This week, exactly 10 months after the collapse of the World Trade Centre, the Institution of Structural Engineers has published guidance that it hopes will mean a disaster of 11 September proportions will never happen again. Its recommendations on how to help buildings withstand a terrorist attack will affect existing buildings, as well as future designs, so what exactly are they?
- Structure
- Increase the capacity of a building's structure to limit damage so that it will remain stable even if a number of elements are damaged
- Do not locate structural elements fundamental to the building's survival near potential terrorist targets, such as fuel storage tanks
- Increase the capacity of the structural elements and their connections so that they can deform to absorb an impact. The collapse of many of the buildings at the World Trade Centre site has been attributed to a failure of structural connections
- Design the structure to resist the upward force of an explosion – the opposite direction to the building's normal loads
Fire protection
- Increase the capability of fire protection materials to remain in place following an impact or explosion
- Design buildings to survive a fire that consumes the building's entire contents
- Control the installation of IT and communication cabling through fire compartment walls
- Treat sprinklers as an addition to – and not a substitute for – passive fire protection
- Provide standby water supply systems for sprinklers
Escape management
- Design shafts containing escape routes so they do not become impassable to the building's occupants
- Position escape routes in different areas of the building
- Widen escape routes and stair widths to allow the simultaneous evacuation of people from a number of floors – or even the whole building
- Consider the use of lifts for evacuation
- Develop emergency response strategies for the management of occupants in different emergency scenarios
- Consider ways in which the building management team can be provided with sufficient information during an incident to enable them to decide on an appropriate plan of action. Consider how this plan will be communicated to buildings occupants and the emergency services
Cladding
- Use laminated glass with explosion-proof fixings or install anti-shatter film on existing buildings
Building Services
- Ensure unauthorised people cannot access air intakes and water tanks
- Design air distribution systems for rapid shut-down in the event of a fire or a biohazard
Unauthorised entry
- Provide security against unauthorised entry
- Prevent vehicles coming too close to the building
Postscript
Copies of the report are available from the Institution of Structural Engineers at www.istructe.org.uk.
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