Paper DOI
10.2495/SAFE090421
Transaction
Volume
108
Pages
9
Published
2009
Size
924 kb
Author(s)
E. M. M. Fonseca & L. M. S. Barreira
Abstract
Wood material is being used increasingly for structural engineering applications in buildings and other special engineering productions. To assess safety rules, this type of element should have sufficient mechanical resistance to guarantee the design loads. Wood is a natural material and is subject to many constantly changing influences. High wood vulnerability, due to accidental conditions, requires rigorous thermal and mechanical assessment. The combustion and the chemical phenomena occurring in the wood during an accidental situation of elevated temperature is a complex study issue. When wood structures are exposed to high temperatures, the burned wood becomes a char layer, which loses all strength, but the insulating temperature rises in the core of the material. The charring rate is more or less constant and mainly depends on the density and moisture content of the wood. Safety rules and guidelines should be useful for different wood applications. The fire safety of this type of material involves prevention, inhibition, detection and evacuation. This involves appropriate design rules, installation, construction and maintenance of the wood material applications. This paper proposes an experimental and a numerical method for charring rate determination in pine wood. Different pine sections will be tested and submitted to high temperatures using a heating power unit based on electrical resistances. The temperature results will be measured through a wood profile during time heating exposure. Using appropriated material properties and boundary conditions, reasonable predictions of the charring layer with a finite element analysis method can be provided. The thermal response obtained with the finite element formulation will be compared with experimental results in several series of wood pine profiles. The char layer thickness will be determined. Keywords: charring rate, wood, high temperatures, safety.
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http://www.witpress.com/elibrary/wit-transactions-on-the-built-environment/108/20334
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