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The main objective of this paper is to develop a numerical model for thermal analysis of wooden slabs with cavities, when subjected to the fire action. The temperature profiles, the charring depth layer and the charring rate will be determined using the finite element method with ANSYS program. The numerical calculation of the temperature profiles will be obtained through a transient and a non-linear thermal analysis, where the material properties are temperature dependent. These properties were established in accordance with the referenced data and numerically calibrated. Two different models of wooden slabs with cavities were studied. One model characterizes a wood slab with void cavities and other with insulation material. To characterize the fire resistance in wooden slabs with insulated cavities or void cavities, different typical curves of charring depth layer will be obtained. A numerical procedure is proposed to identify the heating action into the slab cavities. All numerical results permit the verification of the fire safety in wooden slabs with cavities.

The numerical and experimental determination of the buckling design moment of steel I beams is influenced by the type of support and load restrain during the mechanical and thermal load. As a result of beam temperature rise the axial movement will be allowed and the type of load and support restrain will be compared from fully to unrestrained state. For this study a simple supported beam is bent about its axis of greatest flexural rigidity. Taking into account the geometric and material imperfections, the beam may twist before it reaches its strength limit state. This flexural stability limit state is most commonly referred to as lateral torsional buckllng of a beam. The twisting af the beam Occurs when the compression flange becomes unstable as a result of being subjected to flexural induced axial stresses. The design rules in Eurocode 3 related to design of steel structures in fire conditions presents their expressions as a function of the type of support and load. A particular attention will be paid to the type of experimental support and to the numerical finite element model used. The aim of this work is to investigate the value of the effective buckling length of steel 1 beam under the mentioned conditions. A relation between the beam buckling resistance and the lateral bending stiffness will be presented.

In this paper, experimental tests on lateral torsional buckling of steel I Beams under fire conditions are presented. The beam, spans varies from 0.5 to 6.5 [m] length and the temperature was risen up to 600 [ºC]. The initial conditions of the steel beams were measured. The residual stress state was characterized by the hole drilling method, using specific strain gauges, The geometric imperfections was measured by means of a laser beam and the cross section of the beams was dimensionally controlled. The methodology to the thermo-mechanical load was first heat the beam and let it expand for controlling the mechanical load position, and finally increase the load step by step. The aim of this work is to validate the proposal for lateral torsional buckling design resistance suggested in ref.[1] based on numerical results. A set of experimental results• are presented, relating the collapse load with the mid span movement of the beam cross section, when submitted to concentrated moments at the ends and to a uniform distributed load, duo to the ceramic mat, the insulation material weight and the self weight of the beams.