Steel Buildings in Europe

Part 4: Detailed Design 4 – 54 loading about the minor axis over a width of h (in this case) also needs to be considered. The accidental loading should only be considered as acting in one direction at a time and there is no requirement to consider a diagonal loading case, i.e. at an angle to the major and minor axes. b eff 3 3 2 1 1 Key element 2 Portion of component that remains attached to key element after an incident 3 portions of component that are detached from key element during an incident Figure 6.8 Component attached to a key element (column on plan) Determining the width b eff is very subjective. An estimate of what will remain attached to the key element (during a loading of 34 kN/m 2 ) will obviously depend on what is attached and how it is fixed to the element. 6.5 Risk assessment Buildings which fall into consequence class 3 have to be assessed using risk assessment techniques. Annex B of EN 1991-1-7 [13] provides information on risk assessment and B.9 provides guidance specific to buildings. 6.6 Design summary  Determine the relevant consequence class from Appendix B.3 of EN 1990 [5] (Section 6.2)  Design members and connections to limit localised failure wherever possible. Columns will need to be designed as key elements where they are not continuous through to the basement; for example, where they finish on a transfer structure.  For design for localised failure, adopt the design strategy, limit of admissible damage and horizontal and vertical tying rules described in Section 6.3.  Where key elements have to be protected, the approaches outlined in Section 6.4 will have to be adopted.