Developing Dynamic Digital Image Correlation Technique to Monitor Structural Damage of Old Buildings under External Excitation
Table 2
Test and analysis results of natural frequencies, damping ratio, and mode shape of steel test building with width of column = 380 mm under excitation of free vibration, Kobe earthquake record, and El Centro 1940 record.
(a)
Test and analysis results of free vibration traditional accelerometer
Items
1st mode
2nd mode
3rd mode
4th mode
5th mode
Natural frequency
1.0743
3.2036
5.1060
6.5896
7.5249
Damping ratio
0.5320
0.4916
0.4767
0.5022
0.4506
Mode shape
Base
0
0
0
0
0
1F
0.3155
0.7997
1
0.9547
0.5127
2F
0.5912
1
0.1928
−0.8875
−0.8923
3F
0.7940
0.4850
−0.9206
−0.1499
1
4F
0.9499
−0.3400
−0.4162
1
−0.8286
5F
1
−0.8691
0.7326
−0.6280
0.3532
Test and analysis results of free vibration proposed DIC method
Items
1st mode
2nd mode
3rd mode
4th mode
5th mode
Natural frequency
1.0551
3.1610
5.0600
6.5700
7.5240
Damping ratio
0.6270
0.6240
0.48931
0.4930
0.5860
Mode shape
Base
0
0
0
0
0
1F
0.3160
0.8390
1
0.9120
0.4421
2F
0.5700
1
0.1650
−0.9030
−0.8260
3F
0.7780
0.4770
−0.9550
−0.1430
1
4F
0.9250
−0.3740
−0.4140
1
−0.8513
5F
1
−0.9220
0.8060
−0.6520
0.4180
(b)
Test and analysis results of Kobe earthquake record traditional accelerometer
Items
1st mode
2nd mode
3rd mode
4th mode
5th mode
Natural frequency
1.0317
3.0969
5.0368
6.6412
7.6884
Damping ratio
0.6373
0.4574
4.6337
2.8685
5.5449
Mode shape
Base
0
0
0
0
0
1F
0.3773
0.9008
1
0.8386
0.7390
2F
0.6365
1
0.1596
−0.7806
−1
3F
0.8256
0.4324
−0.9755
−0.2302
0.8620
4F
0.9710
−0.3862
−0.3910
1
−0.5846
5F
1
−0.8833
0.7546
−0.6033
0.2264
Test and analysis results of Kobe earthquake record proposed DIC method
Items
1st mode
2nd mode
3rd mode
4th mode
5th mode
Natural frequency
1.6292
3.1732
5.1040
6.5572
7.4244
Damping ratio
0.5594
0.5271
3.952
2.9022
5.9642
Mode shape
Base
0
0
0
0
0
1F
0.3253
0.8001
0.9040
0.8371
0.7910
2F
0.5783
1
0.2295
−0.9281
−1
3F
0.7867
0.4750
−1
−0.2050
0.8232
4F
0.9320
−0.3711
−0.3954
1
−0.5547
5F
1
−0.9490
0.6543
−0.4450
0.2641
(c)
Test and analysis results of El Centro 1940 earthquake record traditional accelerometer
Items
1st mode
2nd mode
3rd mode
4th mode
5th mode
Natural frequency
1.0319
3.0975
5.0211
6.5905
7.6536
Damping ratio
0.6953
0.3928
0.7949
1.5966
3.6372
Mode shape
Base
0
0
0
0
0
1F
0.3777
0.9028
1
0.9123
0.5205
2F
0.6374
1
0.0868
−0.9088
−0.9208
3F
0.8274
0.4325
−0.9507
−0.1363
1
4F
0.9721
−0.3865
−0.3792
1
−0.8075
5F
1
−0.8820
0.7432
−0.6229
0.3449
Test and analysis results of El Centro 1940 earthquake record proposed DIC method
