Freedom Tower Mockup Passes Extreme Tests

Of course you can’t fly a plane into it during a test, but that probably won’t ever happen again:

One World Trade Center has not yet emerged from below ground, but its facade has already survived earthquakes, hurricanes and an explosion that shook the earth a quarter-mile away.

In recent months, two full-size mock-ups of a few floors of the glass and aluminum facade have been built and tested. One is outside Los Angeles, in Ontario, Calif. The other was at a site in central New Mexico that can be reached only over dirt roads in four-wheel-drive vehicles.

At 1,368 feet, with 23 acres of glass-clad surface area, 1 World Trade Center will be subject to tremendous natural forces. The building, also known as the Freedom Tower (at a symbolic 1,776 feet, when its mast is counted), will be the tallest in New York City and as the skyscraping phoenix on the site of ground zero, it may be the target of terrorist attacks, too.

The Port Authority of New York and New Jersey, which is building 1 World Trade Center, and Skidmore, Owings & Merrill, which designed it, said both mock-ups performed well. The facade, called a curtain wall, is being made by Benson Industries of Portland, Ore. The engineering firm Weidlinger Associates is the consultant in blast-resistant design.

“Physical testing is a confirmation that curtain-wall contractors are in fact meeting performance requirements,” said Carl Galioto, a Skidmore partner. “Full fabrication of the curtain wall cannot begin until the mock-up specimen passes these tests.”

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The first mock-up was subjected to a blast test in Socorro, N.M., at the Energetic Materials Research and Testing Center, a division of the New Mexico Institute of Mining and Technology. Because details might arm a prospective attacker — providing information like how much force the curtain wall is designed to withstand — officials would say almost nothing about the test of this mock-up.

“The simple answer is, yes, it passed,” said John McCullough, the project executive for the Port Authority.