Steel Buildings in Europe

Part 7: Fire Engineering 7 - 40 n is the total number of fastenings (uniformly distributed along the height) i  is the maximum lateral displacement obtained from relation (26) [m] Fire protection of steel elements near to fire walls The requirement that there should be no fire propagation between different compartments and no progressive collapse (i.e. the integrity condition of fire walls must be preserved and the cold parts of the structure must remain stable), leads to the requirement that that columns used as supports of fire walls must achieve the same fire resistance as required for fire walls. In common cases, these fire requirements lead to the application of fire protection to the columns. On the other hand, columns which do not support fire walls will not require fire protection. Additionally, structural members that could damage fire walls (such as beams and purlins near or crossing the walls) will also have to be fire protected. 5.6.2 Recommendations for steel portal frames Fire wall perpendicular to steel frame Figure 5.17 illustrates the situation where the fire wall is perpendicular to the steel frame. For this situation:  Columns that are built into or near a wall must be fire protected.  Where fire wall is inserted between the flanges of the columns, no additional fire protection is needed for the roof beams (Figure 5.17 (a)).  Where portal frames do not have haunches and fire wall is fixed to one flange of columns, fire protection must be applied to any beam crossing the fire wall (on the side of the wall) over a minimum length of 200 mm beyond the wall limit. This protection allows a shift of the plastic hinges away from the walls and thus prevents damage to the wall as a result of the collapse of the beam (see Figure 5.17 (b)). Where portal frames have haunches, no fire protection is needed for the beams.  Purlins do not cross the fire wall in this situation and no special considerations are required. The thickness of fire protection material applied to columns may be calculated assuming a critical temperature of 500°C and the same required fire resistance as the fire walls. Fire protection should be provided over the full height of columns. If beams are partially protected, the thickness of fire protection material may be calculated assuming a steel section exposed on four faces for the section factor, a standard fire exposure of one hour and a critical temperature of 500°C.