Identification of Sudden Stiffness Change in the Acceleration Response of a Nonlinear Hysteretic Structure

Table 4

The relative errors between identified parameters and actual model parameters.

Case	Seismic excitation	Relative error (%)
		k1	k2	ζ1	ζ2	Y	α	β	γ	n
S1	(a) El-Centro earthquake	0.19	0.09	7.00	3.00	3.24	10.00	10.00	4.00	3.00
	(b) Kobe earthquake	0.15	0.09	6.00	8.50	5.29	0.00	12.00	14.00	2.50
	(c) Northridge earthquake	0.36	0.06	2.00	1.00	10.22	0.00	22.00	22.00	1.50
	Average values	0.23	0.08	5.00	4.17	6.25	3.33	14.67	13.33	2.33
S2	(a) El-Centro earthquake	0.50	0.18	4.50	8.00	1.93	10.00	6.00	—	0.50
	(b) Kobe earthquake	0.01	0.10	6.00	9.00	0.78	0.00	2.00	—	2.00
	(c) Northridge earthquake	1.15	0.44	19.00	4.50	0.42	0.00	8.00	—	3.50
	Average values	0.55	0.24	9.83	7.17	1.04	3.33	5.33	—	2.00
S3	(a) El-Centro earthquake	0.21	0.06	1.50	12.00	0.67	—	4.00	—	0.50
	(b) Kobe earthquake	0.48	0.07	7.50	8.00	1.36	—	4.00	—	3.50
	(c) Northridge earthquake	0.08	0.36	14.00	2.50	0.64	—	8.00	—	1.50
	Average values	0.26	0.16	7.67	7.50	0.89	—	5.33	—	1.83
S4	(a) El-Centro earthquake	0.41	0.09	4.00	8.50	6.18	10.00	10.00	22.00	—
	(b) Kobe earthquake	0.10	0.09	8.00	8.00	5.82	0.00	12.00	16.00	—
	(c) Northridge earthquake	0.29	0.01	8.00	0.50	2.73	0.00	4.00	12.00	—
	Average values	0.27	0.06	6.67	5.67	4.91	3.33	8.67	16.67	—