Session: SE-06-01 The T.H. Liu Memorial Symposium on the Seismic Analysis and Design of Piping Systems-1

Paper Number: 121443

121443 - Design Application Method of Floor Response Spectrum Method Assisted by Time History Analysis for Multiply Supported Piping System 

The independent support motion (ISM) response spectrum method is currently used in seismic analysis to calculate the response of piping systems subjected to independent excitations at several points of a supporting structure. This approach leads to considerable overestimation when the maximum responses by multiple excitations are combined by the absolute sum rule, while this may result in underestimation when the maximum responses by the multiple excitations are combined by the square root of sum of squares rule. Then authors have developed an advanced method of the ISM approach named SATH (spectrum method assisted by time history analysis), which was presented in PVP2020. In the SATH method, both floor response spectra and time histories of floor acceleration are used as independent inputs of support excitations. The maximum responses by multiple excitations are combined using correlation coefficients calculated by taking into account each time history of modal response due to independent inputs of support excitations. When the SATH method is applied to actual design using broadened FRS, the structural frequency uncertainty corresponding to broadened FRS should be considered in the calculation of correlation coefficients. The applicability of the SATH method to the structural frequency uncertainty was presented in ICONE2020. Furthermore, when piping systems are subjected independent excitations at several points of a supporting structure, the response of piping systems can be considered to have two different components. One is due solely to the inertia of the mass (the dynamic component) and the other is due to the time-varying differential motion of the support point (the pseudo-static component). Here, the dynamic component consists of two parts: the damped-periodic response (dynamic response) and the residual rigid response (high frequency response). Then authors have improved the SATH method to cope with above three responses (dynamic response, high frequency response and pseudo-static response), which was presented in ASME PVP2023. As described above, since its presentation at ASME PVP 2020, the SATH method has been evaluated and improved several times and is now an appropriate method to use in design. In this paper, the entire procedure of the SATH method, which combines the dynamic response using broadened FRS, with the high-frequency response and the pseudo-static response, is described as an actual design method. In addition, the advantages of the SATH method in design are clarified by comparing the response by the SATH method with that by the conventional method (the uniform response spectrum analysis method and the independent support motion modal time history analysis method) for a three-dimensional piping system model subjected to independent excitations at several points of a supporting structure.

Presenting Author: Hiroaki Hioki MHI NS Engineering Co., Ltd.

Presenting Author Biography: - Graduated from Tokai University in March 2006
- Master’s degree (Physics) from University of Tsukuba in March 2008
- Joined MHI NS Engineering Co., Ltd. in August 2008. (MHI NS Engineering is a subsidiary of Mitsubishi heavy Industries.)
- Since joined in Mitsubishi heavy Industries group, I have been in charge of designing piping in nuclear power plants. Especially I have made a lot of effort at seismic stress analysis, thermal stress analysis, and so on.

Authors:

Ayaka Yoshida MHI NS Engineering Co., Ltd.
Yoshihiro Takayama MHI NS Engineering Co., Ltd.
Toshiyuki Tsushima MHI NS Engineering Co., Ltd.
Hiroaki Hioki MHI NS Engineering Co., Ltd.
Hiromichi Shudo Mitsubishi Heavy Industries, Ltd.