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KL-trä är ett relativt nytt konstruktionsmaterial som lämpar sig som stomme i bostadshus, offentliga och industriella byggnader. Eurokod 5 är den europeiska standarden för dimensionering av träkonstruktioner som är obligatorisk att använda i alla länder. Den omfattar både dimensionering i normalfallet och branddimensionering. Nuvarande version för branddimensionering EN 1995-1-2:2004 publicerades 2004 [1]. Den saknar regler för dimensionering av KL-trä. En ny version av Eurokod 5 beräknas komma 2025, den finns idag som utkastet prEN 1995-1-2:2025 [2]. De två versionerna av Eurokod 5 jämförs för KL-trä i denna artikel. Artikeln baseras på ett examensarbete vid Linnéuniversitetet [3]. Endast konstruktioner med synlig träyta har analyserats.

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.

This chapter deals with the fire properties and performance of wood products and structures. It starts with two subchapters on the basic physical and chemical properties under fire conditions including fire-retardant treatments to obtain higher reaction to fire classes. A new European standard to evaluate their long-term fire performance is included. The third subchapter gives an overview of the fire safety design of wood products in buildings. The European system for fire safety of construction products is explained with the two main fire scenarios to be considered: the initial fire where visible wood surfaces may contribute, and the fully developed fire, which is important to limit the fire to the room of origin. Generally speaking, wooden structures can obtain high fire resistance, whereas the surface properties in the initial fire are less favorable. The European reaction to fire class D is fulfilled for most wood products. North American systems are different and their classification of wood products is described briefly. Methods for calculating the fire resistance of wood elements according to Eurocode 5, and US systems, structural detailing, and fire safety at building sites are presented. The chapter ends by explaining the possibilities for using performance-based fire safety design and active fire protection by, for example, sprinklers.

This book provides guidance on the design of timber buildings for fire safety, developed within the global network Fire Safe Use of Wood (FSUW) and with reference to Eurocode 5 and other international codes. It introduces the behaviour of fires in timber buildings and describes strategies for providing safety if unwanted fires occur. It provides guidance on building design to prevent any fires from spreading while maintaining the load-bearing capacity of structural timber elements, connections and compartmentation. Also included is information on the reaction-to-fire of wood products according to different classification systems, as well as active measures of fire protection, and quality of workmanship and inspection as means of fulfilling fire safety objectives. Presents global guidance on fire safety in timber buildings Provides a wide perspective, covering the whole field of fire safety design Uses the latest scientific knowledge, based on recent analytical and experimental research results Gives practical examples illustrating the importance of good detailing in building design Fire Safe Use of Wood in Buildings is ideal for all involved in the fire safety of buildings, including architects, engineers, firefighters, educators, regulatory authorities, insurance companies and professionals in the building industry.

The possibilities for building in wood have gradually increased in recent decades mainly due to environmental benefits. But there are still restrictions in terms of fire regulations in many countries, especially for taller buildings. The situation has therefore been mapped in about 40 countries on four continents as an update to a survey in 2002. The main issues are how high buildings with load-bearing wooden frames may be built and how much visible wood may be used both inside and outside on facades. The restrictions apply primarily to prescriptive fire design according to simplified design with detailed rules, which are mainly used for residential buildings and offices. For more complicated constructions e.g. public buildings, shopping centers, arenas and assembly halls, performance based design can be used by fire safety engineering design using, e.g. methods for evacuation and smoke filling, which increases the possibilities of using wood in buildings. The possibilities to use wood in buildings increase if sprinklers are installed, which is highlighted. Major differences between countries have been identified, both in terms of the number of storeys permitted in wood structures, and of the amounts of visible wood surfaces in interior and exterior applications. Several countries have no specific regulations, or do not limit the number of storeys in wooden buildings. The conclusion is that the differences are still large and that many countries have not yet started to use larger wood constructions despite supplies of forest resources, but harmonizing activities on performance based principles are ongoing worldwide.

En internationell handbok om brandsäker användning av träprodukter och träkonstruktioner Fire Safe Use of Wood in Buildings publicerades 2022. Den inkluderar de senaste vetenskapliga rönen på global nivå för praktiska byggtillämpningar. Handboken omfattar utökad användning av konstruktionsstandarder med praktisk vägledning samt principer och exempel på funktionsbaserad brandteknisk dimensionering.

Wood and wood-based products are extensively used in the building sector due to their interesting combination of properties. Fire safety and fire spread, however, are of utmost concern for the protection of buildings. Therefore, in timber structures, wood must be treated with fire-retardant materials in order to improve its reaction to fire. This article highlights the flame retardancy of novel hybrid organic–inorganic halogen-free coatings applied on plywood substrates. For this purpose, either a huntite-rich mineral (H5) or its modified nano-Mg (OH)2 type form (H5-m), acting as an inorganic (nano) filler, was functionalized with reactive oligomers (ROs) and incorporated into a waterborne polymeric matrix. A water-soluble polymer (P (SSNa-co-GMAx)), combining its hydrophilic nature with functional epoxide groups, was used as the reactive oligomer in order to enhance the compatibility between the filler and the matrix. Among various coating compositions, the system composed of 13% polymeric matrix, 73% H5 and 14% ROs, which provided the best coating quality and flame retardancy, was selected for the coating of plywood on a larger scale in one or two layers. The results indicated that the novel plywood coating systems with the addition of ecological coating formulations (WF-13, WF-14 and WF-15), prepared at two layers, reached Euroclass B according to EN13501-1, which is the best possible for fire systems applied to wood. © 2022 by the authors.

This chapter covers control of workmanship, fire safety during construction, responsibilities and enforcement, fire detection and suppression and emergency procedures. Quality and inspection of workmanship are vital for high-quality buildings, whether of timber or other construction materials. Timber buildings require certain precautions due to the risk for greater exposure of combustible materials. Furthermore, not all fire safety measures for the final building will be in place throughout construction; consequently, adequate processes are required to maintain the fire safety of building sites. All construction sites require formalised fire safety management systems, including auditing of contractors and subcontractors.

This chapter summarises the regulatory control systems for fire safety design of buildings in different regions around the globe. It is focused on the possibilities to use wood products and timber structures according to prescriptive requirements. The possible use of structural timber elements and visible wood surfaces in interior and exterior applications are reviewed and presented in tables and maps. They apply mainly to residential and office buildings. Performance-based requirements may be used in several countries and can be used to verify further applications of wood.

This chapter presents the reaction to fire performance of wood products used in buildings as internal surface finishes, exterior wall claddings and roof coverings. It describes the systems used in compliance with prescriptive regulations in different regions, and it also covers the characteristics of wood products for performance-based design, and methods for improving the reaction to fire performance of wood products.

A wide variety of active fire protection systems are available to fire safety practitioners. In addition to passive fire protection measures, some level of active fire protection is normally required to meet the expected minimum level of fire safety in modern buildings. Active fire protection can also be used to increase the fire safety in order to achieve a more flexible fire safety design and an acceptable level of fire safety in buildings. There are many types of active fire protection systems, but this chapter deals mainly with automatic fire sprinkler systems, since they are often used to facilitate the use of timber as structure, internal linings and external facades in large or complex buildings. Sprinklers are required in some countries for taller timber buildings, as described in Chapter 4.

This chapter describes means of preventing spread of fire and smoke between compartments in timber buildings. Much of this applies to all buildings independent of materials used, but some topics are especially relevant for timber buildings. This chapter highlights critical paths of possible spread of fire into, within and through timber structures, including solutions and detailing to prevent uncontrolled spread of fire and smoke.

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.

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.

The new classification system for the reaction to fire performance of building products in Europe, the so-called Euroclass system, has been applied to five different types of wood products: wood-based panels, structural timber, glued laminated timber, solid wood paneling and cladding, and wood flooring as being products with known and stable fire performance. Most wood products fall in classes D-s2, d0 or Dfl-s1 (for floorings). Some products may also fall in the main classes C or E. Testing has been performed according to EN 13823 SBI Single Burning Item test, EN ISO 9239-1 Radiant panel test, and EN ISO 11925-2 Small flame test. More than 100 wood products in different end use applications have been studied. With the experimental evidence, clear relationships between the main Euroclass fire performance parameters and product parameters (such as density and thickness) have been demonstrated. The new European system for the reaction to fire performance classes consists of two sub-systems, one for construction products, i.e., mainly wall and ceiling surface linings, and another similar system for floorings. The main parameters influencing the reaction to the fire-retardant characteristics of all wood products are product thickness, density and end-use conditions, such as substrates or air gaps behind the product.

Tre sprinklersystem, traditionell vattensprinkler, boendesprinkler och dimsprinkler (high pressure water mist), har jämförts och applicerats i ett bostadshus med 22 våningsplan. Arbetet ger en bild av systemens effektivitet vad gäller vattenåtgång och fysisk påverkan på byggnaden. Ett optimalt system har låg vattenåtgång och hög utnyttjandegrad vilket innebär att systemet täcker en stor yta per munstycke. Dessa aspekter bidrar till minskad risk för vattenskador på byggnaden. För att kunna bestämma vattenåtgång samt göra en rättvis jämförelse har systemen anpassats till samma verkningsytor och beräknats på samma sätt.

Bidrag till encyklopedi

Ej belagd 200417