ANALYTICAL STUDY ON SEISMIC RESPONSE OF PIPING UNDER MULTIPLE SUPPORT EXCITATIONS

Conventional response spectrum analysis is used for piping seismic design in Japan. When piping is supported by restraints and structures fixed on multiple buildings or floors, the envelope of the response spectra of all supporting points is typically applied for the piping under multiple excitations. The local vibration mode of long piping is difficult to excite by the far input from the vibrating part, so the analysis will overestimate the response. Considering each input from each building or floor can estimate more reasonable seismic response of the piping. The researches about seismic response analysis by multiple input excitations have been performed since 1960s and the analysis methods are used for piping design in the United State. There are a few experimental researches to verify the validity of the analysis method by multiple excitations. So an excitation test by multiple excitations planned to verify the validity of the application. This current study was performed as a preliminary investigation for the excitation test and it was to obtain the seismic response of a piping model by multiple excitations. Several kinds of analysis methods are compared and the characteristics of them are discussed.