Do skyscrapers have a future?

Posted On Tuesday, 04 June 2002 10:01 Published by eProp Commercial Property News
Rate this item
(0 votes)

The attacks of September 11 on the World Trade Center showed that New York's twin towers were well built. However, very tall buildings may have had their day

Jon MagnussonThe destruction of New York's twin towers by terrorists has put the future of very tall buildings in doubt.

If they are not safe enough to ensure the survival of people within them, do they have a future?

The fate of skyscrapers is a subject of much discussion, not just in North America, where they grace some of the world's most thrilling urban skylines, but in London, Shanghai and the Arabian Gulf.

Last week, the US Federal Emergency Management Agency released its preliminary findings into the collapse of the twin towers, raising issues for generations of engineers and architects about how tall buildings can be made safer.

Significantly, that report concludes the twin towers were extraordinarily well built. The steel-framed structures withstood the crashes, and, the report suggests, would have remained standing in the absence of the subsequent fires.

The report says: 'Remaining fuel (left over after the initial fireballs) flowed across the floors and down elevator and utility shafts, igniting intense fires throughout the upper portions of the buildings.'

It continues: 'As these fires spread, they further weakened the steel-framed structures, eventually leading to collapse.'

The collapse, FEMA notes, 'astonished most observers, including knowledgeable structural engineers'.

Among the report's recommendations are that spray-on fireproofing that can be dislodged by an explosion be avoided in the construction of buildings that might be subject to a terrorist attack.

It also suggests the towers were made more dangerous to occupiers by elements of design, including relatively thin encasements of evacuation routes.

However, the structure itself proved remarkably durable.

Jon Magnusson, chairman and chief executive at Skilling, Ward, Magnusson, Barkshire - a successor to the engineering company that built the twin towers, says that the steel ribs holding up the buildings were unusually rigorous.

The impact knocked out two-thirds of the steel ribs holding up the building. 'I don't know of any other building where you could take two-thirds of the columns out of one side and not immediately have it collapse.

'We had 20 structural engineers in the office watching it collapse. We couldn't believe it.'

Eerily, release of the report came shortly after a Piper light aircraft, flown by an experienced pilot described by his family as suicidal, hit the 30-storey landmark Pirelli Tower in central Milan.

Although far less destructive, the Milan crash suggests that structural engineers are entering a brave new world. Planners need to assume that their designs have to take into account anything that can be envisaged actually happening.

Reassuringly, people who should know best - insurers - insist that even now such events are likely to be very rare.

Robert Hartwig, chief economist of the Washington DC-based Insurance Information Institute says that, overall, aviation accidents have been on the decline.

Insurers had modelled worst-case scenarios before, but nothing on the scale of September 11.

Mr Hartwig says: 'One incident that had been modelled was the collision of two jumbo jets over a metropolitan area.'

But intent is quite another matter, he says, and insurers have had to return to the drawing board.

Does the height of a building tempt attackers?

Gail Fenske, professor of architecture at Rhode Island-based Roger Williams University, and an expert on skyscrapers, says the symbolism of tall buildings must not be overlooked.

'These buildings are symbols of wealth and modernity,' she notes.

This made them a tempting target.

Not all tall buildings, she says, are equally iconic or symbolic of Western power and wealth. Neither does height alone confer iconic status; the Pentagon is only four storeys high.

And ironically, the FEMA review of the World Trade Center collapse comes years after engineers erected the last US super-tall building. The only part of the world still putting up skyscrapers, Ms Fenske says, is Asia.

She says that skyscrapers no longer fit the new American business culture. 'Sure, Bill Gates will build himself a big house, but Microsoft is based in a low-rise campus.'

Nevertheless, the lessons from the collapse of the twin towers go beyond the US. While Europe does not aspire to super-tall buildings, structures taller than their surroundings are sprouting in Frankfurt, London and Paris.

And FEMA says there is much to be learned about what made the towers collapse. Some unanswered questions include why certain columns split several storeys up and why 7 World Trade Center - a 47-storey building next to the towers - collapsed as well.

And finally, FEMA says, much more could be done on improving emergency evacuation procedures from tall buildings.

But even if engineers can design a completely bomb-proof building, is that the standard to which structures should be built?

Nonsense, argues Mr Magnusson. 'That is the wrong place for society to put its resources. Even if we could construct bomb-proof buildings, what about the existing ones?

'And anyway, if you are talking about flying an airplane into a building, there's not much you can do except control the airplanes.'

Last modified on Monday, 19 May 2014 18:34

Most Popular

University of Fort Hare construction resumes

Jun 18, 2020
Construction of UFH Student Housing
Following two months of hard lockdown, the development of a 2 047-bed student village at…

SA property prospects as we look beyond COVID-19 lockdowns

Jun 11, 2020
John Loos FNB Property Economist
“The COVID-19 Crisis has changed the world a lot, perhaps less through introducing new…

Estate Agency Affairs Board to re-open its doors this month

Jun 13, 2020
Mamodupi Mohlala
The Estate Agency Affairs Board (EAAB) will re-open its Sandton, Johannesburg offices…

Grit to improve liquidity, save costs through proposed JSE de-listing

Jun 11, 2020
Bronwyn Corbett Grit
London Stock Exchange listed Grit announced its intention to de-list from the JSE.

Redefine’s European logistics platform set to expand its footprint in Poland

Jun 17, 2020
Andrew Konig CEO Redefine
JSE listed diversified real estate investment trust Redefine Properties (JSE: RDF) along…

Please publish modules in offcanvas position.