Piping systems in nuclear power plants are designed to withstand loads such as self-weight, internal pressure, thermal loads, and seismic loads. Considering the damage modes caused by each load is important to design piping systems withstanding various loads. Loads can be classified into restoring force-controlled loads, which cause primary stresses that lead to ductile fracture or plastic collapse, and deformation-controlled loads, which cause secondary stresses that lead to forced deformation. While self-weight and internal pressure are considered restoring force-controlled loads, and thermal loads are considered deformation-controlled loads, the classification of seismic loads has not been fully elucidated. We have proposed that seismic loads acting on piping systems can be classified into force-controlled and deformation-controlled loads using a maximum force-deformation diagram of nonlinear single-degree-of-freedom systems. In this study, to demonstrate the applicability of this method to actual piping systems, we confirmed that the maximum force-deformation diagram of a piping system shows similar trends to that of a bilinear single-degree-of-freedom system. Therefore, it was confirmed that the classification of seismic loads acting on piping systems using the maximum force-deformation diagram for a bilinear single-degree-of-freedom system is effective.
SHIMAZU et al. (Wed,) studied this question.