Performance of solid steel beam under fire for different beam slenderness

The present work is intended to study the behaviour of solid steel beam (SSB) under the ISO834 fire curve for different beam slenderness when it is subjected to three-sided exposure and four-sided exposure condition. The properly validated finite element based thermo-mechanical analysis is carried out to predict the performance of SSB under elevated temperature. The present study takes into account the transient temperature effect and the geometrical and material non-linearity. The section selected for this study is a universal beam section UB356×127×39. The considered beam slenderness (span to depth ratio) for this study is varied between 15 to 35, as these slenderness are generally preferred in practice. The eccentric hinge-hinge boundary conditions at the bottom flange are applied to the beam and beam is assumed to be laterally supported at top flange all along its length, and the bottom flange is not restrained laterally along its length. The various parameters considered for the present study include: beam slenderness, load ratios, and exposure condition of the beam under uniformly distributed loading. The performance of SSB under fire is compared using mid-span deflection, lateral displacement, limiting deflection, limiting temperature, and fire resistance time of the SSBs. This study depicts that there is a significant effect of beam slenderness on the behavioural aspect of SSB under elevated temperature.