Detection of Earthquake-Induced Damage in a Framed Structure Using a Finite Element Model Updating Procedure

Table 4

Comparison of measured and analytical natural frequencies.

Stage	Mode	Measured Freq. (Hz)	RS model		FS model
			Freq. (Hz)	Percent error	Freq. (Hz)	Percent error
PGA 0.12 g	1st	3.78	3.78	0.0%	3.78	0.0%
	2nd	12.65	12.73	0.6%	12.68	0.2%
	3rd	24.85	24.82	−0.1%	24.99	0.6%
	4th	40.80	40.60	−0.5%	40.13	−1.6%
PGA 0.20 g	1st	3.00	2.90	−3.3%	3.13	4.3%
	2nd	11.06	11.02	−0.4%	11.17	1.0%
	3rd	22.42	22.61	0.8%	22.14	−1.2%
	4th	39.73	37.98	−4.4%	36.00	−9.4%
PGA 0.30 g	1st	1.90	1.83	−3.7%	2.03	6.8%
	2nd	8.49	7.84	−7.7%	8.79	3.5%
	3rd	19.64	17.73	−9.7%	17.80	−9.4%
	4th	34.67	31.67	−8.7%	29.38	−15.3%
PGA 0.40 g	1st	1.59	1.68	5.7%	1.82	14.5%
	2nd	8.16	7.27	−10.9%	8.04	−1.5%
	3rd	18.55	16.80	−9.4%	16.10	−13.2%
	4th	33.40	30.55	−8.5%	26.45	−20.8%
PGA 0.50 g	1st	1.24	1.32	6.5%	1.45	16.9%
	2nd	7.57	6.31	−16.6%	6.98	−7.8%
	3rd	17.49	15.65	−10.5%	14.90	−14.8%
	4th	32.32	29.41	−9.0%	24.78	−23.3%