Vibration Control of Nuclear Power Plant Piping System Using Stockbridge Damper under Earthquakes

Table 3

Dynamic properties of the piping system.

Mode	Period (sec)	Frequency (Hz)	⁢Modal participating mass ratio			Generalized mass (kg)
			1st	0.575	1.741		0.0003	0.3800	0.0642	182
2nd	0.471	2.125	0.0000	0.0641	0.4100	170
3rd	0.190	5.254	0.0020	0.0185	0.0002	166
4th	0.173	5.779	0.0007	0.0001	0.0005	—
5th	0.102	9.806	0.0280	0.0091	0.0000	—
6th	0.086	11.563	0.0000	0.0003	0.0183	—
7th	0.074	13.426	0.0128	0.1200	0.0004	—
8th	0.059	16.869	0.3000	0.0096	0.0211	—