Steel Buildings in Europe

Part 2: Concept Design 2 - 55 The critical beam check is often torsional resis tance, or combined torsion and lateral torsional buckling resistance in the construction condition (with loads on one side only). 5.6.3 Services integration Main service ducts are located below the beams with larger services equipment located between beams. 180 min. 30 75 min. 50 50 min. 75 min. (a) Units sitting on downstand beam (b) Units sitting on shelf angle beam Figure 5.14 Floor construction with precast concrete units in non-composite construction 25 min. Figure 5.15 Bearing and clearance requirements for precast units on shelf angle beams 5.6.4 Fire protection Fire protection m ay be spray, board or an in tumescent coa ting to the beam . Shelf angle beam s can achieve 30 minutes fire resistance by up-turning the angles, (the vertical leg is above the projecting leg, as shown in Figure 5.15) so that they remain relatively cool in fire. 5.7 Integrated beams with precast concrete units 5.7.1 Description Precast concrete units m ay be used as part of a slim floor or integ rated beam system, in which the b eams are contained within the floor depth, as illustrated in Figure 5.16. Two forms of steel beams are commonly used: