Technical note - Thermal exposure of wood in standard fire resistance tests

Schmid, Joachim; Brandon, Daniël; Werther, Norman; Klippel, Michael

doi:10.1016/j.firesaf.2018.02.002

Cited by 26 publications

(26 citation statements)

References 8 publications

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“…For each design fire furnace curve, three tests were run with wood specimens in the lid as well as one test with a noncombustible lid. Currently, there are discussions regarding the amount of fuel used when comparing combustible and noncombustible construction materials . The fuel required will vary based on furnace configuration, so to evaluate the difference in fuel consumption between the two lid types on, the gas flow was measured for all tests.…”

Section: Resultsmentioning

confidence: 99%

“…The argument being that the fuel input into a furnace differs between building materials when controlled based on temperature, and, therefore, the current fire‐resistance ratings from a furnace test do not account for the contribution of a combustible structure to the intensity and duration of a real fire. Despite these concerns, Schmid et al point out that, regardless of the lid construction (noncombustible vs wood inserts), the thermal exposure is equivalent in furnaces simulating a ventilation controlled fire development for a pre‐defined duration …”

Section: Discussionmentioning

confidence: 99%

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Simulating real compartment fire conditions in a furnace

et al. 2019

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Summary In the United States, wood has been traditionally used in residential construction. However, the combustibility of wood still limits its use as a building material in prescriptive building codes, and to overcome the limitations, performance‐based codes can be used. In order to properly analyze performance‐based designs, more information on the fire performance of materials is required, including fire performance under different fire exposures. The char rate when timber elements are exposed to the standard time‐temperature curve have been well characterized and can be used to determine the fire‐resistance rating. However, much less is known about the rate of char formation under other fire exposures and time‐temperature curves. In this study, we used time‐temperature data from full‐scale compartment fire tests and applied that data in an intermediate‐scale horizontal furnace. By measuring the furnace temperature, fuel consumption, and heat flux during the various tests, we identified that the furnace could closely replicate the shape of a real time‐temperature fire curve from a ventilation controlled compartment. However, the furnace fell short in terms of meeting the peak temperatures at flashover and heat fluxes expected in a real compartment fire.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Simulating real compartment fire conditions in a furnace

et al. 2019

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“…If the specimen consists of combustible material, it may burn inside of the furnace (Figure ), providing a secondary source of heat release. This effect was measured in technical note, where approximately 25% to 32% of the heat produced in the furnace test of solid wood panels was attributed to the combustion of a wooden specimen.…”

Section: The Energy Balance In the Furnacementioning

confidence: 97%

The discrepancies in energy balance in furnace testing, a bug or a feature?

2019

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Summary The paper aims to explain the differences found in the heat release rate measurements in a large sample of standard fire tests (EN 1363‐1). A total of 379 tests of vertical assemblies was investigated, all performed in furnace SPARK of the ITB Fire Testing Laboratory, in 2015‐2018. The assemblies were subdivided into two groups—wall assemblies and fire‐rated doors. These assemblies were also compared with the results of the test of a wall built with aerated autoclaved concrete blocks that was considered as the benchmark test. It was observed that walls built with highly insulated sandwich panels require less heat to maintain standard thermal exposure conditions (20%‐30% less) than their counterparts built from gypsum plasterboard or aluminium and fire‐rated glass. In case of doors, it was observed that combustible samples required significantly less heat than the benchmark case (40%‐70% less), which indicates that the combustion of the sample inside of the furnace was an additional, significant source of heat release, that may skew the qualitative assessment of their performance in fire. A more in‐depth discussion of the results is provided, with some ideas on the direction of further developments in fire testing.

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“…In terms of heat fluxes, for the configurations and materials tested herein, the plate thermometer temperature is the same for both concrete and CLT tests, which is not at all surprising given that this is what controls the furnace. Therefore, the net total heat flux to the samples can be said to be similar the absorbed heat flux by the sample is around 3.5 times greater for concrete than for timber.…”

Section: Energy Analysesmentioning

confidence: 99%

Comparative energy analysis from fire resistance tests on combustible versus noncombustible slabs

Bartlett

McNamee²,

Robert

et al. 2019

Fire and Materials

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Summary Standard fire resistance tests have been used in the design of structural building elements for more than a century. Originally developed to provide comparative measures of the level of fire safety of noncombustible products and elements, the recent resurgence in engineered timber construction raises important questions regarding the suitability of standard fire resistance tests for combustible structural elements. Three standard fire resistance floor tests (5.9 m × 3.9 m in plan), one on a concrete slab and two on cross‐laminated timber (CLT) slabs, were undertaken to explore some of the relevant issues. The fuel consumption rate within the furnace was recorded during these tests, and the energy supplied from this was determined. An external fuel supply (from natural gas supplied to the furnace) equating to approximately 3 MW was recorded throughout the concrete test, whereas this was about 1.25 MW throughout the CLT tests. The total heat release rate was calculated using carbon dioxide generation calorimetry; this yielded values of approximately 1.75 MW during the CLT tests (ie, an additional energy contribution of approximately 0.5 MW from the timber). This demonstrates that considerably more energy input (by about 1.25 MW) was needed to heat the system when the test sample was noncombustible. A further series of six large‐scale compartment fire experiments (6 m × 4 m × 2.52 m) was undertaken to further explore comparative performance of combustible versus noncombustible construction when the external fuel load is kept constant and is governed by more realistic compartment fire dynamics. For a fuel‐controlled case, the peak temperatures in the compartment with an unprotected CLT ceiling were approximately 200°C higher than in the compartments with a concrete ceiling, whereas for a ventilation‐controlled case, the compartment with a CLT slab ceiling displayed a burning duration that increased by approximately 15 minutes. Potential implications for standard fire resistance testing of combustible specimens are discussed.

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Technical note - Thermal exposure of wood in standard fire resistance tests

Cited by 26 publications

References 8 publications

Simulating real compartment fire conditions in a furnace

Simulating real compartment fire conditions in a furnace

The discrepancies in energy balance in furnace testing, a bug or a feature?

Comparative energy analysis from fire resistance tests on combustible versus noncombustible slabs

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