An Experimental Study of the Feasibility of Identifying the Impact Damages of Reinforced Concrete Piers Using a Modal Frequency Method

Table 6

Identification of the pier damages using the modal frequencies of the test columns.

Specimen no.	Impact time	Impact velocity (m/s)	Impact energy (J)	First-order frequency (Hz)		Damage factor
				Before impact	After impact
Z16-1	1	1.181	836.8566	27.337	23.538	0.258626
	2	1.376	1136.026	23.538	22.78	0.305606
	3	1.589	1514.953	22.78	21.194	0.398931
	4	1.717	1768.853	21.194	19.7	0.480685
Z20-1	1	1.047	657.7254	23.116	21.242	0.207939
	2	1.354	1099.99	21.242	21.017	0.224629
	3	1.603	1541.765	21.017	20.985	0.226989
	4	1.806	1956.982	20.985	19.544	0.329506
Z16-2	1	1.378	1139.33	24.365	20.453	0.219390
	2	1.336	1070.938	20.453	20.062	0.295337
	3	1.316	1039.114	20.062	19.271	0.322022
	4	1.316	1039.114	19.271	18.565	0.374430
Z16-3	1	1.496	1342.81	22.817	19.362	0.279916
	2	1.496	1342.81	19.362	19.118	0.297950
	3	1.471	1298.305	19.118	18.395	0.350046
	4	1.549	1439.641	18.395	17.47	0.413769
Z20-2	1	1.587	1511.141	27.383	20.472	0.441069
	2	1.587	1511.141	20.472	19.926	0.470485
	3	1.587	1511.141	19.926	19.332	0.501585
	4	1.587	1511.141	19.332	19.09	0.513985