Thickness of zero-strength layer in timber beam exposed to fuel-controlled parametric fires

Huč, Sabina (author), Hozjan, Tomaž (author), Pečenko, Robert (author)

Fire resistance is one of the essential requirements to be fulfilled in the design of timber structures. For this purpose, a reduced cross-section method is given in the European standards, Eurocodes. The method is based on the assumption that an initial, rectangular timber cross-section exposed to fire conditions reduces to an effective cross-section, which has material properties as at a room temperature. The reduced part of the cross-section with no resistance is determined by a sum of two parameters, namely a charring depth and a thickness of zero-strength layer. Eurocodes give a value of the latter only for the standard fire exposure, which is only one of the fire curves proposed in the same standards. Therefore, the present paper examines the thickness of zero-strength layer in case of 46 different fuel-controlled parametric fire exposures applied to a timber beam from three sides. A four-phase numerical analysis is applied for this purpose that includes the use of a hygro-thermal model and a mechanical model to determine temperatures of timber over the cross-section and the mechanical resistance of timber beam in fire conditions, respectively. The results show that the thickness of zero-strength layer takes the values between 7.9 and 18.4 mm for the fuel-controlled parametric fire exposures. Since it is clearly dependent on the parameters describing the parametric fire curve, five equations are proposed that can be used for determination of the thickness of zero-strength layer in case of parametric fire exposures.

• Language: English
• Keywords: zero-strength layer, parametric fire, timber beam
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FGG - Faculty of Civil and Geodetic Engineering; FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: Str. 929-944
• Numbering: Vol. 57, iss. 4
• PID: 20.500.12556/RUL-151732
• UDC: 624.011.1:624.072.2:614.84
• ISSN on article: 0043-7719
• DOI: 10.1007/s00226-023-01480-8
• COBISS.SI-ID: 160140291
• Publication date in RUL: 18.10.2023

Record is a part of a journal

• Title: Wood science and technology
• Shortened title: Wood sci. technol.
• Publisher: Springer Nature, International Academy of Wood Science
• ISSN: 0043-7719
• COBISS.SI-ID: 9151749

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: debelina nenosilnega sloja, parametrični požar, leseni nosilec

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: N2-0183
• Name: Stohastični model oglenenja lesa v pogojih naravnega požara

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0260
• Name: Mehanika konstrukcij