Modelling charring of timber exposed to natural fire

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

Charring of timber structural elements in fire is one of the most fundamental phenomena that affect the fire resistance of these elements. For an accurate and safe design of structural fire resistance, it is important to consider charring of timber in natural fire exposures, since determining charring for standard fire exposure, which is a common practice, is outdated and in some cases unsafe, due to the fact that some natural fires can be much more severe. Currently, the prescriptive approach and simplified design methods fail to give information about charring of timber elements exposed to natural fire and thus, a performance based design is needed. Therefore, this paper presents an upgrade and extension of a recently developed heat-mass-pyrolysis model named PYCIF. Originally, PYCIF model was developed only for standard fire conditions. In the present paper, several studies and analyses are performed to extend model application to natural fire conditio ns. Firstly, the sensitivity study is performed, where the impact of model parameters on the charring development is investigated. It is discovered, that the kinetic parameters for the reaction rate of the active cellulose production, namely activation energy E1 and pre-exponential factor A1, are the most influential. In the next analyses the model calibration for small scale cone calorimeter tests and large scale natural fire tests of cross-laminated timber (CLT) floor system is performed. A robust nature of the model is identified since minor parameter calibration is required for an accurate prediction of the charring depth and temperatures in timber elements exposed to various fire conditions. Furthermore, a strong connection between the heating rate of fire and kinetic parameters is discovered. In cases of faster heating rate, the kinetic parameters govern slower reaction rate of active cellulose.

• Language: English
• Keywords: civil engineering, heat-mass-pyrolysis model, PYCIF, charring, natural fire, sensitivity analysis
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Year: 2023
• Number of pages: Str. 1-14
• Numbering: Vol. 69, iss. 19
• PID: 20.500.12556/RUL-146448
• UDC: 691
• ISSN on article: 1611-4663
• DOI: 10.1186/s10086-023-02091-4
• COBISS.SI-ID: 151064323
• Publication date in RUL: 02.06.2023

Record is a part of a journal

• Title: Journal of wood science
• Shortened title: J. wood sci.
• Publisher: Springer.
• ISSN: 1611-4663
• COBISS.SI-ID: 512614937

Secondary language

• Language: Slovenian
• Title: Modeliranje oglenenja lesa izpostavljenega naravnemu požaru
• Keywords: gradbeništvo, toplotno-vlažnostno-pirolizni model, PYCIF, oglenenje, naravni požar, analiza občutljivosti

Projects

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