Influence of Excitation on Dynamic System Identification for a Multi-Span Reinforced Concrete Bridge

Table 8

Uncertainty in modal properties using impact excitation with noise in output.

Analysis description	Natural frequency (Hz)						Mode shape MAC value
	Mode 1		Mode 2		Mode 3
	Avg.	𝜎	Avg.	𝜎	Avg.	𝜎	Mode 1	Mode 2	Mode 3
Eigenvalue	2.480	—	4.024	—	5.695	—
No noise	2.472	—	4.006	—	5.609	—	0.9957	0.9986	0.9569
1% noise	2.483	0.012	4.153	0.162	5.668	0.109	0.9956	0.489	0.5202
2% noise	2.479	0.019	4.130	0.192	5.754	0.118	0.9955	0.0319	0.4387
5% noise	2.491	0.016	—	—	6.140	0.280	0.9955	—	0.9787