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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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test program consisted of chemical analyses; metallurgical examinations; tension tests for yield, tensile strength, and ductility; and Charpy impact tests to assess notch-toughness. The general results of these investigations are given in Appendix B. In general, the material met the specifications for A7-24 steel, the detailed requirements of which are also indicated in Appendix B. The "15 foot pound transition temperature" for pieces from the various elements and with indicated orientation with respect to rolling were as follows:
U7N gusset plate (longitudinal specimen)...80°F
U7N gusset plate (transverse specimen)...92°F
North chain bent post (longitudinal specimen)... $ 7 4^{\circ} \mathrm{F} $
The major conclusions of this work are as follows:
(1) This material meets the requirements for A7-24 steel called for in the specifications for the Point Pleasant Bridge.
(2) Variations of properties are noted for material taken from different thickness members, but these were all within the specification range.
(3) This material was operating well below its "15 foot pound transition temperature" at the time of collapse of the structure (at $ 3 0^{\circ} \mathrm{F} $ ) such that fractures could be propagated at low energy levels compared to those required for propagation in the ductile range. The 15 foot pound transition temperatures for material of different thicknesses were all in the upper end of the range of service temperatures at which the structure was required to perform, although the transition temperature for the chain bent post material was lower than that of the thicker gusset plate material. This was attributed to the finer grain size associated with the thinner material and higher manganese content of the post material in comparison to the gusset plate material.
e. Part 5 of the National Bureau of Standards report series (Reference 21) discusses the examination of a sample of hanger material designated as 12C, which was obtained from the upper end of the hanger at panel point 17 in the north truss and which had a cleavage fracture surface on its upper end. The cleavage fracture extended across the 1-1/4 inch x 6 inch hanger bar at an angle of about 75 degrees to the longitudinal axis of the hanger. Chemical and mechanical tests on Document, cited by the archive. The PDF is mirrored here; the original link is above. The text was read from the page images by GLM-OCR; expect the odd misread word. 202 pages are in the text index: search them above, or from the library's search.