The central core of Barclays’ new 33-storey head office has been beefed up to enable it to withstand terror attacks. Walls have been thickened by 100 mm to 400 mm and stairs in the central core have been widened to allow the building’s occupants to shelter in the core in the event of an emergency. Next to the central core are two smaller satellite concrete cores. These will eventually house fire escape stairs, offering extra protection to tenants.
The Barclays skyscraper is the second tower to be designed to withstand terrorist attacks. A 57-storey tower designed by Skidmore Owings & Merrill is being built to replace Seven World Trade Centre, which caught fire and collapsed late on September 11.
The building’s enhanced robust structure has been designed by structural engineer Cantor Seinuk to ensure the building doesn’t suffer from progressive collapse. Cantor Seinuk, a tall buildings specialist, also designed the Barclays tower’s structure.
These two towers are likely to become blueprints for future skyscrapers. Developers will now demand the latest safety innovations in their buildings to reassure prospective tenants. How far developers will be prepared to go in making their buildings terrorist-proof will depend on the costs of safety enhancement, and the size of the office space eaten up by beefed up structures.
Many of the safety and security measures adopted by Barclays have been developed by working groups set up in the aftermath of September 11. The most important safety guide published so far is Safety in tall buildings and other buildings with large occupancy, which was published by an international working group convened by The Institution of Structural Engineers.
This guide makes recommendations on: progressive collapse; passive and active fire protection; escape, its management and the emergency services; and other issues, including safety of cladding, building services and security against unauthorised entry. The group includes experts from the UK, America, Australia and Hong Kong and includes Gene Corley, the American structural engineer responsible for investigating the collapse of the towers.
While the Safety in Tall Buildings working group looked at structural collapse, Arup’s extreme events taskforce examined the implications of a chemical or biological attack. A report Chemical or Biological Terrorist Attacks on Buildings, includes recommendations on emergency evacuation and protecting water supplies and ventilation.
The American based Council on Tall Buildings and Urban Habitat has also published two safety guides since September 11. Building Safety Assessment Guidebook and Building Safety Enhancement Guidebook, offering advice for building owners and designers. The CTBUH, in conjunction with the International Council on Research and Innovation in Building and Construction, will also be holding a conference on Tall Building Strategies from May 8-10 in Kuala Lumper.
It is important that developers don’t ignore the research on tall buildings and skimp on safety features. By following the example of Barclays and designing terror-proof buildings the public’s confidence in tall buildings should be to some extent restored. Eventually Building Regulations should force up standards but in the meantime buildings that fail to make the grade could be shunned by prospective tenants.
Lower insurance premiums should also act as an incentive for companies to move into terror-proof buildings. Barclays will no doubt be pointing this out to prospective tenants of their new building, as they are letting out a third of the 93,000 m sq of office space.