Influence of boundary conditions on the thermal response of selected steel members

Abstract

In the paper the influence of boundary conditions on the thermal response of selected steel members subjected to fire loads is investigated. Simply supported and restrained steel beams subjected to uniformly distributed load and fire accidental action are analysed using the standard ISO-fire curve. The iterative procedure to investigate critical temperature is used. At each increment of temperature the ultimate limit state is checked using the EC recommendation. The special attention is focused on axial action occurring due to thermal elongation. The illustrative examples show that, proper modelling of the beam’s boundary conditions plays an important role in describing and understanding the real behavior of elements in fire conditions. Moreover, beam’s boundary conditions can change structural response and result in reduction of critical temperature and fire resistance time.