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1、Structural Investigation Group Chairman Factual ReportPage 9NATIONAL TRANSPORTATION SAFETY BOARDOffice of Research and EngineeringMaterials Laboratory DivisionWashington, D.C. 20594month/day/year DRAFTSTRUCTURES GROUP CHAIRMAN FACTUAL REPORTReport No. 08-015 Print Date 2008/2/26 23:01:00 A.ACCIDENTT
2、ype of Accident:Bridge CollapseDate:August 1, 2007Location:Interstate 35W Bridge across the Mississippi River, Minneapolis, MinnesotaNTSB No.:HWY07MH024Investigator in Charge:Gary Van EttenB.STRUCTUAL INVESTIGATION GROUPJames F. Wildey II, Group ChairmanJoseph Epperson, Group MemberChief, Materials
3、Laboratory, NTSBSenior Metallurgist, NTSB490 LEnfant Plaza East, SW 490 LEnfant Plaza East, SWWashington, DC 20594Washington, DC 20594Joseph Hartmann, Group MemberEdward Lutgen, Group MemberBridge Engineer, FHWAAsst. Construction Engineer, MnDOT6300 Georgetown Pike3485 Hadley Ave.McLean, VA 22101Oak
4、dale, MN 55128The Structures Investigation Group was greatly assisted by the following individuals: Dustin Thomas of the Minnesota Department of Transportation (MnDOT), Frank Zakar, Carl Schultheisz, and Derek Nash of the NTSB, Mike Koob, Jonathan McGormley, Mark Chauvin, Jennifer Dimig, Jon Lewis,
5、Kristin Duchateau, Brady Shelburmun, Steve Michael, and Wade Clarke of Wiss Janney Elstner, Wesley Weir, Bill Clark, Scott Darling and Steve Shaup of Tran Systems, and Benjamin Graybeal, Bill Wright, and Justin Ocel of the Federal Highway Administration. MnDOT also provided extensive administrative
6、and logistics support. C.ACCIDENT SYNOPSISOn Wednesday, August 1, 2007 at about 6:05 pm (CDT) the 35W Interstate Highway Bridge over the Mississippi River, in Minneapolis, Minnesota, experienced a failure in the supporting structure. Approximately 1,000 feet of the 1,900-foot-long bridge collapsed w
7、ith approximately 456 feet of the center span falling about 108 feet into the 15-foot-deep river. There were approximately 88 vehicles on the portion of the bridge that collapsed with 15 vehicles falling into the water. Roadway construction was occurring on the center span of the bridge and four of
8、the eight lanes were closed for re-paving when the bridge collapsed. The bridge was last inspected by MnDOT on June 15, 2006.The remainder of this report has the following major sections.D.GENERAL DESCRIPTION OF THE BRIDGE AND NOMENCLATUREE. RECOVERY OF THE STRUCTUREF. TESTING AND MEASUREMENTSFigure
9、sFigure 1. Elevation of I-35W Bridge (looking west)Figure 2. Typical deck truss section near Pier 6 or 7Figure 3. Typical section through steel multi-girder approach spansFigure 4. Typical section through voided concreteFigure 5. Elevation, East Main TrussFigure 6. Elevation, West Main TrussFigure 7
10、. Typical Floor Truss and Sway FrameFigure 8. Plan View of Lower Lateral BracesFigure 9. Plan View of Upper Lateral BracesAppendix 1.Detailed Description of Structural Members of the Deck TrussAppendix 2.Survey Results and Description of Piers and Bearings, Deck TrussAppendix 3.Corrosion Measurement
11、s, Nodes L11E and L11W, Deck TrussAppendix 4.Description of Components in the South Approach SpansAppendix 5.Description of Components in the North Approach SpansD.GENERAL DESCRIPTION OF THE BRIDGE AND NOMENCLATUREThe I-35W Bridge over the Mississippi River was a 14-span, 13-pier structure with a to
12、tal length of 1,907feet, as shown in figure 1. MnDOT designated this as Bridge 9340. The piers and spans were numbered from south to north. Spans 1 through 4 and a portion of span 5 are referred to as the south approach spans and were steel multi-beam spans having a length of 416feet and a slight ho
13、rizontal curvature. A portion of span 5, all of spans 6, 7, 8, and a portion of span 9 was consisted of a variable depth steel deck truss having a total length of 1,064feet. A portion of span 9 and spans 10 through 14 are referred to as the north approach spans and consisted of a 3-span continuous w
14、elded steel multi-beam module and a 3-span continuous voided concrete slab module having a length of 427 feet. The north end of the south approach spans and the south end of the north approach spans were cantilevered over their respective piers and were supported on the ends of the center deck truss
15、 portion of the bridge.The deck truss structure extended from south of pier 5 to north of pier 8 and included a portion of span 5, the entirety of spans 6 through 8 and a portion of span 9. As shown in figure 1, the deck truss portion of the bridge consisted of 28 panels, each 38 feet long for a total length of 1,064 feet. The center span of the deck truss (span 7, that crosses which crossed the river) consisted of 12 panels at 38feet each for a total length of 456feet. The north and south portions of the deck truss each consisted of 8 panels at 38feet each T
