| 1. |
- Gernay, Thomas, et al.
(författare)
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Experimental investigation of structural failure during the cooling phase of a fire : Timber columns
- 2023
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Ingår i: Fire and Materials. - : John Wiley and Sons Ltd. - 0308-0501 .- 1099-1018. ; 47:4, s. 445-
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes fire tests on loaded glued laminated timber columns in which the structural response was measured during the heating and cooling phases. Identical columns with 280 × 280 mm2 cross-section and 3.7 m length were tested under various heating durations in a standard furnace to investigate integrity to full burnout. Two of the columns were subjected to ISO 834 heating until failure and their measured fire resistance was 55 and 58 min, respectively. Two columns were subjected to 15 min of ISO 834 heating followed by controlled cooling; these columns failed during the cooling phase, respectively after 98 and 153 min. Flame self-extinction occurred after approximately 40 min while smoldering continued locally. Two columns tested under 10 min of ISO 834 heating both survived the defined heating–cooling exposure. Thermocouples inside the columns show sustained temperature increases for hours after the end of the heating phase. These full-scale furnace experiments show that timber columns may fail during the cooling phase after exposure to standard heating for about 25% of the standard fire resistance duration. These results, in line with previous numerical predictions, highlight the need for further investigation into fire safety until full burnout for timber structures.
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| 2. |
- Gernay, Thomas, et al.
(författare)
-
Experimental investigation of structural failure during the cooling phase of a fire : Concrete columns
- 2022
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Ingår i: Fire safety journal. - : Elsevier Ltd. - 0379-7112 .- 1873-7226. ; 134
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Tidskriftsartikel (refereegranskat)abstract
- Structures may collapse during the cooling phase of a fire, yet standard furnace tests only measure the response under heating. There lacks experimental test protocols and design methods to assess resistance until burnout. This paper describes a new experimental approach for burnout resistance evaluation, reports experimental data on loaded reinforced concrete columns in furnace tests with cooling down phases, and presents numerical models of the tests. The test results show that columns designed for a standard fire resistance of 60 min exhibited a fire resistance of 83 min in the furnace but failed during the cooling phase when the burners were shut off after 72 min while the load was maintained. Two other specimens survived exposure to heating of 45 and 55 min, respectively, and their residual capacity was measured. Finite element analyses show agreement with the tests, showing applicability of numerical methods for evaluating burnout resistance of concrete columns. These findings demonstrate experimentally that delayed thermal-mechanical effects can jeopardize structural stability in real fires, and provide a framework to measure these effects. Moving beyond fire resistance to quantify the response until burnout will support designs for safety of occupants and firefighters throughout the fire and promote repairability and resilience.
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| 3. |
- Mohaine, Siyimane, et al.
(författare)
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Cross-comparison of screening tests for fire spalling of concrete
- 2021
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Ingår i: Fire and Materials. - : John Wiley and Sons Ltd. - 0308-0501 .- 1099-1018. ; 45:7, s. 929-
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Tidskriftsartikel (refereegranskat)abstract
- Concrete spalling is an important phenomenon to consider when evaluating the fire behavior of concrete, as this can sometimes have an impact on the structural capacity of the studied element. Spalling can be assessed experimentally using screening tests although it is influenced by the size, geometry, and boundary conditions of the tested element, among other factors. No standardized and systematic methods are yet available to assess concrete spalling sensitivity by testing. Plus, comparative results between screenings tests (small and medium scale) and full-scale tests to evaluate their representativity remain scarce in the literature. In this study, five different spalling tests—with different geometries and boundary conditions—that are used as screening tests were investigated. A concrete mix known to be sensitive to spalling was used to evaluate the representativity of two types of screening tests (material screening tests and intermediate-scale screening tests). The representativity of these test setups was evaluated by comparing the measured spalling depths to the spalling measured on a full-scale slab test using the same concrete mix. This comparative study confirmed that the presence of load and/or restraint was essential for a good representativity for a screening test but should always be implemented in large enough specimens.
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| 4. |
- Mohaine, Siyimane, et al.
(författare)
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PERFORMANCE OF PASSIVE PROTECTION OF CROSS LAMINATED TIMBER DURING STANDARD FURNACE TESTS AND NATURAL FIRES
- 2023
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Ingår i: 13th World Conference on Timber Engineering, WCTE 2023. - 9781713873297 ; 3, s. 1839-1847
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Konferensbidrag (refereegranskat)abstract
- This paper presents the results of an experimental campaign designed to compare and understand the performance of passive protection under exposure to standard furnace tests and natural fires. As part of this campaign, five natural fire experiments were performed with partially protected cross-laminated timber (CLT) compartments under a range of ventilation conditions. In all the tests, only one side wall was left completely unprotected, and all other timber surfaces were protected with either two layers of 18 mm standard gypsum boards (GB) or two layers of 25 mm standard GBs. The structural CLT ceilings were subjected to a superimposed dead load of 1.35 kN/m² during the natural fire tests, and the fire load was (on average) 950 MJ/m²; chosen to represent the Eurocode 1991-1-2 characteristic value for dwellings. The performance of the passive protection was mainly evaluated with regards to the time to reach a protected timber surface temperature of 250°C. The testing confirms that the resulting fire protection performance of a given gypsum board layout depends on the ventilation conditions of the fire compartment, with more severe (and closest to ISO testing) outcomes when testing under ventilation-controlled scenarios. This paper provides data that sheds light on the co-dependency of the passive protection design and compartment fire dynamics and underlines the importance of considering the safety objectives of a building when defining the performance criteria of its structural elements.
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| 5. |
- Pimienta, Pierre, et al.
(författare)
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Recommendation of RILEM TC 256-SPF on fire spalling assessment during standardised fire resistance tests : complementary guidance and requirements
- 2024
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Ingår i: Materials and Structures/Materiaux et Constructions. - : Springer Science and Business Media B.V.. - 1359-5997 .- 1871-6873. ; 57:1
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Tidskriftsartikel (refereegranskat)abstract
- The recommendation is based on the co-authors’ work organized by the RILEM TC 256-SPF “Spalling of concrete due to fire: testing and modelling”. It aims to provide useful information, guidance and best practices in fire spalling assessment to laboratories that perform large-scale tests based on fire resistance test standards. It provides guidance on the spalling observation techniques during testing, as well as post-test spalling quantification/assessment methods. This document is intended to be used in conjunction with the fire resistance test standards, e.g. EN 1363-1 and ISO 834-1.
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| 6. |
- Pimienta, Pierre, et al.
(författare)
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Recommendation of RILEM TC 256-SPF on the method of testing concrete spalling due to fire : material screening test
- 2023
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Ingår i: Materials and Structures/Materiaux et Constructions. - : Springer Science and Business Media B.V.. - 1359-5997 .- 1871-6873. ; 56:9
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Tidskriftsartikel (refereegranskat)abstract
- The recommendation is based on the co-authors’ work organized by the RILEM TC 256-SPF “Spalling of concrete due to fire: testing and modelling”. The Committee has defined two types of screening tests for characterization of concrete propensity to fire spalling: Material screening tests and Product screening tests. Definitions of both types of tests are given in the paper. The following recommendations apply to Material screening tests. The material screening tests described in these recommendations are a set of minimum requirements to test concrete spalling propensity (for example, the minimal specimen size). This document covers the aspects of concrete characterization, specimen geometries, storage conditions, test methods and measured parameters.
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