Generation of input motion for vibration test of lightly damped equipment

This paper describes methods for generating artificial motion applicable to seismic design analyses and vibration tests of plant equipment to prove seismic performance. A typical motion that satisfies the target response spectrum (TRS) is used as the input motion of the vibration test. The TRS is generally produced by enveloping various floor response spectra of the tested equipment so that the spectrum tends to have wide-band frequency components (WBFCs) reflecting various plant conditions. The WBFCs generally increase the maximum acceleration of the generated motion. Moreover, there are limits to shaking table performance, including applicable maximum acceleration, velocity, and displacement. These limits sometimes cause problems in generating the motion. This paper reviews some typical methods of generating artificial earthquake motion and their improvement to generate motion satisfying the WBFC spectrum for lightly damped equipment. Typical motions generated by the improved method have never been generated previously by conventional methods of generating artificial earthquakes. (author)