the boundary conditions (Twilt, et al. ). The more fire of the

the boundary conditions (Twilt, et al. 1991). The more conservative effective length factor (0.7) should be used for assessing the buckling length in fire of columns on the top floor and for the columns at the edge of a building with only one adjacent beam. The higher reduction factor (0.5) may be used for all other columns. The schematic structural behaviour of columns in braced frames is shown in Fig. 3. The above rule is also applied in EC3 (1992) and EC4 (1990).