PROBING THE ANATOMY OF DISASTER

INVESTIGATION BY NATIONAL BUREAU OF STANDARDS TEAMS INTO THE FAILURE OF THE SILVER BRIDGE OVER THE OHIO RIVER IS REPORTED. ONE OF THE MAJOR FACTORS IN THE CATASTROPHE WAS A FRACTURED SUSPENSION BAR. A WORKING SCALE MODEL WAS MADE OF THE BRIDGE. AN EYEBAR SUSPENSION LINK ON THE OHIO SIDE OF THE RIVER WAS BELIEVED TO HAVE FAILED FIRST, TRIGGERING RAPID COLLAPSE OF ONE SECTION AFTER ANOTHER UNTIL BRIDGE, CARS AND TRAILER TRUCKS LAY STREWN BENEATH THE WATERS OR ALONG THE EMBANKMENTS. SCIENTISTS ANALYZED FRACTURE TOUGHNESS OF THE BRIDGE'S STEEL DETERMINING THE NATURE OF PRE-EXISTING CRACKS, MAKING FULL-SCALE TESTS ON SELECTED EYEBARS. FAILED WIRE OF THE HEAT-TREATED VARIETY WAS DISCOVERED IN THE MT. HOPE BAY (RHODE ISLAND) AND AMBASSADOR (DETROIT RIVER) BRIDGES. AN NBS FAILURE ANALYST SUPERVISED THE COLLECTION OF SAMPLES FROM THESE BRIDGES. THE CENTRAL CONCLUSION WAS THAT THE HEAT-TREATED WIRE HAD FAILED UNDER REPEATED ELASTIC BENDING STRESSES BECAUSE A PROVISION CALLING FOR PREFORMING OF EACH WIRE TO A LOOP CURVED LIKE THE ANCHOR SHOE HAD NOT BEEN PROPERLY CARRIED OUT. AT MT. HOPE BAY, THE HEAT-TREATED AND COLD-DRAWN WIRES HAD BEEN HOT-DIPPED GALVANIZED, WHEREAS COLD-DRAWN UNGALVANIZED WIRE HAD BEEN USED AT PORTSMOUTH. STUDY RESULTS CONFIRMED A PREVIOUS TENTATIVE CONCLUSION THAT SERVICE FAILURES OF THE PORTSMOUTH BRIDGE WIRES WERE DUE TO STRESS CORROSION, AND THE EXPERIMENTS DEMONSTRATED THE POSSIBLE MANNER IN WHICH THE CRACKS HAD FORMED. FAILURES IN WELDED STRUCTURES WERE STUDIED DURING WORLD WAR II AS AN ALARMING NUMBER OF SHIPS DEVELOPED CRACKS. NBS EMERGENCY SERVICE WAS GIVEN AFTER THE FAIRBANKS FLOOD OF 1967. A PRESIDENTIAL STUDY GROUP ON BRIDGE SAFETY WAS APPOINTED TO COORDINATE THE NATIONAL SURVEY OF BRIDGE INSPECTION METHODS. NBS HAS DEVELOPED CODES AND TESTS TO PROMOTE SAFETY AS TECHNOLOGY ATTAINS NEW HEIGHTS OF ACHIEVEMENT WHILE GENERATING UNPRECEDENTED RISKS.

  • Supplemental Notes:
    • Vol 10, No 7, PP 4-8, 8 PHOT
  • Authors:
    • Lichenstein, S
  • Publication Date: 1969-7

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00209078
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 12 1970 12:00AM