The adoption of timber, specifically cross-laminated timber (CLT), as a primary construction material is gaining traction due to its carbon sequestration capabilities, environmental advantages, and potential for precision manufacturing. However, the combustibility of wood raises legitimate concerns about fire safety in timber-based residential buildings. This paper investigates the fire performance of timber in a residential context, attempting to fill knowledge gaps and outline strategies for improving fire robustness in timber-built dwellings. Through comprehensive experimental studies on residential-type enclosures constructed with CLT panels, this research explores different configurations and the effects of varying degrees of non-combustible protective lining. The findings underscore the significance of considering timber surface exposure and adopting effective encapsulation strategies in CLT buildings. It has been estimated that the exposure of timber walls leads to a proportional increase in heat release rate, corresponding to the area of exposed timber surfaces and their charring rates. Consequently, the external flame has a larger projection, resulting in a much greater heat flux to the façade. Furthermore, threshold conditions for initial flaming self-extinguishment of timber defined in literature of 44.5 ± 1.2 kW/m2 have been found to be applicable to the experiments conducted in this research. Finally, it has been observed that partial encapsulation, where the protective lining will likely fall off during a fire, may hinder rather than increase the likelihood of self-extinguishment. This work contributes towards a nuanced understanding of fire dynamics in timber structures, offering insights for safer and more effective design strategies for CLT-based construction.

This paper provides further understanding of the fire performance of exposed cross-laminated timber (CLT) in large enclosures.An office-type configuration has been represented by a 3.75 by 7.6 by 2.4 m high enclosure constructed of non-combustible blockwork walls, with a large opening on one long face.Two experiments are described in which propane-fuelled burners created a line fire that impinged on CLT ceilings.The first experiment had a smooth CLT soffit, with the CLT formed from 160 mm thick panels (40-20-40-20-40 mm).The second experiment adopted the same CLT but included a 400 mm deep, 200 mm wide glulam beam half-way along the length of the enclosure.In both experiments, the lamella of each CLT were bonded using a standard polyurethane adhesive.The facing lamella of the CLT was not edge bonded.The results indicate the importance of consideration of the impact of ceiling protrusions, such as down-stand beams, with differences in both radiative heat flux to the ceiling and floor observed between the two cases.Considering large contemporary open plan office enclosures, this would likely translate to differences in spread rate within an enclosure and time to auto-extinction of flaming combustion which should be addressed by designers.

This paper provides understanding of the fire performance of exposed cross-laminated-timber (CLT) in large enclosures. An office-type configuration has been represented by a 3.75 by 7.6 by 2.4 m high enclosure constructed of non-combustible blockwork walls, with a large opening on one long face. Three experiments are described in which propane-fuelled burners created a line fire that impinged on different ceiling types. The first experiment had a non-combustible ceiling lining in which the burners were set to provide flames that extended approximately halfway along the underside of the ceiling. Two further experiments used exposed 160 mm thick (40-20-40-20-40 mm) loaded CLT panels with a standard polyurethane adhesive between lamella in one experiment and a modified polyurethane adhesive in the other. Measurements included radiative heat flux to the ceiling and the floor, temperatures within the depth of the CLT and the mass loss of the panels. Results show the initial peak rate of heat release with the exposed CLT was up to three times greater when compared with the non-combustible lining. As char formed, this stabilised at approximately one and a half times that of the non-combustible lining. Premature char fall-off (due to bond-line failure) was observed close to the burners in the CLT using standard polyurethane adhesive. However, both exposed CLT ceiling experiments underwent auto-extinction of flaming combustion once the burners were switched off.

In der vorliegenden Arbeit werden, aufbauend auf die Bemessungsdiagramme für einen Biegeträger einer Dachkonstruktion mit homogenem Stabquerschnitt [ 1 ], die Erweiterung um den inhomogenen Stabquerschnitt (geschichteter Verbundquerschnitt) sowie die Implementierung der Schwingungsnachweise gezeigt. Während bei den Bemessungsdiagrammen für den homogenen Stabquerschnitt sowohl die ULS‐ als auch die SLS‐Nachweise von Relevanz waren, treten bei Erweiterung um die Schwingungsnachweise sowie aufgrund der Einflüsse des inhomogenen Querschnittsaufbaues vorrangig die SLS‐Nachweise auf. Das Schwingungsverhalten von Deckentragwerken wird wesentlich durch die Lagerungsbedingungen beeinflusst. Die Einspanneffekte im Bereich des Anschlussdetails Wand‐Decke zufolge der Geschossauflasten werden bei der Bestimmung der Eigenfrequenz berücksichtigt.

This paper presents an application of design charts for inhomogeneous cross-sections (layered composite section) and the implementation of vibration design criteria as extension of the charts for beams with homogeneous cross-sections in roof-structures according to selected European Design Standards published in [1]. While ULS and SLS criteria were nearly equally governing for the homogeneous cross-section, mainly SLS criteria are now governing due to the extension with vibrations and the influences of the inhomogeneous cross-sections. The vibrational behavior of floors is essentially influenced by the support conditions. Effects of moment restraints at the wall-floor-wall detail, activated by wall-loads from stories above, are systematically being taken into account.

Um realitätsnahe Berechnungen von Holzkonstruktionen mit modernen numerischen Berechnungsverfahren, wie z.B. der Finite-Elemente-Methode (FEM) durchführen zu können, benötigt man geeignete Werkstoffgesetze. Ein solches Materialmodell haben Mackenzie-Helnwein et al. (2005) für technologisch einwandfreies, d.h. fehlerfreies Fichtenholz entwickelt. Dieser Beitrag behandelt die anwendungsorientierte Umsetzung des genannten Werkstoffmodells, dessen Implementierung in eine FE-Software sowie die Durchführung von numerischen Tragfähigkeitsanalysen mit Hilfe der FEM und die Validierung des Materialmodells durch den Vergleich der Ergebnisse der FE-Simulationen mit parallel durchgeführten Versuchen auf Strukturebene (Fleischmann 2005). Des Weiteren werden einige Aspekte im Zusammenhang mit der Normung in einem der beiden dokumentierten Beispiele behandelt.