| 1. |
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| 2. |
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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 11. |
- Dagenais, Christian, et al.
(författare)
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Timber structures and wood products
- 2022
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Ingår i: Fire Safe Use of Wood in Buildings. - Boca Raton : CRC Press. - 9781032040394 - 9781032040417 - 9781003190318 ; , s. 1-32
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Bokkapitel (refereegranskat)abstract
- This chapter presents an overview of the occupancy groups in buildings and the types of timber structures that can be used to design and construct these buildings. Obviously, the types of construction presented in this chapter may have different names in different countries, but the fundamentals and design principles remain essentially the same.A description of the various timber and engineered wood products available on the market is also provided. It summarises the manufacturing processes, typical end uses and product certifications, when applicable. Given the large variety of timber products around the globe, some of the engineered wood products presented herein may not be available in all countries.This chapter is not intended to provide an exhaustive historical review of timber constructions and wood products, but rather aims at providing sufficient information for designers, builders, building officials/authorities and fire services to better understand and differentiate the various wood products and timber building systems available.
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| 12. |
- Jalas, Raido, et al.
(författare)
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Analysis of fires in buildings in Estonia
- 2015
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Ingår i: Proceedings of the 1st European Workshop Fire Safety of Green Buildings. - : Shaker.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 13. |
- Just, Alar, et al.
(författare)
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Brandstopp i byggnadskonstruktioner : Resultat från SBUF projekt 12993
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Bristande brandteknisk funktion hos byggnadstekniska detaljlösningar är ofta en starktbidragande orsak till brandspridning. Flera incidenter de senaste åren visar tydligt att byggsystemmed hålrum kan ha stor inverkan på brandförloppet och medföra stora egendomsskador i allatyper av byggnader. Befintliga rekommendationer om att brandstopp måste installeras i hålrumför att hindra att dolda bränder uppstår och sprids mellan brandceller följs tyvärr ofta inte inompraktiskt byggande.Syftet med projektet är att utveckla en lämplig metodik för att verifiera funktionen hos olikatyper av brandstopp i byggnader, att dokumentera funktionen hos några typer av brandstoppenligt relevant metodik samt att ge underlag för riktlinjer om hur brandstopp ska utformas ochanvändas. Resultaten ska även kunna användas för att bedöma befintliga detaljlösningar.Arbetet har inriktats främst på brandstopp för hålrum i modulhus. Olika typer av brandstopp försådana hålrum har studerats bland annat genom provningar i modellskala. Befintligprovningsteknik har vidareutvecklats och en reviderad metodik har föreslagits.Som ett första resultat för praktisk användning har riktlinjer tagits fram för hur brandstopp skautformas och användas i modulkonstruktioner. De främsta målgrupperna är bygg- ochbyggmaterialindustrin samt brandkonsulter
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Just, Alar, et al.
(författare)
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CLT compartment fire test
- 2018
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Ingår i: WCTE 2018 - World Conference on Timber Engineering.
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Konferensbidrag (refereegranskat)abstract
- New high-rise timber buildings are planned to be built in the near future all around the world. The fire protection concepts are not always considering natural fire scenarios. As timber is a combustible material, it can contribute to the fire within and outside of the fire compartment. For buildings with cross-laminated timber (CLT) elements the possible fall-off of lamellas should be considered because of the risk for second flashover, which can lead to a continuous fire. However, in case fire service interference or sprinkler activation is absent or inefficient, it may be necessary to design a building so that it leads to a decaying fire. Additionally, it is important to limit fire spread to neighbouring compartments. This paper discusses a compartment test of a two-story building made of CLT performed in Estonia to study delamination behaviour and consequences in compartments with realistic ventilation conditions. State-of-the art solutions to limit fire spread from the first floor into the second floor were applied. This involved robust design of connections, penetrations through the compartment boundary and the façade. The paper provides a description and analysis of the test.
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| 18. |
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| 19. |
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| 20. |
- Just, Alar, et al.
(författare)
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Execution of timber structures and fire safety
- 2016
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Ingår i: WCTE 2016. - 9783903024359 ; , s. 5555-5562
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Konferensbidrag (refereegranskat)abstract
- Fire safety is one of the six essential performance requirements to consider when building timber structures. Fire safety has to be proven for the whole building process and the end use of the building. On the building site during the execution there might be an increased risk for fire spread because of large amounts of unprotected timber and relatively open structures. Work processes dealing with high temperatures, smoking, vandalism or other reasons can lead to ignition of timber and end up with serious damages. Fire safety on the building site should be handled from the very beginning to the final stage of execution. During the execution the designed solutions have to be checked and followed. This paper gives the background and principles that should be considered in a new Nordic standard for execution of timber structures in terms of fire safety.
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| 21. |
- Just, Alar, et al.
(författare)
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Failure times of gypsum boards
- 2010
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Ingår i: Proceedings of the Sixth International Conference. - : DEStech.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 22. |
- Just, Alar, et al.
(författare)
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Failure times of gypsum plasterboards
- 2010
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Ingår i: Interflam 2010: Proceedings of the twelfth international conference. - : London, UK.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 23. |
- Just, Alar, et al.
(författare)
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Fire protection abilities provided by gypsum plasterboards
- 2012
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Ingår i: Proceedings of World Conference on Timber Engineering 2012 (WCTE 2012). - : WCTE 2012 Committee. ; , s. 540-544
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Konferensbidrag (refereegranskat)abstract
- Gypsum plastcrboards and gypsum fibrcboards arc often used as cladding on timber frame assemblies. Being the first layer on the fire exposed side, the protective properties of the boards are important for the whole assembly, especially for load bearing structures. Different design rules for the protection effect of gypsum plastcrboards arc presented and compared in the paper.
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| 24. |
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| 25. |
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| 26. |
- Just, Alar, et al.
(författare)
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Fire Stops in Buildings
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In a statistical study performed by the London fire brigade in the Real Fires Database it was found that out of 30 086 fires occurring between 2009 and 2011, fire spread beyond the floor of origin through gaps or voids occurred in 92 cases. This illustrates that the phenomenon is relatively rare. However, it can lead to severe property damage. Fires can spread invisibly within cavities of the structure, which has led to problems concerning the extinguishment of the fire. Cavity barriers function is to stop the fire spread through cavities. However, these cavity barriers have not always been effective.This report is the result of a study that aimed to:1. Develop a robust testing method for cavity barriers for cavities with combustible materials within walls, floors and other elements in buildings.2. Provide guidelines for the materials, installation, positioning, detailing and location of the cavity barriers.Additionally, a preliminary study is performed to assess some extinguishing strategies.Based on a study of characteristics of cavity fires, current standard fire tests for cavity barriers were revised for the use in cavities with combustible materials. From tests following the revised methodology, guidelines regarding the dimensions, installation and fire stopping design are provided.
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| 27. |
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| 28. |
- Just, Alar, et al.
(författare)
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Improved fire design model for cross-laminated timber and glulam
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Adhesives state the essential prerequisite for manufacturing large timber construction elements from rigidly bonded solid wood boards of growth and processing bound limited dimensions. In the first two decades after the invention of glulam up to the 1930s, adhesives based on natural organic substances like blood and proteins were used. Such adhesives can have high dry strength but are weak when applying water or temperature. These adhesives were then replaced by synthetic ones, firstly in the early 1930s by (phenol )-resorcinol-formaldehyde (RF/PRF) adhesives and then by urea-formaldehyde (UF) adhesives. Numerous tests have shown that the boiling water resistant duroplastic RF/PRF adhesives are very stable at high temperatures up to/beyond the charring of wood (Dorn and Egner, 1967; Klippel 2014). Contrary hereto, the UF adhesives later classified in Europe as type II adhesives have significantly reduced water resistance (e.g. Raknes (1997) and are less temperature stable and fire resistant, although the latter was not communicated sufficiently. The RF-, PRF- and UF- adhesives were exclusively used up until the 1980s when the presently existing timber standards for “cold” and fire design were being developed. From the 1980s onwards, adhesives with various chemical compositions have been added to the market. Firstly the duroplastic melamine-urea-formaldehyde and pure melamine formaldehyde (MUF/MF) adhesives, followed in the mid-90s by the moisture-hardening one-component polyurethane (1C-PUR) adhesives, then followed by the emulsion-polymer isocyanate (EPI) adhesives. In order to speed up curing times, being of utmost high economic importance, significant amounts of polyvinyl acetate (PVAc) have been added to the hardeners of MUF adhesives with drawbacks on temperature stability. Each of the developed adhesives has its advantages and disadvantages regarding strength, water and/or temperature resistance, application robustness and price. According to EN 1995-1-2:2004, chapter 3.5, the behaviour of a bond line in fire may not be considered explicitly if the bond line is made of phenol-formaldehyde and aminoplastic, Type I adhesives, according to EN 301. Regarding the general principle that adhesives shall produce joints of such strength that the integrity of the bond is maintained in the assigned fire resistance period, a footnote hints at the point that some adhesives show softening considerably below the charring temperature of wood.
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
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| 34. |
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| 35. |
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| 36. |
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| 37. |
- Just, Alar, et al.
(författare)
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SMART HOUSING SMÅLAND : Optimizing the fire protection of massive timber structures
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A research project to optimize gypsum protection of CLT or other mass timber materials was performed by RISE. The project included 5 intermediate scale furnace fire tests of CLT protected with a fire rated gypsum board. The pattern of the gypsum screws was varied in the tests to allow for a comparative study. The comparisons indicated that fall-off of gypsum boards can be delayed significantly by changing positions of screws and the spacing between them.
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| 38. |
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| 39. |
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| 40. |
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| 41. |
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| 42. |
- Kauniste, Maarja, et al.
(författare)
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Assessment on Strength and Stiffness Properties of Aged Structural Timber
- 2024
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Ingår i: Journal of Sustainable Architecture and Civil Engineering. - : Kauno Technologijos Universitetas. - 2029-9990. ; 34:1, s. 62-74
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Tidskriftsartikel (refereegranskat)abstract
- Despite the growing popularity of wood and wood-based products in the construction industry, there has been insufficient focus on assessing the condition, preservation, and potential reuse of existing timber. While numerous standards evaluate the quality of freshly sawn timber, there is currently no standardized system for assessing the strength properties of aged and reused timber. The lack of these guidelines is also one of the reasons the results obtained in numerous research are often fluctuating, and we cannot draw clear conclusions. The matter is further complicated by the lack of data on old in-situ wood and its exploitation, which would help to evaluate its condition. Consequently, there is a real practical need to assess the condition of old timber to avoid unnecessary demolition and the loss of valuable and structurally sound building material. What sets this study apart from others is that, in addition to destructive testing, the 4-point non-destructive (ND) bending tests were conducted on all four faces of test specimens. This provided an opportunity to assess the wood visually and then find connections to associate external characteristics with real properties. This methodology aimed to determine whether it is feasible to visually assess the most practical way to use wooden elements in construction. If this question arises, which face of the beam would be better suited for the tension side and which for the compression side? The old timber used in testing originated from an old library building located on Vaksali Street, Tartu, Estonia and is estimated to be about 120 years old. This paper investigates and compares the collected data with a Nordic standard for grading fresh-sawn timber and two established Italian standards for visually assessing aged timber. This comparison contributes to developing a standardized framework for future visual assessments. ND and destructive four-point bending tests were performed to validate and find appropriate visual characteristics to determine the strength and stiffness of the timber elements. The primary goals of this study were first to compare the results obtained from existing ND methods with actual results and secondly to provide guidelines for better visual grading of wood in the future, based on Nordic Standard INSTA 142 (2010) and Italian standards UNI 11119 (2004) and UNI 11035 (2010) Contrary to previous research conclusions, the visual assessment results yielded unexpected outcomes. The results show that the grading standards significantly underestimated the real strength of the wood, and even more, none of the visual assessments overestimated the real strength of the specimens. Therefore, based on prior research and the findings derived from this study, there is evident a substantial potential for extensive development and optimization within this field.
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| 43. |
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| 44. |
- Mäger, Katrin Nele, et al.
(författare)
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Improved fire design model for walls and floors with I-joists
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Wooden I-joists, being factory-made ultra-light and highly optimised products, are typically used as the load-bearing elements in timber frame assemblies (TFA), which consist of a combination of material layers – sheeting boards (claddings) and cavities which may be partially or completely filled with insulation. The materials used in conjunction with a timber member in a TFA affect the heating of the timber member. The joists consist of flanges (made of sawn wood, LVL or glulam) and a web (made of a wood - based board). Fire resistance of such wooden structural products is a complex matter. However, the current European design standard for timber structures in fire – Eurocode 5 Part 1-2 (2004) provides no guidance for I-joists. The fire resistance of wooden I-joists has been previously investigated by König (2006) and Schmid et al. (2011), who developed calculation models to analyse the load-bearing capacity of wooden I-joists exposed to fire for floors. There have been significant changes in the variety and types of materials used in conjunction with I-joists. Therefore, the application of these models is limited nowadays. Additionally, they focus on the reduced properties method. Only the effective cross-section method will be included in the revised Eurocode 5 Part 1-2. This report describes the unified model for wooden I-joists in both wall and floor assemblies which follows the philosophy of the effective cross-section method. Additionally, it should be used with all types of cavity insulation and fire protection systems. The unified I-joists model aims to be introduced to the new revised Eurocode 5 Part 1-2. Two phenomena have to be considered according to the ECSM: charring and mechanical resistance. It is assumed that the charring of wood is a material characteristic which is not dependent on the orientation of the structure (wall or floor). The charring of the flanges is primarily dependent on the cladding material and thickness. After the failure of the claddings, the charring is influenced by cavity insulation. Gypsum plasterboards as cladding and stone and glass wool as cavity insulation have been tested and analysed. A large number of thermal simulations have been analysed to investigate the influence of various factors (e.g. flange size, cavity insulation material, protective boards) on the charring behaviour of the fire-exposed flange and the web. The combination of different materials and the slender nature of I-joists makes their fire resistance a complicated issue. The thin web is very sensitive to elevated temperatures and charring. Additionally, adhesives used in finger joints in the flanges and the joint between the flanges and the web influences the load-bearing capacity. The loss of strength and stiffness were seen in wood at elevated temperatures is considered in the ECSM by a zero-strength layer. The zero-strength layer (ZSL) is an additional reduction of the cross-section to compensate for the decrease in strength and stiffness properties. The development of the expressions to calculate the ZSL depths for compression elements is discussed in this paper.
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| 45. |
- Mäger, K. N., et al.
(författare)
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Influence of adhesives on fire resistance of wooden i-joists
- 2021
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Ingår i: World Conference on Timber Engineering 2021, WCTE 2021. - : World Conference on Timber Engineering (WCTE).
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Konferensbidrag (refereegranskat)abstract
- FIRENWOOD is an Era-NET cofund Forest Value project (2019-2022) dealing with the fire resistance testing and design methods of engineered wood products at elevated temperatures and fire. As one part of the project, various adhesives, allowed for load bearing timber structures, are tested in finger joints in small scale and medium scale fire tests. The paper will provide a description of these tests and an overview and analysis of the results. Based on the test data of both types, a good agreement regarding the adhesive performance between the tests can be shown. The design model for wooden I-joists is described and values for the depth of the zero-strength layer are proposed for different adhesive performance levels in finger joints.
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| 46. |
- Mäger, Katrin Nele, et al.
(författare)
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Procedure for implementing new materials to the component additive method
- 2019
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Ingår i: Fire safety journal. - : Elsevier BV. - 0379-7112 .- 1873-7226. ; 107, s. 149-160
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Tidskriftsartikel (refereegranskat)abstract
- The performance of light timber frame wall and floor assemblies in fire depends on their composition. The assemblies' ability to form fire-separations between building compartments (separating function) can be assessed by full-scale fire testing or calculation methods. Calculations are the low cost and more flexible alternative.The component additive method is a commonly used calculation method for fire design of timber structures. The method considers the insulation ability of the material layers present in the assembly. The component additive method described in this article is developed to be flexible to implement different materials and products of different dimensions. However, the amount of different materials currently included in this method is rather limited and there is no generally accepted procedure to implement new materials.This paper presents a common agreement of the procedure to implement new materials which comprises of: (1) the design and execution of model-scale fire tests; (2) determination of the modified thermal properties needed for simulations; (3) thermal simulations of assemblies in fire conditions; (4) development of design equations and; (5) verification by one or more full-scale fire test(s). The abovementioned steps have been clearly presented in this paper and supported by examples.
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| 47. |
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| 48. |
- Nele Mäger, Katrin, et al.
(författare)
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Development of Design Equations for the Component Additive Method for Paroc eXtra
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report details the development of effective thermal properties and design equations for Paroc eXtra which can be used for the improved component additive method for fire design of timber structures. The results are validated with full scale fire tests where such reports are available.
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| 49. |
- Nore, Kristine, et al.
(författare)
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Execution of timber structures
- 2014
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Ingår i: INTER : International Network on Timber Engineering Research : Proceeding. - : Timber Scientific Publishing.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 50. |
- Olofsson, Robert, et al.
(författare)
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Large-scale fire tests of engineered wood systems
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report presents the four large-scale fire tests performed within the FIRENWOOD project. The aim of the tests was to verify the improved fire design models for the I-joists and crosslaminated timber. The results of the loaded floor test with cross-laminated timber were also compared with results from an unloaded model-scale test with similar lamella thicknesses and adhesive. The aim of the compartment fire test was to study the behaviour of I-joists in physically based fire compared to the behaviour in standard fire. The second aim was to compare the fire behaviour of the compartment made of timber frame assemblies with I-joists and the previously performed similar compartments made with CLT. All large-scale tests reported here were performed with engineered wood structures using adhesive No.9
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