Abstract 

Although natural fire is allowable by Brazilian standards of the fire safety design, there are not any specifications to appliance to the ordinary buildings constructed with the typical construction and structural materials from Brazil. This paper describes the behavior of a cold formed steel framed structure in response to a real fire occurred in a residential apartment, on 3rd January, 2002. A set of residential buildings that constructed in 1995 in Limeira city, State of Sao Paulo, Brazil, is composed by four identical four-storey blocks of eight apartments per floor housed by poor people; each apartment has 44.3 m2 of total area, including two bedrooms, one living room, bathroom and kitchen. The structure and masonry were built, respectively, by cold formed steel and ordinary bricks. The Brazilian Code allows this type of buildings be neglected from structural checking in fire situations.

The fire has started in a little Christmas tree into an apartment on the fourth floor. Although the fire had been developed without any restraint, nothing spread to the neighboring apartments occurred, and not even the damaged structure presented risks of global or partial collapse. In this case study, a real fire in a residential apartment was modeled, as well the structural fire resistance; the maximum fire temperature reached during the burning on the structural material was assessed by metallographic tests and computational modelling, to the further comparative analysis between the theoretical and actual results.

A CFD scenario, representative from the actual building geometry, materials and fire behavior was modeled by means of the software SMARTFIRE. Details of the fire scenario as  actual fire load, material composition and location of the furniture imputed to the modeling were obtained from the apartment's owner and measurements taken during the site inspection; after that, a steel thermal analysis in fire situation was conducted by means the software Supertempcalc, and the structural analysis of the steel frame was performed according to the expressions recommended by the Brazilian Standard for design of cold formed steel for room temperature, similar to AISI/USA, but using the strength reduction factors recommended by Eurocode 3 part1.2.

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