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Proposal for standard test method to evaluate the performance of cross‐laminated timber exposed to fire In recent years, cross‐laminated timber (CLT) has become a popular wood‐based product for high quality and innovative timber construction. As with any building product, the fire performance and fire resistance of CLT elements must be carefully assessed when designing buildings. The adhesive used in the glueline of CLT plays an important role in the fire design. However, at present, the European standards do not provide a test method to assess the adhesive properties in CLT exposed to fire. At ETH Zurich, fire tests were carried out with CLT floor elements in which adhesives with various properties were tested in fire. This article presents the results of these fire tests and shows a possible European test method for the classification of adhesives. It is shown that the mass loss of the CLT elements during an EN/ISO standard fire can be used to evaluate the integrity of the surface gluing in fire. [ABSTRACT FROM AUTHOR] more...

Abstract: Fire exposure of timber members in furnace tests and real fires Currently, some discussions question the validity of furnace test results for timber members, which are carried out according to standards. It was stated that combustible and incombustible products are exposed to different thermal exposures when tested in furnaces. Additionally, some experts think that massive timber elements, e. g. cross‐laminated timber (CLT), cannot be tested in furnaces, as these products increase the fire load and thus statements in the traditional framework of fire resistance testing are not possible. Further, existing design models and models currently under development for CLT were questioned. This study shows similarities and differences between incombustible and combustible building products when tested in furnaces. It is shown that the thermal exposure of combustible building products in furnace tests are similar to incombustibles, even if solid elements like plates, e. g. CLT are tested. Further, it is shown that the additional fire load due to combustible products cannot be determined directly by standard fire tests. If necessary, other fire safety engineering methods should be used. Any additional fire load due to combustible products will not lead to higher temperatures in a fire compartment but will mainly change the flames through openings on the façade. Currently, this circumstance is taken into account in some building codes by several regulations; it is expected that further models will be implemented in Eurocode during the currently ongoing revision. [ABSTRACT FROM AUTHOR] more...

Design models for timber structures with fire-resistance requirements usually take into account the loss in cross section due to charring and the temperature-dependent reduction in strength and stiffness of the residual cross section. Standards for glued timber elements like glued-laminated timber beams have assumed that structural adhesives do not influence the fire resistance, but further specifications of adequate adhesive requirements are missing. Investigations were therefore conducted to determine the influence of different adhesives on the load-carrying behavior of glued-laminated timber beams in fire. Large-scale fire-resistance tests in combination with extensive finite-element analyses showed that a modification of the zero-strength layer thickness of d0 = 7 mm currently used in a standard design code should be discussed for glued-laminated timber loaded in bending in a future release of this design code. An increase of the zero-strength layer d0 considering the finger-joint strength depending on the approved structural adhesive is not needed. [ABSTRACT FROM AUTHOR] more...

Fire behaviour of cross-laminated timber Cross Laminated Timber (CLT) is currently used in modern timber structures for load-bearing wall, floor or roof elements as a high quality, innovative and cost-effective structural element. Careful planning and implementation ensures the safe use of CLT in buildings with increased fire protection requirements and in accordance with the requirements of building-design standards (e. g. EN 1995-1-1 and EN 1995-1-2) [1, 2]. Worldwide, many fire tests with CLT have been per-formed to investigate the influence of different cross-sectional build-ups and various adhesives on the fire resistance of CLT floor and wall elements. This paper gives an overview of the extensive investigations, main outcomes are summarized and recommendations on the fire design of CLT elements are given. The investigations show that an adequate data base exists to reliably describe the fire behavior of CLT. [ABSTRACT FROM AUTHOR] more...