RELATION OF TOUGHNESS TEST VALUES TO FATIGUE CRACKING IN BRIDGES

Tension, Charpy, dynamic tear, C-399, and da/dN tests were conducted on three heats of A36 steel cut from a highway bridge which had been tested to failure in fatigue. Tension tests and E-399 tests were conducted at temperatures ranging from 70 deg F to -200 deg F while all other tests were conducted in the temperature range from 70 deg F to -50 deg F. During field testing, the girder from one heat appeared to be more susceptible to fatigue failure than the others, but there were no significant differences in either fracture toughness or laboratory crack growth rates. Crack growth rates decreased with decreasing temperature, and did not appear to be influenced by fracture toughness. The E-399 plain strain fracture toughness test was found to be unsuitable for A-36 steel. (FHWA)