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The main goal of this work is to present a numerical model to assess the fire safety of wooden slabs with rectangular perforations on a ceiling. These typical constructions have good sound absorption, heat insulation and relevant architectonic characteristics. They are used in many civil applications: concert and conference halls, classrooms, nurseries, airports, hotels, shopping, universities, and many other public buildings. These panels are normally installed at a lower level in building constructions to facilitate essential maintenance. Depending on the installation requirement, the perforated wooden slabs could have insulation material inside the cavities. In this work the proposed numerical model could be used for different design constructive solutions. In order to guarantee the fire rating in a typical used perforated wooden slab, a transient thermal analysis with nonlinear material behaviour will be solved using ANSYS program. This study allows for verifying the evolution of the temperature and the char-layer throughout a wooden slab with different rectangular perforations and considering the insulation effect inside the cavities. The developed numerical model allows future studies and simultaneously characterizes the effect of rectangular perforations in wooden slabs to minimize the fire risk. The numerical model can easily be adjusted for other constructive solutions, to facilitate fire safety validation, in buildings with several wooden slab assemblies used in floors or in ceiling applications.

Wood is a natural material and is submitted to many constantly changing influences. Wood as a construction material presents many advantages due its high strength and stiffness to height ratios. The main advantages of timber constructions, relatively to the use of other materials, are: ease of construction and maintenance, pleasant appearance, renewable resource, lightweight. The high vulnerability of wood due accidental conditions requires a rigorous thermal and mechanical assessment. Safety rules and others guidelines should be useful and used for wood applications. The fire safety of this type of material involves prevention, inhibition and detection. This involves appropriate design rules, installation, construction and maintenance of the wood material in different applications. If wood is submitted to a sufficient heat, a degradation thermal process occurs, producing gases accompanied by loss in serviceable cross-section and its weight. The factors which affect the burning behaviour of wood will determine the charring rate. Design models of wood structures at high temperatures take into account the cross-section loss due to char formation. This work contributes with an experimental program for evaluation of char-layer thickness in wood elements under high temperatures. Experimental results have shown a difference in charring rate and reproduced reasonably well by numerical results with the thermal properties of Eurocode 5 and a ratio of 1.5 applied by the Longitudinal/Transversal thermal conductivity. This study it allows to verify the evolution of the temperature and the char-layer throughout a wooden specimen, in different fibres orientation. The experimental results confirm that grain orientation of wood influences the char-layer evolution. The numerical program reveal of great importance also for char-layer determination. The char-layer thickness was calculated with the numerical results obtained from Ansys program and compared with experimental tests.

Wood material is being used increasingly for structural engineering applications in buildings and other special engineering productions. To assess safety rules, this type of element should have sufficient mechanical resistance to guarantee the design loads. Wood is a natural material and is subject to many constantly changing influences. High wood vulnerability, due to accidental conditions, requires rigorous thermal and mechanical assessment. The combustion and the chemical phenomena occurring in the wood during an accidental situation of elevated temperature is a complex study issue. When wood structures are exposed to high temperatures, the burned wood becomes a char layer, which loses all strength, but the insulating temperature rises in the core of the material. The charring rate is more or less constant and mainly depends on the density and moisture content of the wood. Safety rules and guidelines should be useful for different wood applications. The fire safety of this type of material involves prevention, inhibition, detection and evacuation. This involves appropriate design rules, installation, construction and maintenance of the wood material applications. This paper proposes an experimental and a numerical method for charring rate determination in pine wood. Different pine sections will be tested and submitted to high temperatures using a heating power unit based on electrical resistances. The temperature results will be measured through a wood profile during time heating exposure. Using appropriated material properties and boundary conditions, reasonable predictions of the charring layer with a finite element analysis method can be provided. The thermal response obtained with the finite element formulation will be compared with experimental results in several series of wood pine profiles. The char layer thickness will be determined.

Numerical analysis of hollow tubular sections is used as a starting tool to establish the reliability assessment of these elements when mechanically or thermally loaded. To quantify the material deformation behaviour of these elements resulting from ground motion, crack propagation, effects from high temperatures, theoretical and experiments analyses can be used for testing a service reliable guarantee. Structural hollow sections have excellent static properties, not only with regard to buckling and torsion, but also in the overall design of members. They can offer economic advantages compared to open sections. It is possible to change the strength by varying the wall thickness or filling the section with other material without changing the external geometry. Flexibility is an important parameter in hollow tubular systems when subjected to thermal or mechanical loads. This work presents a numerical analysis technique based on the finite element method for thermal and mechanical nonlinear behaviour. Temperature field will be calculated according to non-steady conditions when submitted to standard ISO834 and non-linear material properties foreseen in Eurocode standards (EC1 and EC3). This work will present a complete study of the flexibility analysis for a wide range of pipe dimensions, and the obtained results are then compared with design rules. temperature, equivalent stress, tubular section, flexibility