There are two seismic design methods for piping systems- time history analysis, which is a detailed method, and floor response spectrum analysis, which is a simplified method. In general, the floor response spectrum analysis method is used in design. However, since the floor response spectrum analysis method does not include phase information, it sometimes results in overestimation compared to the detailed time history analysis method. Then, as a different approach from previous analysis methods, Mitsubishi Heavy Industries, Ltd. has developed a floor response spectrum analysis method that uses correlation coefficients to combine the response by each seismic excitations wave to achieve almost the same accuracy as that by the time history analysis method. This analysis method has been publicized through presentations at academic conferences such as the Pressure Vessels & Piping Conference, and aims for application in actual plants.
