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This is the final highway accident report (NTSB-HAR-71-1) from the National Transportation Safety Board, adopted in December 1970. It covers the collapse of the U.S. 35 bridge between Point Pleasant, West Virginia, and Kanauga, Ohio, on December 15, 1967, which killed 46 people. The Board found that the cause was a cleavage fracture in eyebar 330 at joint C13N. That fracture grew from a flaw produced over 40 years by stress corrosion and corrosion fatigue, in a spot that could not be seen or found by inspection.
“The Advance”2 pages
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At about this time (see Reference 14), the bracing attached to the top of the north leg of the Ohio tower separated. The combined effect of the northward and eastward loadings of the south leg due to the eastward movement of the north leg (about two feet at the top at this time), and the now unbraced eccentric load exerted by the south chain on the top of this leg, produced a bending and a fracture of the south leg just above the portal bracing. This initiated a northerly movement of the south chain, the fractured upper portion of the leg pivoting just above the portal bracing. The north side of the main span continued in essentially free fall, but the portions east of about panel point 30 now developed a secondary mechanism of load support. A deflection of approximately five feet at panel point 30 eliminated the clearance which existed at the expansion joint in the deck at the West Virginia tower. This permitted the north truss and the chain connected from panel point 35 to the top of the West Virginia tower to act as a "tied cantilever." As displacements continued, this cantilever action gradually picked up load, and at the same time lifted the north edge of the West Virginia side span because of the restoration of tension in the chain and then its increase beyond the normal value due to the dynamic application of load. The computed static tension in the chain at the top of the tower for such action is 1909 kips, which is very close to the normal tension at this point (dead load plus collapse live load). ## Step 4 Time = 1.7 seconds At about this time, the top of the south leg of the Ohio tower was some 15 feet north of its original position but had undergone only very small eastward movement. This action exerted a northward component on all elements in the Ohio side span and the main span through the south truss. It also produced a bending moment around the east-west axis in the south Ohio chain bent post at a relatively slow rate of loading. Meanwhile, the north truss continued to fall but was pushed to the north because of lateral loadings transmitted to it through the floor system which was still attached to the south truss. The estimated deflections of the north truss at this step are as follows: Panel Point 7...8 ft., downward Portions between Panel Points 8 and 13...10-12 ft., downward Main Span Portions West of Panel Point 30...8 ft.; downward West Virginia Side Span Panel Point 51...3 ft., upward ## Step 5 Time = 2.0 seconds At this time (1.0 seconds since the final separation of the chain at C13N) the center of the main span had fallen approximately 16 feet at
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