Structural Monitoring of the Akashi Kaikyo...
Transcript of Structural Monitoring of the Akashi Kaikyo...
Structural Monitoring of the Akashi Kaikyo Bridge
Kiyohiro Imai
Honshu Shikoku Bridge Expressway Co. Ltd.
Japan and Honshu Shikoku Bridges2
Pacific Ocean
Hokkaido
Honshu
Kyushu
Japan Sea
Seto-Inland sea
Osaka
Tokyo
Shikoku
N
Naruto
SakaideImabari
Kojima
Onomichi
Kanmon Tunnel
Kanmon Bridge
Seikan Tunnel
Nagoya
Kobe
Okayama
Kurashiki
Akashi Kaikyo Br.
Ohnaruto Br.
Wakayama
Sumoto
Kobe
Osaka
Kansai International Airport
Awaji Island
NarutoTokushima
Sakaide
Takamatsu
Matsuyama
Imabari
Hiroshima
Onomichi
Kobe Naruto Route
Kojima Sakaide Route
Iwakurojima Br.
Hitsuishijima Br.
Shimotsui-Seto Br.
Minami Bisan-Seto Br.
Kita Bisan-Seto Br.
Kurushima Kaikyo Br.
Hakata Ohshima Br.
Tatara Br.
Ikuchi Br.
Innoshima Br.
Ohmishima Br.
Onomichi Imabari Route
Shin Onomichi Br.
Sanyo Expressway
Chugoku Expressway
Matsuyama
Expressway
Tokushima
Expressway
Kochi
Prefectural Capital
Honshu
Shikoku
Yoshima Br.
Outline of the Honshu Shikoku Bridges3
Honshu Shikoku Bridges contribute to the national highway network between Honshu and Shikoku Islands
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AKASHI KAIKYO BR.
OHNARUTO BR.
SHIMOTSUI SETO BR.
HITSUISHIJIMA BR.
IWAKUROJIMA BR.
KITA BISAN-SETO BR.
MINAMI BISAN-SETO BR.
SHIN-ONOMICHI BR.
INNOSHIMA BR.
IKUCHI BR.
TATARA BR.
OHSHIMA BR.1ST KURUSHIMA KAIKYO BR.
2ND KURUSHIMA KAIKYO BR.
3RD KURUSHIMA KAIKYO BR.
KOJIMA-SAKAIDE
ONOMICHI-IMABARI
KOBE-NARUTO
OHMISHIMA BR.
CALENDAR YEAR
YOSHIMA BR.
BRIDGEBRIDGE
TYPE
SUSPENSION
SUSPENSION
SUSPENSIONCABLE-STAYED
TRUSS
SPAN LENGTH
(m)(SIDE+CENTER+SIDE)
960+1991+960
330+876+330
230+940+230
185+420+185
185+420+185
175+245+165
SUSPENSION
SUSPENSION
274+990+274
274+1100+274
SUSPENSION
ARCH
SUSPENSION
SUSPENSION
SUSPENSION
SUSPENSION
85+215+85
250+770+250
150+490+150
270+890+320
297
140+560+140
140+600+170
250+1020+245
260+1030+280
CABLE-STAYED
CABLE-STAYED
CABLE-STAYED
CABLE-STAYED
Construction history of Honshu Shikoku Bridges4
Kobe EQ.
Akashi-Kaikyo Bridge5
Main Tower
Stiffening Girder
Side View
3 span, 2 hinged stiffening girder systemNumber of lanes: 6Opened to traffic in 1998
1A 2P 3P 4A
960 9601991
85 80 78 80(unit:m)
T.P.+297.3
46.5
General View of the Akashi-Kaikyo Bridge6
35.5m
T.P.+81.0
T.P.+10.5
Akashi Kaikyo Bridge just after the Earthquake(January 23, 1995)
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0.8m
0.4m
N
Effects of Kobe earthquake onthe Akashi Kaikyo Bridge
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Kobe
Awaji Island
Ground movement
Relative deformation of bridge
1990
1990.8m
3910
3911.1m
960.3m960.0m
960960
1A 2P 3P 4A
Kobe Awaji Island
Honshu Island
Dynamic Monitoring and Precise Inspection9
in order to know change of the state with time
Categories Monitoring
or Inspection
Object parts Items measured Intervals
Structural
PreciseInspection Whole bridge
Shape of the whole bridge
5 yearsDisplacement of foundations
Suspender rope tension
DynamicMonitoring Whole bridge
Wind velocity and direction, displacement, velocity,acceleration
always
Material
PreciseInspection
Paint for steel members
Film thickness, glossiness, adhesion
About 5 years
Monitoring Main cablesTemperature and humidity inside of main cables and in spray saddle rooms
always
Precise Inspection
Concrete structures
Chloride ion concentration, neutralization depth 5 years
Others PreciseInspection
Tower foundation
Seabed scour condition around Tower foundation
5 years or more
Outline of Dynamic Monitoring 10
Long-span Bridges in the Honshu-Shikoku Bridges・10 Suspension bridges, 5 Cable-stayed Bridges,1 Truss bridge, 1 Arch bridge (span length > 200m)
Objectives・Evaluation of bridge behavior during extraordinary event・Evaluation of bridge soundness after extraordinary event
Sensors arrangement・Wind characteristics are observed
on the Akashi-Kaikyo Bridge and the Tatara Bridge.・Seismic motions are observed at 2 locations on each route.・Bridge behavior is observed on the representative bridges.
①Akashi-Kaikyo Bridge, ②Ohnaruto Bridge, ③Minami Bisan-Seto Bridge, ④Tatara Bridge, ⑤Kurushima Kaikyo Bridges
Arrangement of Monitorng Sensors on the Akashi Kaikyo Br.11
1A 2P 3P 4A
Earthquake recorder : Accelerometer
: Velocity Gauge: Wind Speed Gauge : Displacement Gauge
: GPS
960m 960m1991m
Kobe Awaji
100km200km300km
Japan Sea
8.0 9.0M
7.5 8.0M
7.0 7.5M
6.5 7.0M
6.0 6.5M
Pacific Ocean
Earthquakes around the Akashi Kaikyo Bridge12
Natural period, T (sec)
Acc
eler
atio
n r
esp
on
se s
pec
tru
m (
gal
)
0.1 0.2 0.3 0.5 0.7 1 2 3
1000
700
500
300
200
100
70
50
30
20
(0.206sec, 800gal) h = 0.05
Standard
acceleration
response
spectrumM=8.5
Distance=150km
TR=150 years
Acceleration response spectrum for the design 13
Epicenter
Awaji Island
M6.3 Earthquake on April 13, 2013
Location of Seismometer
Kobe side
Observation of Seismic Motions14
Akashi Kaikyo Bridge
0.1
1
10
100
1000
0.01 0.1 1 10
Acc
eler
atio
n r
esp
on
se s
pec
tru
m (
gal)
Time (sec.)
h=0.05Longitudinal direction
Transverse direction
Original design
Transverse velocity at the center of the middle span
Acceleration Response Spectrum15
-30m
-50m
-70m
-70m
-50m
-40m
-50m
-20m
-80m
-100m
-80m-60m
-40m
-60m
-110m
Maiko
Awaji Island
KOBE
The Akashi Kaikyo Bridge
1A
2P
3P4A
Akashi Kaikyo waterway
Wind observation tower
80m
Wind Observation Site16
1965 1970 1975 1980 1985
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20
30
40
50
60
70
Win
d v
eloci
ty (
m/s
)
: Gust wind velocity
: Mean wind velocity
(10 min. average)
65.0m/s
52.2m/s
Year
Typhoon No.20
Typhoon No.23
Lack of data
Wind Observation Data17
Wind
Full-model Wind Tunnel Test (S=1/100)18
VerticalStabilizer
V=60 m/s (at girder)
Transverse direction
Win
d v
elo
city
(m/s
)W
ind
dir
ecti
on
(d
egr
ees)
Observed Wind Data of September 22, 1998 (Typhoon 9807)19
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:00
14
:00
15
:00
16
:00
E
N
S
W
13:00
14:2016:00
North-east
South-east
Horizontal Displacement
Wind
1A 2P 3P 4A
Arrangement of GPS sensors20
Wind Speed
Time history (Second)
Win
d v
elo
city
(m
/s)
32.0 m/s
Time (Second)
Girder Displacement at the Middle of the Center Span
Observed Horizontal Displacement on the Akashi Kaikyo Bridge21
Gir
der
Dis
pla
cem
ent
(cm
)
Comparison of Observed and Analytical Data22
Observed
displacement (m)
Analytical results (m)
Case 1 Case 2
Average displacement
① 5.17 5.43 5.43
Dynamic displacement
② 0.78 2.62 0.68
Total displacement
(①+②) 5.95 8.05 6.11
Note : Average wind speed was 32.0 m/sCase 1 was using designed power spectrum and spatial correlationCase 2 was using observed power spectrum and spatial correlation
Horizontal Girder Displacement at the Middle of the Center Span
0
2
4
6
8
10
0 10 20 30 40Average wind speed (m/s)
Ho
rizo
nta
l gir
der
dis
pla
cem
ent
at t
he
mid
dle
of
the
ce
nte
r sp
an(m
)
Designed average displacement
Designed dynamic displacement
Observed average displacement
Observed dynamic displacement
Designed total displacement
Observed total displacement
Relation between Girder Dispalcementand Wind Velocity
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Dry air flow between galvanized wires
Dehumidifier and blower Air injection cover
Injection mouth
Exhaust opening
Dehumidifier and blower
Supply pipe
Girder
Tower
Cable
Dry-air Injection System developed by HSBA24
■ Keep relative humidity in the cables less than 60%, andthe cable can be protected from corrosion.
■ Dry-air injection system was introduced to keep relativehumidity less than 40% in the cables.
腐食の限界湿度
Relative humidity (%)
Co
rro
sio
n v
olu
me
of
Zn g
alva
niz
ing
(g/m
2)
Attached salt
60
Corrosion of a main cable
Monitoring of Dry-air Injection System25
(Just after a start of operation)
Year, month
40%
0
20
40
60
80
100
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98
.3
Rel
ativ
e h
um
idit
y (%
)
Outer air Inside cable
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97
.11
19
98
.7
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98
.11
19
99
.3
19
99
.7
19
99
.11
20
00
.3
20
00
.7
Monitoring Data of Humidity in Cables26
Temporally suspended
(During normal operation)
40%
0
20
40
60
80
100
Rel
ativ
e h
um
idit
y (%
)
Year, month
20
04
.5
20
04
.9
20
05
.1
20
05
.5
20
05
.9
20
06
.1
20
06
.5
20
06
.9
20
07
.1
20
07
.5
20
07
.9
Outer air Inside cable
Monitoring Data of Humidity in Cables27
Cable Opening Inspection in 2008 and 20189 and 20 years after Completion
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February, 2008 (9 year)
No rust
Inspectoin Window
Wedge
November, 2018 (20 years)
Inspection Window
No rust くさび
Conclusion
◼ Dynamic monitoring has been conducted on major Honshu Shikoku Bridges
◼ It was confirmed that original design of the bridges is appropriate and proved to be conservative.
◼ Main Cables have been protected against corrosion by the Dry-air Injection System.
◼ It was confirmed that main cables are in proper condition.
◼ In order to improve the Dry-air injection system, more efficient operation has been currently investigated and introduced. (Reduction of operation units, reduction of air pressure, installation of pre-cooling units, etc.)
Conclusion29
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Thank you very muchfor your attentions !
Akashi Kaikyo Bridge