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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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from ductile to brittle fracture behavior at about $ 0^{\circ} \mathrm{F} $ . for the high strain rates associated with the Charpy test, which are on the order of $ 1 0^{3} $ microinches/inch per second.
The dramatic change in the fracture behavior at essentially static load rates in the slow bend tests are indicated by the dotted curve in the diagram. For these strain rates, which are estimated at approximately $ 1 0^{-3} $ microinches/inch per second, the transition from ductile to brittle behavior occurs at much lower temperatures than those in the dynamic Charpy test.
The Charpy impact data were also used to construct the conventional transition temperature curve by plotting energy at fracture against temperature. This technique of data interpretation resulted in an estimate of $ 3 6^{\circ} \mathrm{F} $ for the "15 Ft. Lb. transition temperature." Further discussion of these results is deferred until they are compared with the results from other laboratories in the analysis section of this report.
## 3. Investigations at U. S. Steel Applied Research Laboratory
Tests and investigations at the United States Steel Corporation's Applied Research Laboratory at Monroeville, Pennsylvania, were conducted partly to obtain independent checks on materials properties, metallurgical and fractographic results, and also to study certain special problems. This work was conducted without charge to the Government by U. S. Steel, functioning as a Party in Interest in the investigation.
a. The early test results of this laboratory on the properties of the eyebar and truss steel, as submitted to the working group on February 14, 1969, and supplemented on March 3, 1969, are included in Appendix B. These include tests to determine chemical composition, tensile properties, hardness variations through the thickness, and Charpy impact test properties for the eyebar steel; and chemical composition, tensile and Charpy impact properties of a sample of the A7-24 steel. The samples of eyebar steel were taken from the C9 head of eyebar C9-C11 north chain, north bar (designated C9) and the C11 head of eyebar C11-C13 north chain, north bar, (designated sample CO), which was also known as eyebar No. 330. Supplemental results of tests on another sample removed from the C13 head of eyebar No. 330, submitted in May 1969, are also included in Appendix B.
These results, in general, corroborate those obtained by the NBS laboratory. Minor differences are discussed in the analysis section of this report. They established that there were no significant differences in chemical composition or mechanical properties between eyebar No. 330 and other eyebars in the structure. The C13 head of eyebar No. 330 showed slightly lower carbon, manganese and sulfur contents, but insignificant differences in resulting mechanical properties. Hardness profiles across the thickness and from pinhole surface to interior of the 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.