Civil Engineering Reference
In-Depth Information
11.4.3 Lateral Damping of Bridges Using Ground Motion Data
The damping ratios of the bridges subjected to different levels of shaking were calculated by using the EFDD and the SSI
method provided by Software Artemis Extractor [
6
]. The results are reported in Table
11.3
as function of the maximum
acceleration recorded at the deck, and displayed in Figs.
11.7
and
11.8
. For levels of shaking smaller than 0.06 g the EFDD
method estimates damping ratios from 1.14 % to 2.21 %. For the same range of amplitudes the SSI method estimates ratios
Table 11.3
Lateral damping ratios obtained using ground motion data
Freq.
(Hz)
EFDD
Damp(%
ξ
)
SSI
Damp(%
ξ
)
Bridge name
Deck acceleration (g)
AlvisoOverpassK
0.04
1.661
2.131
4.713
AlvisoOverpassL
0.05
2.568
2.437
4.317
LakeCrowley
0.06
5.342
0.356
0.75
LakeCrowley
0.04
5.239
2.213
2.94
LakeCrowley
0.02
5.621
1.148
2.171
Highway101-156Overpass
0.02
1.598
1.464
5.81
Highway101-156Overpass
0.09
2.093
1.19
2.408
Highway101-156Overpass
0.02
2.414
1.5
1.614
BarrelSprings
0.02
2.844
1.977
4.783
BarrelSprings
0.09
3.003
2.7
3.05
ViaCalifornia
0.02
2.688
1.356
3.98
ViaCalifornia
0.09
2.675
2.675
2.275
ViaCalifornia
0.06
2.623
1.753
3.35
Meloland
0.04
3.023
2.01
2.811
3
AlvisoOverpassK
2.5
LakeCrowley
2
Highway101-
156Overpass
BarrelSprings
1.5
1
ViaCalifornia
0.5
Meloland
0
Fig. 11.7
Damping as
function of max acceleration
on deck estimated with EFDD
0.00
0.02
0.04
0.06
0.08
0.10
Acceleration (g)
7
AlvisoOverpassK
6
LakeCrowley
5
Highway101-
156Overpass
BarrelSprings
4
3
2
ViaCalifornia
1
Meloland
0
Fig. 11.8
Damping as
function of max acceleration
on deck estimated with SSI
0.00
0.02
0.04
0.06
0.08
0.10
Acceleration (g)
