Structure: Approved Document A

REDUCING THE SEONSNITILVIITYN OEF T HVEE BURILSDINI GO TNO A3 DISPROPORTIONATE COLLAPSE IN THE EVENT OF AN ACCIDENT BS EN 1990:2002+A1:2005 with its UK National ‘Guidance on Robustness and Provision against Annex provides guidance on accidental Accidental Actions’, dated July 1999. design loading and accidental actions loading ‘Proposed Revised Guidance on meeting combination for ‘key elements’ and expressions Compliance with the requirements of Building 6.11a and 6.11b of that Standard are relevant. Regulation Part A3’. Revision of the Allott and Note: Annex A of BS EN 1991-1-7:2006 with Lomax proposals. Project Report No. 205966. its UK National Annex provides corresponding Both of the above documents are available on guidance for ‘key elements’. www.planningportal.gov.uk Load-bearing construction ‘Practical Guide to Structural Robustness and For the purposes of this Guidance the term ‘load- Disproportionate Collapse in Buildings’ dated bearing wall construction’ includes masonry October 2010. Published by The Institution of cross-wall construction and walls comprising Structural Engineers, London. close centred timber or lightweight steel section studs. Seismic design Alternative approach 5.5 Seismic design is not usually required for buildings classified by Table 11 as being 5.4 As an alternative to Table 11, for any in Consequence Classes 1, 2a and 2b. For building which does not fall into the classes listed buildings classified as Consequence Class 3 the under Table 11, or for which the consequences risk assessment should consider if there is any of collapse may warrant particular examination need to carry out seismic design, although such of the risks involved, performance may be a need is not an explicit requirement for these demonstrated using the recommendations given buildings. in the following Reports and Publication: Diagram 24 Area at risk of collapse in the event of an accident See para 5.1d Area at risk of collapse limited to 15% of the floor area of that storey or 100m2, whichever is the lesser, and does not extend further than the immediate adjacent storeys Approved Document A Structure O N L I N E V E R S I O N 45