Structural Safety Analysis Based on Seismic Service Conditions for Butterfly Valves in a Nuclear Power Plant

Table 1

Comparison of natural frequencies obtained using initial and modified FE-models.

	1st mode	2nd mode	3rd mode
Natural frequency obtained from the experimental modal test (Hz)	69.3	72.2	219.7
Natural frequency obtained by using the initial FE-model (Hz)	92.7 (25%)	96.4 (25%)	236.6 (7.7%)
Natural frequency obtained by using the modified FE-model (Hz)	68.9 (0.5%)	72.3 (0.1%)	226.6 (3%)

() means % errors (abs.) to natural frequencies obtained from experimental modal test.