Seismic fragility analysis of a buried pipeline structure considering uncertainty of soil parameters

In this study, the seismic fragility analysis for a buried gas pipeline of API 5L X65 was performed considering the uncertainty of soil parameters. For this purpose, nonlinear time history analyses were carried out for the pipeline considering soil-pipeline interaction represented by beam on nonlinear Winkler foundation model. A total of 12 input ground motions were employed and four different analytical cases were considered to evaluate the effect of the uncertainty of soil parameters. The four cases proved that uncertainty of soil parameters needs to be taken into account for the assessment of the pipeline response. Using results of the nonlinear time history analyses, seismic fragility analyses were conducted in accordance with three damage states. Analytical predictions indicated that seismic fragility curves with the uncertainty of soil parameters exhibit higher failure probability than those without the uncertainty. It is thus concluded that the present study is promising for the exploration of the seismic fragility analysis considering the uncertainty of soil parameters.