Long Term Monitoring of Donghai Bridge in China

Long-Term Monitoring of
Donghai Bridge in China
Limin Sun
Co-researchers:
Dr. Danhui Dan, Dr. Zhi Sun and Mr. Zhihua Min
Dept. of Bridge Engineering, Tongji
Univ, China
AHMED ABDEL-GHAFFAR INTERNATIONAL SYMPOSIUM
USC, 19th Sept 2008
Outline
• SHM for long span bridges in China
• SHMS of Donghai Bridge
- Donghai bridge and its SHMS
- Monitoring data (about 1 year) - what we get
- Data analysis - how to use data
• Concluding remarks
SHMS for Bridges in China
• More than 50 large bridges have installed a SHMS in
China since 1999.
• The primary objectives of SHMS:
– To obtain comprehensive knowledge on structural
performance, which is further used for assessing the
structural safety, durability and serviceability
– To validate design assumptions and design loads, and to
provide data for consummating the design code
– To provide support for maintenance during operation
• The cost of a SHMS generally take about 0.5-2.0% of
the total construction cost of a bridge.
Donghai Bridge
•
•
Donghai bridge is a linkage
connecting Shanghai and Yangshan
Island deep water Port. The linkage
is about 32 km long and consists of
2 cable stayed bridges and a large
number of spans of continuous and
simply supported bridges.
The bridges have been completed
and opened to traffics in 2005. The
health monitoring system was
completed in Oct., 2006.
Shanghai
Port
SHMS for Donghai Bridge
• Donghai Bridge is the only way linking the port to Shanghai.
It is a very important structure.
• Donghai Bridge is the first large scale cross-sea bridge
project in China and lies on soft clay so the durability
against ocean environment and the un-uniform settlement
of foundation are seriously concerned.
• The bridge carries heavy container trucks, so the fatigue of
steel deck is seriously concerned.
• The structural health monitoring system for Donghai Bridge
(SHMSDH) was designed to automatically collect the data
of structural deformation, force, stress and so on through
the sensors embedded in or installed on surface of the
structure.
Monitored spans
Outline of monitored spans of
Donghai Bridge
Luchao Port
Bottomland area
(70-50m continuous
girder spans)
Sub-navigation channel Bridge
(70+120+120+70m continuous
girder spans)
5X60m continuous
girder spans
Main-navigation channel Bridge
(420m cable-stayed bridge)
Kezhushan Bridge
(332m cable-stayed bridge)
Sub-navigation channel Bridge
(80+140+140+80m continuous
girder spans)
Open air station
to corruption
5X70m continuous
girder spans
Yangshan Port
Sub-navigation channel Bridge
(90+160+160+90m continuous
beam spans)
Monitored items
• Environment of bridge site including temperature,
wind speed, earthquake, wave and scour;
• Static and dynamic response of bridge including
deformations of towers of cable-stayed bridges,
deflections of continuous girders,
un-uniform settlements of foundations,
displacements of dampers and expension joints,
strains of girders,
vibration of girders and towers,
tensions of stay cables, ;
• Durability of structure including fatigue of steel
structures and chloride corrosion of concrete.
Primary sensor technologies used
• FBG sensors for strains and temperatures
• GPS for monitoring deformations
• Fatigue sensor for fatigue of bridge girders
• 478 sensors in total
(169 for main-navigation channel bridge)
Modules of SHMSDH
Sensor system
Wind
Temperature
Strain
Acceleration
Deflection
Settlement
Cable tension
GPS
Clinometer
Fatigue
Displacement
Portable
inspection &
maintainence
system
Data processing and control system
Data acquisition and
transmission system
Signal process
Amplifying
Filtering
A/D D/A conversion
Data
transmission
Data Receiving
Control signal
sending
Data processing
Pre-process
Re-process
Storage
Data acquisition
Sampling
Storage
Pre-treatment
Sampling control
Data
presentation
Original data
Processed data
Deformation of
bridge
State of system
Others
Online evaluation
Alarming
Grading
Monthly report
Data transmission
Transmission
Receiving of control
Offline structural evaluation system
Normal operation
Items monitored
Safety, durability,
& serviceability
Total evaluation
After accident
Items monitored
Safety
Total evaluation
Modular of structural evaluation
LAN
Evaluation systems
• On-line evaluation
The on-line evaluation system is an automatic system.
- The system can analyze the data than to judge preliminarily the
safety of structure.
- The system is able to automatically make a decision of whether it is
need to alarm the management authority and to immediately start the
off-line evaluation system.
• Off-line evaluation
The off-line evaluation system will process some advantaged analysis,
such as structural static analysis, mode analysis, correlated analysis
between the bridge behaviors and environmental factors and so on.
The system needs massive structural analysis and judgments by
experts then gives an comprehensive evaluation of structural condition.
May 13, 2005
May 21, 2005
July 6, 2005
Oct 30,2005
Main features of SHMSDH
Accessible via internet
The real-time signal data collecting system
Monitoring data – for evaluation under extreme loads
• Typhoon
• Earthquake
• Explosion
• Ship collision
Ship collision
0.5
Modal damping ratio
(Hz)
0.55
Frequency
0.025
mode1 before
mode1 after
mode2 before
mode2 aftere
0.45
mode4 before
mode4 after
0.02
0.015
0.01
0.005
0.4
0
500
1000
0
1500
0
Time (min)
2007-01-01 00:00:00
2007-01-02 01:35:00
(a) 船撞前后模态频率的比较
A comparison between before and after collision
1
A comparison between before and after collision
2007-01-02
00:50:00~2007-01-02
01:35:00
0.985
0.98
MAC(2,2) before
MAC(2,2) after
0.99
MAC
MAC
0.99
0.98
2007-01-02
00:50:00~2007-01-02
01:35:00
0.97
0.96
0.975
0.95
0
500
2007-01-01 00:00:00
1000
1500
2000
2500
3000
Time (min)
2007-01-03 02:35:00
(a) 船撞前后MAC(1,1)的比较
0
500
2007-01-01 00:00:00
1000
1000
1500
2000
2500
3000
Time (min)
2007-01-03 02:35:00
(b) 船撞前后MAC(2,2)的比较
1500
(min)
2007-01-02 00:50:00
2007-01-03 02:35:00
(b) 船撞前后模态阻尼比的比较
1
MAC(1,1) before
MAC(1,1) after
0.995
500
Time
2007-01-02 00:50:00
2007-01-03 02:35:00
2007-01-01 00:00:00
2007-01-02 01:35:00
Sichuan Earthquake
Data analysis – prepare for damage identification ?
Is it possible to separate?
Total response of structure measured
Response due to
environment change
Response due to
structural damage
Example of Monitoring Data Analysis of
Donghai Bridge
Outline of monitored spans of
Donghai Bridge
Luchao Port
Bottomland area
(70-50m continuous
girder spans)
Sub-navigation channel Bridge
(70+120+120+70m continuous
girder spans)
5X60m continuous
girder spans
Main-navigation channel Bridge
(420m cable-stayed bridge)
Kezhushan Bridge
(332m cable-stayed bridge)
Sub-navigation channel Bridge
(80+140+140+80m continuous
girder spans)
Open air station
to corruption
5X70m continuous
girder spans
Yangshan Port
Sub-navigation channel Bridge
(90+160+160+90m continuous
beam spans)
73m
830m
420m
132m
132m
169 sensors
Type of sensor
Thermometer
Thermometer
Thermometer
Anemometer
Weather station
GPS
FBG strain sensor
FBG strain sensor
Accelerometer
Accelerometer
Fatigue sensor
Extensometer
Cable force sensor
Displacement sensor
Quantity
1
24
20
1
1
3
36
12
19
8
24
4
8
2
Measurement
air temperature(At)
steel temperature(St)
concrete temperature(Ct)
wind speed/direction(Ane)
wind speed/direction, humidity(Aws)
displacement
steel dynamic strain
concrete dynamic strain
acceleration
acceleration
displacement
cable force(Cf)
displacement
Location
Deck
Deck
Deck/Tower
Tower
Deck
Tower/Deck
Deck
Tower/Deck
Deck
Tower
Deck
Expansion joint
Cable
Deck
73m
Environmental factors - Temperature
40
30
0
temperature ( C)
Air Temp.
20
10
0
0
60
120
180
240
300
360
time (d)
40
40
Steel Temp.
temperature ( C)
30
30
0
0
temperature ( C)
Concrete Temp.
20
10
20
10
0
0
0
60
120
180
time (d)
240
300
360
0
60
120
180
time (d)
240
300
360
Environmental factors - Wind
100
humdity (%)
80
60
40
20
0
0
60
120
180
time (d)
• Wind speed
• Humidity
240
300
360
Environmental factors - Traffic
4
rms (gal)
3
2
1
0
0
60
120
180
240
300
time (d)
Vertical acc.
RMS
>> equivalent traffic load
360
Modal Parameters
1st Modal freq.
2nd Modal freq.
0.646
0.644
frequency (Hz)
0.642
0.640
0.638
0.636
0.634
0.632
0.630
0
60
120
180
240
300
time (d)
3rd Modal freq.
4th Modal freq.
360
3rd modal freq. vs. Temp.
PSD of Freq. and
Temp.
Correlation between Freq. and
Temp.
Displ. at expansion joint and
Temp.
Concluding remarks
•
More than 50 large bridges have installed a SHMS in China. Generally,
the cost of a SHMS will take about 0.5-2.0% of the total of construction
of a bridge.
•
SHM for Donghai Bridge was introduced. The response data during
typhoon, earthquake, explosion and ship collision were automatically
collected for rapid evaluation.
•
It is possible to distinguish the structural response induced by
temperature change (wind? traffic?) from the entire response. This may
improve the feasibility of damage identification.
Thanks!