Steel Buildings in Europe

Part 7: Fire Engineering 7 - 45 purlin fire wall beam stay column protected column purlin fire wall protected lattice beam beam stay a) Fire wall inserted between two independent steel framework b) Fire wall fixed to one flange of columns Figure 5.22 Design detail near fire walls parallel to steel frame with lattice beam 5.6.4 Recommendations for bracing system The requirement for no collapse towards the outside of the building in the the longitudinal direction (perpendicular to steel frames) can be satisfied using appropriate bracing systems. Specifically, each compartment must have its own bracing system. Fire wall perpendicular to the steel frame Figure 5.23 (a) illustrates the situation where the fire wall is perpendicular to the steel frame. For this situation:  Use additional vertical bracing systems at both ends of fire wall, to ensure integrity of wall. These bracing systems should be designed to support a lateral load taken as 20% of that due to normal wind actions (according to the combination of actions for the fire situation), calculated for a gable area that is limited to the width between gable posts.  Provide double bracing systems (i.e. have bracing systems on both sides of fire walls) or protect the bracing system.  The bracing systems must be arranged in a way that they will not cause problems for normal temperature design, for example by compromising movement of an expansion joint. Fire wall parallel to the steel frame Figure 5.23 (b) illustrates the situation where the fire wall is parallel to the steel frame. For this situation:  Install bracing systems (vertical bracing and horizontal bracing on roof) in each compartment. This solution may lead to additional bracing systems for normal conditions.  Design each bracing system to provide adequate stability in normal condition and to support in fire condition a horizontal uniform load [N/m] taken as F = 1,19  ( G + ψ 1  S n )  l f , where l f is the spacing between steel frames, G is the permanent action, including service overloads, S n is the