Full-scale laboratory tests on 1,270 mm (50 in.) long, 305 mm (12 in.) diameter steel pipes were carried out to investigate their postwrinkling behavior when subjected to monotonic and cyclic bending loads. Under monotonically increasing bending loads and deformations, the test specimens exhibited the ability to undergo significant plastic deformation and did not fail in fracture (leak or rupture in the pipe wall). However, when subjected to cyclic elastic-plastic strain reversals due to cyclic bending deformations, fracture developed at the wrinkle. This study indicated that the current pipeline design method using wrinkle limit strain is conservative. The paper presents test procedures, postwrinkling behavior, and fracture limit strain values obtained from four full-scale tests.
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