Steel Buildings in Europe

Part 7: Fire Engineering 7 - 44 first vertical member fire wall protected column fire protection lattice beam fire Wall protected column fire protection first vertical member lattice beam a) Fire wall inserted between the flanges of columns b) Fire wall fixed to one flange of columns Figure 5.21 Design detail near fire walls perpendicular to steel frame with lattice beam Where fire wall is parallel to steel frame Figure 5.22 illustrates the situation where the fire wall is parallel to the steel frame. For this situation:  It is not practical to provide a wall in the plane of a frame, because it is difficult to make it continuous through the depth of the lattice beam. roof, Fire walls parallel to a frame are therefore usually either beside and in contact with the steel frame or between two independent steel structures.  Where the fire wall is attached to a steel frame, the columns and beams must be fire protected (see Figure 5.22 (b)). Moreover purlins and beam stays near the wall must be fire protected over a minimum length corresponding to the distance from the wall to the joint purlin/beam stay when the roof structure is made of purlins.  Where the fire wall is inserted between two independent steel structures, no fire protection is needed (see Figure 5.22 (a)). If columns are protected, the thickness of fire protection material may be calculated assuming a critical temperature of 500°C and the same fire resistance as required for fire walls. Fire protection should be provided over the full height of the columns. If lattice beams are protected, the thickness of fire protection material may be calculated assuming for the section factor: a steel section exposed on four faces for bottom chords, vertical members and diagonals; and three faces for top chords. A standard fire exposure of one hour and a critical temperature of 500°C may be assumed. Fire protection should be provided over the full length of the lattice beams. The thickness of fire protection material applied to purlins and beam stays may be simply 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.