Making Buildings Terror-proof

A week before the Sept. 11 terrorist attacks on the World Trade Center, structural engineers met at a conference in Frankfurt, Germany, and wondered aloud about how to build taller skyscrapers.

On Monday, they will join architects and other building experts in Chicago for a far more sober discussion: Will such high-profile symbols of power and prestige be built any time soon -- and, if so, what can be done to make them safer and more secure?

Never really read an architecture critic (if you don't count Tom Wolfe) before; never even knew of any outside of "The Fountainhead". But Kamin's a good head - he detests the "Glass Box" and does a good job of explaining why a building fits (or doesn't) into its surroundings. This piece is more informational than opinion; but he has a good reporter's sense for facts.

Sounds like the only thing they aren't including in new building plans is a SAM battery on the roof (hmmmmm). If they had economic probs filling offices before, all this additional expense prior to looking for tenants sure won't help. All in all, hard to picture society not building more big 'uns. It's just in our nature.

"Citing examples in Europe and Asia, the architects and engineers suggested everything from wider fire stairs that will enable people to get out of buildings more quickly to "refuge floors," heavily fireproofed floors where people can gather below a fire."

Terror proof is probably not possible, unless money is no object. I don't think any practical building could withstand 24000 gal of burning jet fuel. Wider staircases would help people escape, but in the WTC case a 'refuge floor' may have caused many more deaths when the floors above crashed down.

One thing that is sure to change is the way such buildings are built. In contrast to the nearly 30-year-old World Trade Center towers, which were chiefly supported by closely-spaced exterior steel columns that engineers call a "tube," the latest super-tall structures in Asia are held up by a more economical system consisting of a concrete core, several feet thick, and perimeter "super-columns" that provide additional stability. (The world's tallest buildings, the Petronas Twin Towers in Malaysia, use this system.)

Are those super-columns structurally able to withstand being hit by 100 ton missle? What would be the effect of losing some of them?

In most buildings, many structural components have zero redundancy. The loss of even one such component can damage the building severely. One of the things I found very impressive about the WTC was that the loss of many exterior columns through which the plane crashed did not cause the parts of the building above to immediately collapse. This is in stark contrast to most structures where the loss of any part of a column (except, perhaps, the very top) will cause an immediate failure that reaches all the way to the top since the beams that column normally supports are incapable of supporting their own weight without it, much less the new dead weight of the upper column itself.

BTW, one concept I was thinking of--probably a crazy idea, but who knows--would be to design a building with load-bearing interior walls whose configuration was different on different floors, with the intention of allowing for load redistribution in case of partial structural failure. Many of the walls would function as very tall trusses.

Essentially, the concept would be somewhat like that of a brick wall, where alternating rows of bricks are staggered. While the amount of material needed to support gravity loads would be greater than if a purely-vertical support system were used, the stagger arrangement could provide both horizontal stability and the ability to redistribute loads.

My thinking is that if you have a block wall where the blocks are stacked directly on top of each other (not staggered), the loss of a single brick will leave those above unsupported. By contrast, in a staggered block wall, the loss of a single brick will often have no effect on any other blocks (except perhaps to make the two blocks above a little wobbly); even the loss of several bricks will have only a localized effect.

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