Structural Health Monitoring of Precast Concrete Box Girders Using Selected Vibration-Based Damage Detection Methods

Table 4

Error in predicted damage location by each method, listed as a fraction of measurement point spacing, when two and three modes were used in combination with 7 measurement points.

Method	2 modes				3 modes
	Max. error	Avg. error	Stand. dev.	% ambig*	Max. error	Avg. error	Stand. dev.	% ambig*
CMS	0.35	0.15	0.08	2.5	0.25	0.14	0.07	5
DI	0.95	0.33	0.24	2.5	0.65	0.26	0.18	22.5
MCF	0.45	0.18	0.13	0	0.45	0.16	0.11	7.5

*indicates the percentage of the 40 cases that produced a second peak that was either at least 75% of the magnitude of the highest peak, or nearer to the damage location, including near support damage cases.