Numerical and analytical study for the determination in natural fire situation of the critical load on steel beams under concentrated load / Estudo numérico e analítico para determinação em situação de incêncio natural da carga crítica de vigas de aço com carga concentrada
AUTOR(ES)
Líris Silveira Campêlo
DATA DE PUBLICAÇÃO
2008
RESUMO
Fire over a structural system is considered an accidental load and can generate structural collapses. The catastrophic effects of a fire on a structural system should always be avoided with preemptive actions. Therefore, it is essential to have the appropriate knowledge of the structure behavior under fire and to take appropriate actions to avoid its collapse during a fire incident. This work presents a numerical and analytical study of the behavior of steel beams with I-section under natural fire and under a concentrated load. Initially, the phenomenon of fire is reviewed, fire models recommended by Standards are presented, the weakening of the material properties is pointed out, and the heat transfer mechanisms are described. An analytical formulation, based on the energy method, is presented for the determination of the nominal critical load concentrated on a steel beam. This formulation takes into account the lateral instability with flexural-torsional buckling of the beam and considers the different heating conditions of the beam flanges, and the consequent stiffness asymmetry generated on the I-section flanges during fire. Several cases of natural fires with a variety of fire loads, aeration ratios, and time durations of fire are studied for steel beams typically used in Brazil. Considering the temperature difference on the beam flanges, and using the formulation presented here; it is demonstrated that the critical nominal loads are higher than those recommended by the Brazilian Standard.
ASSUNTO(S)
estruturas carga crítica incêndio
Documentos Relacionados
- Determinação da carga crítica de instabilidade lateral no regime linear elástico, em vigas de madeira laminada colada (MLC)
- Sobre o comportamento de pilares de aço em situação de incêndio.
- Análise numérica de seções transversais e de elementos estruturais de aço e mistos de aço e concreto em situação de incêndio
- Modelos numéricos de vigas mistas de aço e concreto pertencentes a sistemas de pisos mistos de pequena altura em situação de incêndio
- Modelos numéricos de pilares de aço em situação de incêndio considerando a influência da restrição axial