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This study proposes an analytical model for the evaluation of the mechanical behaviour of circular hollow section columns infilled with steel fibre-reinforced concrete when exposed to elevated temperatures in a fire situation. This work includes the discussion of the results from a sensitivity analysis conducted through numerical simulation and the development of an analytical model based on the prEN1994-1-2:2021 European standard for the design of reinforced concrete structures exposed to fire. The sensitivity analysis aims to compare the fire resistance of centrally and eccentrically loaded circular hollow section columns infilled with plain and steel fibre-reinforced concrete. The proposed analytical model for determining the design buckling load of composite steel fibre-reinforced concrete-filled tube columns in a ?re situation is ready to serve as an annexe or supplementary technical document to the EN1994-1-2:202x standard.

This article presents the possibility of increasing the fire resistance of a steel member with the use of an OSB (Oriented Standard Board) cladding. Correct design and dimensioning of the OSB cladding to fulfil the targeted fire resistance of the steel member is the main challenge with this type of cladding. The problem lies in the addition of combustible material on the surface of the steel member. When the wood-based material burns, additional heat is generated, and this raises the temperature of the surrounding gas. However, wood material benefits from its extraordinary behaviors when exposed to fire. The burned part forms a char layer that insulates the solid materials below it. It is necessary to ensure the integrity of the cladding and to prevent its premature failure. The aim of the work presented in this article was to determine the functionality of an OSB cladding as a fire protection layer for a steel beam. For this purpose, an FE (Finite Element) model of the heat transfer is developed and is validated against measured data from a fire test in a horizontal furnace. The progression of the charred layer is determined from the validated FE model, and is compared with the standard linear charring rate.

This article presents the validation of the Computational Fluid Dynamics (CFD) model of the Room Corner Test (RCT). In the RCT experiment, a natural fire with two columns and one beam is studied. The specimens were made of spruce wood. The CFD model integrates the calculation of complex pyrolysis. The Fire Dynamics Simulator (FDS) was used, and the input data was created. In the experience of previous models, emphasis was placed on the selection of input data for the pyrolysis model. Various pyrolysis models with a single reaction pattern or with parallel reactions were studied in a numerical simulation. This work provides insight for advanced modelling of wood samples in a natural fire, taking into consideration the pyrolysis model. The CFD model with pyrolysis, considering massive specimens, has not previously been adequately validated and presented. To show the applicability of the model, the development of the char layer of the timber column most exposed to fire is presented.