelines were evaluated using a fire test of a two-storey timber structure.
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| 8. |
- Brandon, Daniel, et al.
(författare)
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Parametric fire design – zero-strengthlayers and charring rates
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the field of fire safety engineering performance based design methods are increasingly used to demonstrate that building designs are safe. However, performance based design is not commonly used for the design of timber structures, as there are not many relevant assessment methods available (Östman et al. 2010). For assessment whether the design of a building meets certain criteria, a design fire scenario is needed. Design fires often describe the temperature throughout a fire and are often based on dimensions, ventilation conditions and the fuel load of the compartment. Parametric fires are such design fires, used for structural calculations corresponding to post-flashover fires in compartments, based on the compartment’s dimensions, ventilation openings, lining materials, and the fuel load. Eurocode 1 (EN1991-1- 2:2004) includes parametric fires. Annex A of Eurocode 5 (EN1995-1-2:2004) offers calculation methods to determine charring rates of timber under parametric fire exposure, which depend mostly on the compartment’s ventilation opening sizes. However, Annex A is not accepted for use in all European countries, as the provided charring rates are questioned. Additionally, there are some parameters missing for calculations of structures exposed to parametric fires, namely: (1) notional charring rates, which take into account an increased char depth at the corners of small crosssections and (2) zero-strength-layers, which take into account a strength reduction of uncharred but damaged wood in the structural member. This paper presents an experimental study performed to determine one-dimensional, notional charring rates and zero-strength-layers corresponding to a range of parametric fire curves.
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| 9. |
- Buchanan, Andrew, et al.
(författare)
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Fire safety in timber buildings
- 2022
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Ingår i: Fire Safe Use of Wood in Buildings. - Boca Raton : CRC Press. - 9781032040394 - 9781032040417 - 9781003190318 ; , s. 33-62
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Bokkapitel (refereegranskat)abstract
- This chapter provides an overall description of the strategy for delivering fire safety in timber buildings. As in the design of all buildings, the goals are to provide life safety for occupants, safe access for firefighters and protection of affected property. It is essential to control the severity and duration of any accidental fire and prevent it from spreading elsewhere in the building. An important design objective for timber buildings is to control the burning or charring of exposed timber or protected timber, because this can add to the fuel load, and it will reduce the load capacity of structural timber members due to loss of cross-section. Many of the topics introduced here are expanded on in the following chapters.
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| 10. |
- Dagenais, Christian, et al.
(författare)
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Fire Safe Use of Wood in Buildings : Global Design Guide
- 2023
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Ingår i: World Conference on Timber Engineering. - : World Conference on Timber Engineering (WCTE). - 9781713873297 ; , s. 4627-4635
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Konferensbidrag (refereegranskat)abstract
- Building codes around the globe dictate the design and construction of buildings. For most buildings, designers will follow prescriptive code provisions to demonstrate code compliance. However, some buidling codes allow the use of performance-based design to demonstrate code compliance. Performance-based design is usually more complex but allows for greater flexibility in the use of materials and systems. Regardless of the code compliance methods, the combustibility of timber structures and wood products needs to be well understood and properly accounted for in building designs. This paper describes the develpment of a new international guidance document on fire safety in timber building within the Fire Safe Use of Wood (FSUW) network, written by 13 lead authors assisted by more than 20 experts in over a dozen different countries.
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