Timber under real fire conditions – the influence of oxygen content and gas velocity on the charring behavior

Schmid, Joachim; Santomaso, Alessandro; Brandon, Daniël; Wickström, Ulf; Frangi, Andréa

doi:10.1108/jsfe-01-2017-0013

Cited by 15 publications

(15 citation statements)

References 5 publications

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“…As the timber is completely turned into char at approximately 300°C, the predicted temperature profile in the timber throughout the duration of the fire can be used to estimate the charring rate. Schmid et al (2016) showed that there is a practically constant ratio between charring rate and heat release rate. This ratio is used to determine the heat release rate of CLT from the calculated charring rates.…”

Section: Postflash Design Fires For Compartments With Exposed Timbermentioning

confidence: 99%

Fire Design of CLT in Europe

Östman¹,

Schmid²,

Klippel³

et al. 2018

WFS

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The fire safety design of cross-laminated timber (CLT or X-Lam) in Europe is governed by the Construction Products Regulation and its essential requirements, as for all other building products. These requirements are mandatory, to be used in all European countries. They include classification systems for reaction to fire of building products, fire resistance of building elements, and structural Eurocodes. The reaction-to-fire performance of CLT in accordance with the European classification system is specified. Higher classes can be reached by chemical treatments, but the durability of the reaction-to-fire performance needs to be fulfilled according to a new European system. The fire resistance design of CLT building elements is not included in Eurocode 5, the structural Eurocode for timber, but can be either tested according to European standards or calculated by using design methods being developed recently. This article provides information about both reaction to fire and fire resistance of CLT in Europe.

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Section: Postflash Design Fires For Compartments With Exposed Timbermentioning

confidence: 99%

Fire Design of CLT in Europe

Östman¹,

Schmid²,

Klippel³

et al. 2018

WFS

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“…Bei ausreichend großer Brennstoffmenge, i. d. R. Mobiliar, stellt sich in diesen Bränden im Raum ein sehr niedriger Sauerstoffgehalt ein. Dies ist ein Grund, warum es für Brandversuche jeder Art und insbesondere für brennbare Bauteile wie Brettsperrholz notwendig ist, den Sauerstoffgehalt zu dokumentieren, um die richtigen Schlussfolgerungen ziehen zu können .…”

Section: Brandprüfungenunclassified

Brandeinwirkung auf Holzbauteile im Prüfofen und bei realen Bränden

et al. 2018

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Brandschutzexperten diskutieren derzeit die Gültigkeit von Brandprüfungen für Holzbauteile. Im Raum steht einerseits die allgemeine Aussage, dass brennbare Bauteile in Prüfungen einer von nicht brennbaren Bauteilen abweichenden thermischen Einwirkung ausgesetzt werden. Andererseits wird darauf hingewiesen, dass die sichere Verwendung von flächigen Holzbauteilen (Massivholzbauteile), z. B. Brettsperrholz, durch Normbrandprüfungen nicht geprüft werden kann, da diese Bauteile die Brandlast erhöhen und somit keine Aussagen im traditionellen Rahmenwerk des Feuerwiderstands getätigt werden können. Der vorliegende Beitrag zeigt Übereinstimmungen und Unterschiede zwischen nicht brennbaren und brennbaren Bauteilen in Normbrandprüfungen auf. Es wird gezeigt, dass die thermische Einwirkung für nicht brennbare und brennbare Bauteile in Normbrandprüfungen gleichwertig ist, auch wenn es sich um – wie im Falle von Brettsperrholz – großflächige Bauteile handelt. Die durch brennbare Bauteile zusätzlich im Brandraum verbrennende Brandlast kann durch Normbrandprüfungen nicht direkt ermittelt werden. Hierfür müssen, falls notwendig, andere Methoden verwendet werden, die zum Teil erst in der Entwicklung stehen. Die durch brennbare raumbildende Tragstrukturen zusätzliche Brandlast führt nicht zu höheren Temperaturen im Brandraum, sondern zu einer veränderten Brandeinwirkung an der Fassade. Diesem Umstand wird im Moment in Bauordnungen durch verschiedene Regeln Rechnung getragen.

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“…Brandon [4] based his concept on a comparison of the heat release rate (HRR) measured in a large series of compartment experiments. The basis of the comparison by Brandon [4] was the HRR of cone calorimeter tests with timber specimens, where also the charring rate was measured [9,10]. Comparing the measured HRR and the charring rates observed in the compartment experiments, a significant difference between the estimated and the measured HRR was observed.…”

Section: Introductionmentioning

confidence: 99%

“…Following Wade's methodology, a parameter study would be required between the bounds while Brandon's approach is stated to be conservative for the evaluated compartment experiments. Yet, as the significant reduction of the structural fuel was not apparent, the approach using a fitting factor was further studied by Schmid et al [10]. Schmid et al analysed the char layer with respect to its yield profile and the corresponding heat content.…”

Section: Introductionmentioning

confidence: 99%

Structural Timber In Compartment Fires – The Timber Charring and Heat Storage Model

Schmid

Frangi

2021

Open Engineering

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The influence of exposed timber surfaces on compartment fires has been well documented in various studies in recent decades. Yet available design concepts still typically neglect the influence of an additional fire load from linear structural timber elements such as beams and columns. As rules for large shares of exposed timber surfaces, e.g. by panels, are rare, authorities and fire safety engineers demand often mock-up compartment fire experiments to estimate the fire safety of a particular design. Such experiments, however, are costly, time consuming, and give limited insights into the potential fire scenarios and may fail to represent properly the fundamental effects arising from exposed structural timber elements in a fire. An approach to overcome these existing limitations is presented, which is able to estimate the contributions from structural timber to a fire from its fully developed- and decay phase until burnout. The model input is developed from an experimental campaign where the relevant effects of fire exposed structural timber could be isolated and measured. It was found that the energy stored in the char layer is a key characteristic for describing the fire dynamics of compartment fires with exposed structural timber. Consequently, the proposed approach describes a framework for the Timber Charring and Heat storage, the TiCHS-model. The validation of the model is shown in this paper by means of existing compartment experiments. A current limitation is the bond line integrity of the fire exposed components as the combustion characteristics of failed char pieces on the floor are currently unknown.

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Timber under real fire conditions – the influence of oxygen content and gas velocity on the charring behavior

Cited by 15 publications

References 5 publications

Fire Design of CLT in Europe

Fire Design of CLT in Europe

Brandeinwirkung auf Holzbauteile im Prüfofen und bei realen Bränden

Structural Timber In Compartment Fires – The Timber Charring and Heat Storage Model

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