2011 International Conference on Intelligent Building and Management
Proc .of CSIT vol.5 (2011) © (2011) IACSIT Press, Singapore
Structural Health Monitoring of Concrete Bridges in Rudbar-Manjil
Region in Iran
Mehdi Mohammadpour Lima1, Sobhan.A Alipour Limaei 2
1
2
Master of Science in Earthquake Engineering, lecturer in Islamic Azad University of Bandar-e-Anzali
Master of Science in Geotechnical Engineering, Road and Transportation Office of Guilan Province
Abstract.
Iran is located in a seismic prone region and in every year, several earthquakes happen that cause severe
damages. Guilan province is located in the north of Iran. High seismic activity of this region, especially
Rudbar and Manjil city needed to regular inspection of infrastructure and bridges. Structural health
monitoring is an engineering tool that is used for control the changing of condition that gives good
information for management, decision and revise codes. In this paper structural health monitoring of 6 mega
concrete bridges in Rudbar region are studied and existing condition of main component are assessed then
some solutions suggested to solve the problems in these bridges.
Keywords: Bridge, Health Monitoring, visual Inspection, Seismic, Rehabilitation
1. Introduction
Lifelines and infrastructure have an important role in every country and several thousand dollars have
been paid to maintenance and rehabilitation of infrastructures annually. Bridges, as an infrastructure that
connect the cities are important from political, economical and social point of view. Guilan is a province on
border of Caspian Sea, in the north of Iran, with a high residential density and it has a moderate climate.
Rudbar is one of important city that connect the north of Iran, Guilan province to the capital and the other
part of Iran. Therefore, there are some important bridges in this region that sustain heavy track loads and
passing rate of cars over bridges is significantly increased in recent years. This is because of construction
new high way and free way between Guilan province and Qazvin province. Rasht-Qazvin highway that
passes through Rudbar is an important free way that facilitates the transmission of goods to industrial towns
and capital. In recent years, construction rate of bridges grows up and using new methods are going to be
usual in bridges. Construction of long bridges over wide rivers with different geotechnical situation, local
condition such as rivers, liquefaction, and landslide has its own challenges. Transportation and goods trade to
neighbourhood provinces made Guilan's roads and bridges as vital arteries in economical and political point
of view. Management of bridges in the recent years has improved significantly. Using new methods and
technology, such as wireless and fiber optic sensor and remote management changed infrastructures
management significantly.
In this paper, fast assessing of mega bridges in Rudbar has been studied. Using visual inspection as the
main source of relevant data to carry out the condition assessment is usual methods for structural health
monitoring (SHM). Today's most of decisions are based on visual inspection of projects that give good
information and vision to engineer for choosing the best method for maintenance and rehabilitation of mega
structures. Using some new methods such as signal processing, image processing, neural network and fuzzy
logic etc can help to have a better assessing for bridges. Sometimes a combination of these methods is the
best one and engineer chooses the method based on inspection.
1
Corresponding author. Tel.: + (989124672407); fax: + (981313220057).
E-mail address: lima.iust@gmail.com
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The use of non-destructive testing (NDT), monitoring and health monitoring in condition assessment of
bridge are increased significantly [1].
2. Seismic activity of Guilan province
The Manjil (a city in Guilan province) earthquake of 20 June 1990 (Ms=7.7 Richter) strongly shocked
the northwestern Iranian territory that caused many destructions and human casualties. An estimated 35.000
people lost their lives and more than 300.000 were left homeless. The earthquake ground shaking caused
enormous destruction of unreinforced Structures (Fig1, 2). The most parts of the imprinted great area were of
western high Alborz and Tarom district. The amount of damage in rural areas was very extensive that
resulting in the destruction of about 1100 villages [2]. Seismic hazard assessment of Guilan Province
including Manjil in Iran has been studied and shown, with respect to historical earthquakes in the region of
Guilan province and existing active faults like Manjil-Rudbar, this region has high seismic potential [3] and
liquefaction potential [4].
Fig1: Bala Bala bridge, and some evidence about probability of liquifaction around piers
Fig2: liquefied sands that have laterally moved toward the Shahroud River in Bala Bala bridge[4]
Fig3: Horizontal seismic hazard (PGA over bedrock) map of Guilan province using logic tree for 475 year return period
(left), for 2475 year return period (right) [3]
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Table 1: Main faults of Guilan Province [5]
No
Name
1
2
3
4
5
Manjil-Rudbar
Talesh
Fouman
North Alborz
Khazar(Alborz)
6
7
Javaher Dasht
North Qazvin
Fault Length
(km)
152
75
60
300
600
74
60
Fig4: Active faults of Guilan province and the city of Rudbar [5]
Based on Horizontal seismic hazard (PGA over bedrock) map of Guilan province for 475 and 2475-year
return period, Rudbar and Manjil have a high seismic hazard (Fig3). Having 152 km fault in Manjil-Rudbar
is show high seismic potential of this region (Fig4 and Table1). Beside high seismic activity and hazard,
some cases of liquefaction (Fig5) have been reported during Manjil earthquake 1990[4].
Fig5: Map of Bala-Bala region near Loushan and liquefaction regions in Manjil earthquake 1990[4]
3. SHM of concrete bridges:
In this research, six big bridges in Rudbar and Manjil region has studied and health of all-important part
of structural members are investigated and based on the existing condition, a SHM score allocated to each of
bridge. Six important parameter for SHM are as deck, abutment, river engineering, middle piers, wall for
water conduct. The corrosion, water scour, deformed expansion joint rubber, crack existing, etc, that has
important role in performance of a bridge are included in this research. The details of selected bridges are as
table 2. All of data explored during annually visual inspection that has been done in road and transportation
office of Guilan province.
Table 2: Name and details of selected concrete bridges in SHM study
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Number
Name of Bridge
Total Length(Meter)
1
2
3
4
5
6
Vali Abad old bridge
Bala Bala Bridge
Totkabon Bridge
Shahroud Bridge
Vali Asr Bridge
Dark Dam Bridge
180
690
450
285
312
270
Total Width of
Deck(Meter)
13.3
10.40
9.5
28
10.5
25
Number of span
6
23
15
7
13
12
A visual method is used for SHM of these bridges and assumptions are as table 3:
Table3: SHM score and determine the condition of bridge's health
Total health score
0-25
25-50
50-75
Bridge condition
Bridge is out of service and traffic must be stopped
Traffic is limited and an immediately rehabilitation should be done
Bridge needs essential repair
75-90
Bridge needs rehabilitation
90-100
Bridge is in good condition and just need to maintenance
Based on existing condition of bridges the results of SHM are summarized in table 4.
Table4: SHM score and determine the condition of bridges
Inspected Member
Bala Bala Bridge
Totkabon Bridge
Shahroud Bridge
Vali Asr Bridge
Dark Dam Bridge
1
2
Deck
Abutments
20
30
23
36
20.2
33.3
12.9
33.0
20.0
29.4
25.0
34.0
18.6
30.0
20.0
30.0
3
Middle Piers
35
35
32.4
33.7
24.1
35.0
35.0
35.0
4
5
Water conduct wall
9
-
-
-
8.6
-
9.0
9.0
Restrain
1
1
0.9
0.8
0.9
1.0
1.0
1.0
6
River engineering
5
5
4.4
4.6
3.7
4.9
5.0
5.0
With
conduct
wall
Without
conduct
wall
No
Vali Abad old bridge
Maximum
health score
based on
visual
inspection
Fig6: Total SHM score of concrete bridges (out of 100) in Rudbar region (included Manjil city)
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Fig7: Water scour in Totkabon Bridge (lacking of casing) and exposure of rebar
Figure 6 shows that Bala Bala and Totkabon Bridge are needed to rehabilitation method and SHM score of middle piers
and water scour of them caused some damages. In addition Vali Abad Old Bridge needs more attention to preserve its
structural function. Exposures of rebar in middle piers are shown in figure7.some of methods for maintenance of these
bridges are: replace short drainage pipe with some longer pipe to conduct the surface water lower than pier cap and
deck. Adding some casing protection shield in abutment, embankment and middle piers that exposed to river water
current will help to prevention of water scour and landslide in those areas. Retrofitting of damaged area with some new
method such as fiber reinforce polymer (FRP), steel jacket and etc can help to structure for sustaining the loads during
disasters.
4. Conclusion
Lifelines and infrastructure have an important role in every country and several thousand dollars have been
paid to maintenance and rehabilitation of infrastructures annually. Iran is located in a seismic prone region and in
every year, several earthquakes happen that cause severe damages. Seismic hazard assessment of Guilan Province
including Manjil in Iran showed a high seismic potential in this region. In this paper, a SHM study of six
concrete bridges based on visual inspection in Rudbar region that included Manjil city has been done and it showed that
Bala Bala and Totkabon bridges needed to care and rehabilitate. Some suggestions for rehabilitation of these bridges are
replacing short drainage pipe with some longer pipe to conduct the surface water lower than pier cap and deck.
Furthermore, adding some casing protection shield in abutment, embankment and middle piers that exposed to river
water current will help to prevention of water scour and landslide in those areas.
5. References
[1] S.K. Thakkar, Goutam Ghosh and Yogendra Singh,Structural damage identification and health monitoring and
damage identification of bridges, Advances in Bridge Engineering, March 24 - 25, 2006
[2] Mohsen Sartipi,Natural Disasters and Diagnosis of Man-made Factors the Cases of Manjil and Bam,
Environmental Sciences, 12 ,59-66, Summer 2006
[3] G.Ghodrati Amiri , S.A.razavian Ameri , Seismic hazard Assessment of Guilan province including Manjil in
Iran,14th world conference on Earthquake Engineering, October 12-17, Beijing, China, 2008
[4] M. K. Ycgian, V. G. Ghahmman, M. A. A. Nogole-Sadat, and H, Daraie, Liquifaction during the 1990 Maanjil I:
case history data, Bulletin of the Seismological of America, Vol,85,1995
[5] IIEES, International Institute of Earthquake Engineering & Seismology, http://www.iiees.ac.ir/.
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