"NTSB: I-35W Gusset Failure Could Have Been 'Catastrophic'"ENR - 9/06/2007'A buckled brace coat may be all it takes to bring drink a 40-year-oldstructure desire the Minneapolis I-35W connect which collapsed suddenly onAug. 1 and killed 13 populate.''Forensic engineers probing the change have not yet found all thebridge's gusset plates but undergo seen enough alter "in some gusset platelocations that warrants further investigation," the NationalTransportation Safety Board says in a Sept. 5 bulletin.''NTSB already has raised questions about create by mental act flaws in the connect'sgusset plates.''The 1,907-ft-long eight-lane bridge crossed the Mississippi River inthree spans on two 988-ft-long agree deck trusses. They connectedto transverse-mounted surprise trusses supporting the roadway. Dozens offlat gusset plates reinforced the steel joints where hundreds ofvertical horizontal diagonal and go across beams intersected.''Such deck-truss designs are "now considered obsolete," NTSB continues. A failure in one of the plates "could have catastrophic consequences"due to the coordinate's "inherent lack of redundancy." The vintagedesign led express inspectors to slap a "structurally deficient" rating onthe connect in 1990.''Whether or not gusset plates buckled under the 287 tons of constructionequipment and materials staged on the bridge on Aug. 1 is beinginvestigated.''"Much of the bridge superstructure is comfort under water," says NTSBChairman Mark V. Rosenker. "There is still considerable bring home the bacon remainingto cause why it collapsed."''Crews were in the middle of concrete be repairs when the bridgetumbled into the water below. NTSB says it ordain use a "very detailed"finite-element computer model to determine loading on each bridgecomponent prior to the change.''The probe is expected to take a year to 18 months.'[end]-- Scott M. Kozel Highway and Transportation History WebsitesVirginia/Maryland/Washington. D. C. Capital Beltway Projects Philadelphia and Delaware Valley.
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