New Seismic Design Criteria of Piping Systems in High-Pressure Gas Facilities

Abstract

After the Great Hyogoken-nanbu Earthquake (1995), the Seismic Design Code for High-Pressure Gas Facilities of Japan was amended. This amended code requires two-step seismic assessments, that is, the evaluation of the Level 1 Required Seismic Performance for Level 1 earthquakes and that of the Level 2 Required Seismic Performance for Level 2 earthquakes. Seismic design of piping systems is newly included within the scope of the code. For Level 2 earthquakes, possible ground displacement due to liquefaction is taken into account. The evaluation method of the Level 1 Required Seismic Performance is specified in the amended code and that of the Level 2 Required Seismic Performance is proposed in the guideline. The evaluation of the former is based on elastic design and that of the latter on elastoplastic design. The propriety of the design criteria of piping systems with respect to ground displacement was confirmed by large deformation tests. In this paper, seismic design criteria of piping systems in the amended code and the evaluation method of the Level 2 Required Seismic Performance proposed in the guideline are introduced, and the results of the large deformation tests are reported.