Simulating the behavior of restrained steel beams to flame impingement from localized-fires

Steel structures may be exposed to localized heating by a fire source nearby. Flame impingement from localized fire may lead to high temperatures in the exposed steel members, which may lead to structural failure. This paper numerically investigates the thermal and mechanical behaviors of restrained steel beams exposed to flame impingement from localized fires. Four steel beams with different dimensions and restraints were considered. Both developing and steady burning fires were investigated. The standard ISO834 fire was also used for comparison. The study finds that the temperature distributions within the steel beams subjected to flame impingement are highly non-uniform both across and along the beams. Along the beam length, the temperatures near the fire source may be hundreds of degrees higher than those far from the fire source. Due to different temperature distributions, the deformation mode for restrained steel beam subjected to flame impingement may be significantly different from that of a beam subjected to the standard ISO834 fire. The failure temperatures for restrained steel beams subjected to localized fires may be higher or lower than those for restrained beams subjected to the standard ISO834 fire. Reliance on the standard fire may lead to an unconservative design if the potential real fires are localized fires.

► In localized fires the steel temperature is highly non-uniform.
► Failure model in localized and standard fire might be different.
► Failure temperature in localized fire can be much lower than that in standard fire.
► Standard fire may lead to unconservative design.