Steel Buildings in Europe

Part 4: Detailed Design 4 – 9 1 4 3 5 2 H H H F H H H H H H b b b b b Ed (a) (b) (c) (d)      At each floor level, H i = 0,025  V Ed, i where V Ed, i is the total design load applied at that floor level (a) cross bracing, only diagonal in tension participating (b) diagonal bracing (c) horizontal K bracing (d) vertical K bracing Figure 2.3 Practical alternative arrangements for multi-storey bracing: 2.6.3 Design procedure Select one of the bracing arrangements shown in Figure 2.3. Verify that, in the columns and beams of the system to be braced, the axial stresses calculated on the gross cross-section due to resistance of the horizontally applied loads of 2,5% of vertical applied loads alone do not exceed 30 N/mm 2 . (This is to limit the elongations of the bracing and shortenings in the columns.) If the stresses are higher in the columns, either larger sections must be chosen, or the spacing of the columns ‘ b ’ in Figure 2.3, must be increased (but not exceeding 12 m). If the stresses in the beams are larger, either a larger section must be chosen or the bracing arrangement must be changed. Size the bracing by conventional design methods, to resist horizontal applied loads of 2,5% of vertical applied loads, ensuring that axial stresses on the gross cross-section of the bracing do not exceed the values given in Table 2.1. For intermediate floors, either the stress limits in Table 2.1 for the top floor should be used, or a higher stress may be found by linear interpolation between the stress limits according to the height of the bottom of the storey considered. If the externally applied horizontal load, plus the equivalent horizontal forces from imperfections, plus any other sway effects calculated by first-order analysis, exceed 2,5% of the vertical loads, check the resistance of the bracing to these loads. The stress limitations in Table 2.1 should not be applied when checking this load combination.