抄録
Buried pipelines may be deformed due to earthquakes and also corrode despite corrosion control measures such as protective coatings and cathodic protection. In such cases, it is necessary to ensure the integrity of the corroded pipelines against earthquakes. This study developed a method to evaluate the earthquake resistance of corroded pipelines subjected to seismic motions. Pipes were subjected to artificial local metal loss and to axial cyclic loading tests to clarify the cyclic deformation behavior until buckling occurs under seismic motion. As the cyclic loading progressed, displacement shifted to the compression side due to the formation of a bulge. Finally, the pipe buckled after several cycles. To evaluate the earthquake resistance of different pipelines, with varying degrees of local metal loss, a finite-element analysis method was developed that simulates the cyclic deformation behavior. A combination of kinematic and isotropic hardening components was used to model the material properties. These components were obtained from small specimen tests that consisted of a monotonic tensile test and a low cycle fatigue test under specific strain amplitude. This method enabled the successful prediction of the cyclic deformation behavior, including the number of cycles required for the buckling of pipes with varying degrees of metal loss.
