抄録
Piping systems supported by multiple support structures are excited by different floor response for each support position. Seismic response of piping systems can be calculated accurately by independent time history analysis (ITHA) in considering multiple excitations. On the other hand, the uniform response spectrum analysis (URSA) is commonly used in seismic design of piping systems of nuclear power plant owing to its advantages of simplicity and conservativeness. The floor response spectrum at the center of gravity of piping systems is generally applied in the URSA. In order to check the accuracy of URSA with the floor response spectrum at the center of gravity of piping systems, a comparison of ITHA and URSA was carried out. The actual piping systems of nuclear power plant spreading largely in vertical direction was selected as analysis object model so that the difference of seismic excitation for each support structure is relatively large. In the seismic response analyses, horizontal floor response of two directions and vertical direction was input. As a result of comparison, piping stress calculated by URSA is larger than that of ITHA at most of piping nodes including the point where the maximum stress is generated. It was confirmed that piping stress can be evaluated conservatively by URSA with the floor response spectrum at the center of gravity of piping systems.
