FRACTURE TOUGHNESS OF STRUCTURAL GRADE BRIDGE STEELS PART II

This project was performed to determine how brittle fracture resistances of bridge steels vary with loading rate. Critical stress intensities of four ASTM A36 and A441 steels were measured at 332 deg F at impact loading rates with instrumented Charpy impact tests and at bridge and slow loading rates with 2-inch compact tension tests performed with a cyclic minor load superimposed on the test load. Fractures initiated without precrack growth, near yield at secant load ratios (Pmax/P sub O) of 1.06 or less, or above yield with lateral contractions of 50 mils (2.5%) or less on extension. Fractures extended without arrests. The upward "shift" of impact test temperatures compensating for reduced fracture resistances at impact loading matched temperature differences between precracked impact and slow bend curves at the lowest inflection point. Shifts were 30% to 63% of delta T = 215 - 1.5 Yield (ksi) and 45% to 99% of the 70 deg AASHTO shift. One steel passing AASHTO requirements for use 0 deg F fractured brittley at 32 deg F. Methods were developed to estimate the minimum critical stress intensity for ductile fracture, and the impact test values and temperatures requires to assure this property. These indicate impact test requirements utilizing a fixed or solely yield based "temperature shift" are invalid. (FHWA)

• Corporate Authors:

  California Department of Transportation

  Transportation Laboratory
  5900 Folsom Boulevard
  Sacramento, CA  United States  95819
• Authors:
  • Kendrick, C B
  • Smith, R D
  • Crozier, W F
• Publication Date: 1980-6

Media Info

• Pagination: 166 p.

Subject/Index Terms

• TRT Terms: Crash tests; Fracture mechanics; Load tests; Loads; Metal bridges; Steel bridges; Structural steel; Temperature
• Uncontrolled Terms: Loading rate
• Old TRIS Terms: Resistance
• Subject Areas: Bridges and other structures; Geotechnology; Highways; Materials; Research; I34: Steels and Metals;

Filing Info

• Accession Number: 00325952
• Record Type: Publication
• Report/Paper Numbers: FHWA-CA-TL-80-11 Final Rpt., FCP 45F2-152
• Contract Numbers: D-4-116
• Files: TRIS, STATEDOT
• Created Date: Mar 12 1981 12:00AM