New York Times article on WTC truss study

NYC 9/11 Public Portal Document

Forensic Engineering

STUDY ABSOLVES TWIN TOWER TRUSSES, FIREPROOFING ed by the planes’ impacts and flying debris confirm that columns with intact fireproof­ ing did not succumb to the jet­ fuel-triggered fire. The report also says, of the fireproofing ‘ knocked off the steel, that “no fireproofing is designed to withstand such devastating .) impacts.” ; Levy echoes preliminary / reports. “The buildings were • well-designed, rugged and withstood a tremendous ; impact,” he says. “The fact that they did not collapse on the i planes' impacts saved tens of thousands of lives." Questions brought into the limelight by Sept, 11 include FIRST DOWN Plane took out comer of whether there is a better way to core, which hastened collapse. fight fires in tall buildings, says tf»e engineer. “It's always been a and 2/Axis Corp. problem,” says Levy. Silverstein’s insurers claim the col- t>» ' »«yi Aiother issue is whether less- lapse of the south tower, Two WTC, ren- SMOKE PROOF Engineers say smoke patterns are frangible fireproofing should dered the north tower, One WTC, unsal- evldence that columns failed first, not floors. be considered for steel struc- vageable even before it collapsed. If they Cures considered vulnerable to prevail, Silverstein would receive only THE MOST COMPREHENSn’E STUDY YET blasts and attacks. Experts might also >3.5 billion (ENR 10/7 p. 11). on the destruction of the World Trade reconsider location of fire stairs and the The insurers commissioned their own Center concludes that columns robbed strengthening of the core, says Levy. But engineering study, written by Exponent of fireproofing failed first—not floor he cautions, “You can never anticipate Failure Analysis Associates Inc., Los trusses-—when the twin 110-story towers exacdy what the threat is going to be.” Angeles. Also released, die report dis­ collapsed after being hit by ter­ ■MM Regarding building materials, agrees with the Weidlinger findings, but rorist plane attacks on Sept. 11, 1 1 ‘■'7 says: “Concrete is not fool- mostly on points relating to the insur­ 2001. The proof is in the smoke proof either.” ance batde. Engineers from Wiss, Jan­

11 that emanated from the burning The Weidlinger-led study was ney, Elstner and Associates Inc., North- towers before the collapses. 3 commissioned by Silverstein “There is no doubt left about W Properties Inc., the New York 2 •J the sequence of failure,” says City-based leaseholder of the Matthys P. Levy, chairman of Wei- FAd World Trade nMFWTT i dlinger Associates Inc., the New levy York City-based engineer that led ■ — COUAPSfSEOUENCE the study. a $7-bjllion insur- s “Failure of the floors...was shown not ance claim. The to have had any significant role in the research team also ( initiation of the collapses,” says the included LZA Tech- report Levy describes the floor truss sys­ nology/Thornton- tem as “not unsubstantial,” acting more Tomasetti Group; I like a membrane than a one-way system. ARUPFire; Hughes I 'There was nothing wrong with it” he Associates Inc.; Safir- g says. If the floor trusses had collapsed Rosetti; Hillman I first there would have been a mass of Environmen tai I smoke as opposed to differentiated Group; RWDI; W. 'fflwfiniii mi r ti ■ Bit Hg.iiiH.flasf in 5 smoke, floor by floor, he adds. Gene Corley, who led The report also exonerates the steel’s the ASCE-FEMA I sprayed-on fireproofing. Computer WTC study; Profes- I models that identify the columns affect- sor Sean Ahearn; SECOND DOWN North tower lasted longer due to Impact site.

ENR/November 4. 200’2

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