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Spreading the word

Cover Story: After 9.11

Last year's terrorist attacks have given engineers the opportunity to educate the public about tall building design. Ysrael Seinuk tells Diarmaid Fleming how he reassures developers and their tenants.

Consultant Cantor Seinuk, owned by WSP, is one of New York's best known tall building designers, with a portfolio of projects across Manhattan. Principal Ysrael Seinuk says that while the engineering profession debates whether there should be changes to design codes, matters are moving more quickly on the ground. Building clients and occupiers are now asking questions they would not have asked a year ago.

'The general public has been educated by the media. Tenants have been educated. Big tenants are asking 'what has been done in this building to protect me?' and this is very widespread in New York. People are asking if stairs should be wider, for example, and people who have never before used the phrase are now talking about progressive collapse, meaning 'I don't want everything to come down at the same time', ' says Seinuk.

'And it's absolutely great that people have this kind of education. The questions are coming from prospective tenants and that has changed the way we design buildings over here - big buildings in particular - without the need of a code. I am not saying that we don't need a code change, but we are responding to the pressures of the marketplace and the marketplace is telling the developers.'

Seinuk agrees that suicide attackers present a huge new range of threats, but does not believe new codes are the answer.

'For new buildings, we now do a parallel document to an environmental impact assessment covering terrorist threat. We present to the client a risk analysis, and from this the level of threat has to be identified on many issues. And threats are not just structural - they could cover gas, biological attack, and redundancy of services for example, so that gas and electricity don't go into a building at the same point together. All of this is then presented to the design team, but it must be done on a building by building basis.

'Imposing regulations will have weaknesses and will lead to absurd situations. Two identical buildings could be in two different locations - one beside the sidewalk, the other in a development over 100m away from the street. How do you write a code for that?'

asks Seinuk.

He expects New York design codes to change to incorporate new requirements for progressive collapse, hardening of facades, fire safety requirements and evacuation of buildings.

'I hope that changes or recommendations do not become unnecessarily restrictive, and that there is room for the engineering and construction community to present alternative ideas to accomplish what everybody wants and at the same time maintain economy of construction, ' he says.

He says last year's attacks have begun a process of education for architects as well as engineers, and that this has yet to run its course. 'I've seen a number of designs in Europe on 20 or 30 storey buildings with architectural details which I think are inconsistent with trying to protect the building while trying to preserve the architectural feeling the architect wanted to give.'

Cantor Seinuk's UK experience has helped in incorporating blast resistant details at the outset. 'I am talking more about structure rather than facades, but often these are almost non-cost items. Another issue is window walls, buildings which are glass from top to bottom. Some of these older buildings can be protected by blending, changing from glass to stone.

Pictures from blasts in London show that after many bomb explosions, elements of facades such as brick or stone remained while the glass was gone.'

He says that incorporating some British design codes and practice on issues like progressive collapse would be welcome in New York codes, 'but like anything they are better or worse for certain issues'.

Seinuk says economic design is essential, and that British codes do not win on this count. 'Some of the UK codes are conservative. In the US the developer is present at all job meetings and they are much more aware of the unnecessary cost of conservatism. It's not a case of more engineering knowledge, just the experience of having done more ambitious buildings.

Sometimes you can say you are better because you have made most of the mistakes already, ' he says.

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