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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.
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westerly movement of several inches of the pin at panel point 0. Since this is more movement than the clearance in the slotted hole can accommodate, there was an immediate abnormal loading of the chain bent post, producing a maximum bending moment on the reduced net section through the pin. Computations of the strength of this post under such loading conditions indicate that extreme fibers of this cross section would reach yield strength stress levels for a loading of about 20 kips on the pin. The actual separation of the post at this cross section shows very little evidence of yield except in the west splice plate and in the splice angles connected to the northeast corner. It is therefore believed that the rapid loading produced the observed cleavage fractures in some of the thicker sections such as the west channel flanges of this post at this early stage of the collapse. However, the post probably remained attached at this stage by at least the west splice plate and the east splice angles, because the loading was displacement limited. ## Step 2 Time = 1.2 seconds At this point in time, the final fracture of the upper limb of the C13 eye of eyebar No. 330 permitted the pin at C13N to rotate about a vertical axis, so that eyebar No. 33 slid off the south end of this pin. A burr on the northeast side of the pin hole in this eyebar was formed in the process (see Figure 9). In the model test, the eyebar corresponding to No. 33 was given a considerable impulse to the south at its C13 end as a result of this action, but did not come loose at joint C11. In the prototype structure, the retaining bolt at C11N was apparently broken, since the eyebar came completely free and was found on the ground with its C11N eye at about panel point 9 and its C13N eye just below the water edge. The elastic energy released in the failure of joint C13N could impart sufficient velocity to this eyebar to account for its westward movement, but it remains a mystery as to how it reached its final position in such a manner that portions of the deck system, one vehicle, and the north truss lay on top of it. It is possible that it fell in such a way that it punctured through the deck and then slid to its final position. The separation of joint C13N completely released the tension in the eyebar chain as far as joint U7N. Beyond this point, the relief of the tension was not complete, since the shortening of the eyebars caused them to pick up load as this shortening produced distortions and westward movement of the truss. The total elastic energy available in the eyebar chain from point U7N to the anchorage was about one half million foot pounds. If this had all been transferred into kinetic energy of motion of the side span, it would have produced a velocity of approximately 6 foot per second. However, neither the north truss nor the floor system was free to move without restraint, since they were attached to the south truss. The wind bracing system and dock slab insured that the two trusses moved very nearly the
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