engleski

Thermal behavior of polymer foam cavity insulated LSF walls under standard fire conditions

In some parts of the world, lightweight steel framed (LSF) construction systems have proven to be a fast, economical, and efficient method of constructing residential and non-residential buildings, offering significant advantages over concrete and masonry structures. Since thin steel lipped channel studs have high thermal conductivity, thermal insulation should be optimized to ensure the lowest possible thermal transmittance for an energy efficient building. In current practice, mineral wool (MW) placed in the cavity between at least two layers of gypsum plasterboard (GB) is the preferred choice of insulation. However, such LSF systems using MW do not take into account deficiencies such as the thermal bridging effect and potential moisture condensation, which can reduce the thermal performance of the assembly. It is known that polymer insulation materials have better thermal conductivity and resistance to water permeability than MW. Consequently, they can provide better thermal performance at ambient temperature for the same overall thickness of the assembly. However, the use of polymer insulation materials in LSF structures has not been explored due to the flammability of the material, which can negatively affect their fire resistance. Therefore, a new LSF composite structure is being studied in which steel studs and polymer foam are encapsulated in gypsum fiberboard (GFB). GFBs are believed to provide better fire performance than standard GFBs. Spacers are also used to separate the steel and lining boards to prevent thermal bridging. This paper presents the results of a fire test on such a LSF composite assembly and details of the preliminary finite element model developed to simulate the heat transfer mechanism through the specimen. The numerical analyzes were performed using the ABAQUS finite element program. The model is based on the preliminary thermal properties of the polymer foam and gypsum fiberboards tested by TGA and DSC methods, as well as data from the literature. The fire test showed that while the GFBs maintained their integrity the PUR foam did not ignite, and no significant temperature increases were observed at the steel structure or at the ambient side of panel. Numerical models showed good correlation with the fire test until ignition of the PUR foam.

LSF panels ; Fire resistance ; Fire testing, Thermal properties

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