The same eight-storey building considered in previous chapters is utilised in this example. The layout of the structure is reproduced in Figure 6.17. The main seismic design checks are carried out for a preliminary design according to EN 1998-1. For the purpose of illustrating the main seismic checks in a simple manner, consideration is only given to the lateral system in the X-direction of the plan, in which resistance is assumed to be provided by MRFs spaced at 4 m. It is also assumed that an independent bracing system is provided in the transverse (Y) direction of the plan. Grade S275 is assumed for the structural steel used in the example.
The gravity loads are adapted from those described in Chapter 3, and are summarised in Table 6.3. On the other hand, the seismic loads are evaluated based on the design response spectrum and on the fundamental period of the structure, which is estimated to be 1.06 s from the simplified expression in EC8 (Cl. 126.96.36.199.2). The total seismic mass, obtained from the self weight as well as an allowance of 30 per cent of the imposed load, is found to be 8208 t.
198 A.Y. Elghazouli and J.M. Castro
re 6.17 Frame layout
Table 6.3 Summary of gravity loads
Type of Load
150 mm thick solid slab 3.6
External walls 3.25
Internal alls 1.7
oof terrace 4.0
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