FIRE RESISTANCE OF COMPOSITE FLOORS: NUMERICAL EVALUATION OF DESIGN PARAMETERS
Antonio Maria Claret de Gouveia1; Ana Maura Rocha1; Luciana Gomes Castanheira1; Helder Luis Fransozo1; Augusto Cesar da Silva Bezerra2; João Trajano da Silva Neto3; Paola Macedo G Dias3; Elaine Martiles Guimarães4; José Geraldo da Silva Araujo4
1 Universidade Federal de Ouro Preto; 2 Centro Federal de Educação Tecnológica de Minas Gerais; 3 Instituto Federal de Minas Gerais; 4 REDEMAT - Universidade Federal de Ouro Preto
doi:10.20906/CPS/CILAMCE2017-1124
Resumo
Composite floors are commonly used in commercial, residential and office buildings. The typical structural modulus consists of steel columns, main border steel beams, secondary steel beams and a concrete slab supported by a steel deck. Designing a composite floor at ambient temperature is a relatively simple task. Some technical standards like the Brazilian NBR 6118:2014 or, for example, the Americans ACI 318-11 and the ANSI/SDI C-2011 are applicable for design at ambient temperature. Considering fire conditions, the floor designed at ambient temperature is verified to accomplish requirements of fire resistance. Concerning to stability in fire during the required time of fire resistance - TRRF passive fire protection may be needed. The passive protection of columns and of main border beams avoiding protection of secondary beams is accepted as the more economic fire protection strategy. When using FEM analyses, limiting criteria of maximum calculated panel deflection in fire is imposed. This work numerically evaluates the influence of the total area of reinforcement bars and of the characteristic resistance of concrete in looking for a stable panel configuration in fire. It is supposed that changing these parameters it may be possible to pass from an unstable to a stable condition in fire avoiding at the same time the need of passive protection of secondary beams.
Palavras-chave: composite steel floors; structural behaviour in fire; design parameters in fire situation