Fire resistance of timber-concrete composite slabs
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ORIGINAL ARTICLE
Fire resistance of timber-concrete composite slabs A simplified method Anita Ogrin
. Tomazˇ Hozjan
Received: 20 March 2020 / Accepted: 23 July 2020 / Published online: 20 August 2020 Ó The Author(s) 2020
Abstract The paper presents a simplified method for calculation of resistance of a TCC slab in fire conditions.Within the method the tensile and the compressive failure criteria in the outermost fibres of the cross-section are checked. The influence of the fire is applied through one-dimensional charring of the timber part of the cross-section in accordance with current standards on reduction of properties of materials. The concrete-timber connection is assumed to be ideal during the determination of resistant moment of the TCC cross-section. On the other hand, the calculation of the deflection of the TCC slab is conducted with the reduction of the connection’s rigidity. The ineffective zone of the timber as well as the cracked tensile zone of concrete part do not contribute to the effective stiffness of the TCC slab. The method is validated against the results of full sized fire tests of one way spanning TCC slabs form literature. Calculated and experimentally determined midspan deflections and failure times of the TCC slabs are compared and their considerable agreement is observed. Due to its convenience and accuracy, the present simplified method represents a useful tool for designers of TCC structures in fire conditions.
A. Ogrin (&) T. Hozjan Faculty of Civil and Geodetic Engineering, Jamova cesta 2, 1000 Ljubljana, Slovenia e-mail: [email protected]
Keywords Timber-concrete composite Slab Fire Simplified method Effective stiffness Laminated veneer lumber
1 Introduction Composite structural elements represent popular and, when properly designed, one of the most optimized structural bearing systems. They are used as a bearing system of new buildings and infrastructure as well as for rehabilitation and strengthening of existing ones. The latter can be achieved through the replacement of the entire damaged structural element with a composite one or through an application of an additional material layer to the existing element, which can increase its initial bearing capacity, stiffness and/or ductility. Other properties of the original element, such as sound and thermal insulation as well as fire resistance, can also be improved in the same way. Lately, there has been an increase in the usage of composite systems made of timber and concrete, mainly due to the favourable properties of timber. Timber, being a natural resource, is a renewable and recyclable material and it requires low energy for production compared to other widely used building materials such as concrete or steel. In principle, composite structures are assembled in such a way that each off the materials can be fully exploited. The
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upper layer of timber-concrete composite (TCC) systems is usually made of concrete due to the high compressive stren
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