Among all civil engineering structures, bridges & tunnels are two of the leading types that should be monitored by sensors due to their critical fatigue and creep behavior. Especially natural events such as earthquakes, floods, storms increase the importance of monitoring. A number of different types of instruments and sensors should be combined in health monitoring of railway/highway bridges, tunnels, tube crossings and subways. Although customization has a big importance in a specific health monitoring instrumentation project of a bridge or tunnel, accelerometers, strain/crack gauges, tilt, wind and temperature sensors are the most generally preferred sensors.

1. A Real-Time Instrumentation
Approach for Structural Health
Monitoring of Bridges
Sarp Dinçer, Civil and Structural Engineer(M.Sc.), Teknik Destek Grubu
Eren Aydın, Technical Coordinator, Teknik Destek Grubu
Himmet Gencer, Software Developer, Teknik Destek Grubu
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

2. Scope: This study is limited to the instrumentation part of SHM, rather
than further analysis aspects form CE point of view.
History of civil engineering is full of examples of sudden and unexpected
failures of bridges and tunnels
Çaycuma, Turkey, 2012
61 years old
Tacoma Narrows Bridge, 1940
4 months old
A Real-Time Instrumentation Approach for Structural Health Monitoring of Bridges. Proceedings of the Istanbul Bridge Conference, 2014
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

3. At least 3 theories are still available for the collapse of Tacoma Bridge,
and neither one has been agreed upon yet
A Real-Time Instrumentation Approach for Structural Health Monitoring of Bridges. Proceedings of the Istanbul Bridge Conference, 2014
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

4. Primary Causes of Failure for Bridges and Tunnels
BRIDGES
Fatigue
Reduction of Rigidity
due to Aging
TUNNELS
Creep
Huge Static Loads
during Lifetime
Why should we monitor these structures?
To prevent LIFE LOSS To prevent ECONOMIC LOSS To learn more about the BEHAVIOR
Either;
-We will wait for the structure to choose the time for sudden collapse (Disaster)
-Or, we will collapse it down after a certain period of time and construct a new one (Waste of time and Money)
-Or we will monitor them, and decide the best time and components to repair, maintain and rehabilitate
A Real-Time Instrumentation Approach for Structural Health Monitoring of Bridges. Proceedings of the Istanbul Bridge Conference, 2014
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

5. All the instrumentation proposed in this study is based on 7/24 real
time monitoring
Characteristic of Instrumentation and Sensors
STATIC + DYNAMIC
A combined approach is being proposed
Sensors
Cabling +
Wireless
Sync
Digitizer +
Data
Center
Monitoring
Software
Real-Time +
Post
Analysis SW
Reports/
Feedbacks
+Warnings
The Road to Real-Time Structural Health Monitoring
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

6. Selecting the right combination of
instruments among a big batch
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

7. General Layout for the Proposed SHM Methodology
DYNAMIC PART
Based on an innovative modification of
conventional data acquisition
STATIC PART
Based on an fiber-optical solution with FBG
(fiber-bragg-grating) sensors
WHAT IS INNOVATIVE ABOUT THIS METHOD?
Combines 2 best fits for the dynamic and static
monitoring
Consolidates 2 different technologies at the
same data center, same monitoring and real-time
analysis software
Outputs a solid turn-key solution
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

8. Dynamic Instrumentation
3000
2500
2000
1500
1000
500
0
Accelerometers (Cost/Performance)
FBA
ICP / IEPE
MEMS – MET
80 100 120 140 160
USD / AXIS
PERFORMANCE (DB)
FREQUENCY RESPONSE
BANDWIDTH
Accelerometers
Operational Modal Analysis /
Ambient Vibration
Dynamic Identity
Accelerometer Selection
Noise performance
For buildings: <300-500 nano-g/√Hz
*For bridges: <10μg/√Hz
Bandwidth(at least):0.1 – 100 Hz
Range: ±2 to 3 g
-Conventional FBAs: best for long period signals, close to DC.
-MEMS/METs: also including force-feedback, best for 0.1 to 100 Hz signals.
-IEPE type piezo-electric: best for high frequency measurement
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

9. Dynamic Instrumentation
Digitizer Selection
A general rule of thumb:
24-Bit + Simultaneous Sampling(1kHz) + >120 dB
What is proposed extra in this approach?
+ Wireless GPS Based Synchronization
for each independent node
+ Low-cost & <1 micro-second resolution
+ Directly drives ADCs
+ Digital data transfer over ethernet
+ No analog cabling
TESTBOX™/e-QUAKE™
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

10. Static Instrumentation
Fiber Bragg Grating (FBG)
Monitors and Measures:
Deformations
Stress Levels
Position of Neutral Axis
Torsion
Tilt
Crack
Why Fiber?
Long spans
Different installation
opportunities
Static measurement
Multiplexing
EMI/RFI Immunity
Cost optimization
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

11. Overview of the Combined Approach
WHY?
Both parts are not fiber?
 High cost for simultaneous sampling at dynamic speeds especially when the number of
nodes increase
 Fiber accelerometers are not as efficient as low-cost MEMS-MET accelerometers
 Hard to maintain a full synchronization for operational modal analysis as the no of nodes
increase
Both parts are not conventional?
 FBG strain gauges are the best fit having a number of installation choices
 Cost decreases as the number of nodes increase
 Conventional strain gauges are not as durable as fiber sensors
 Conventional strain gauges need protection and modification, which increases the cost
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

12. Conclusion
A well-combined mixed approach has been proposed for
Real-Time structural health monitoring of bridges
Conventional, analog instrumentation solves the dynamic
monitoring, including acceleration and dynamic
identification.
This conventional dynamic part includes innovative solutions
inside such as wireless GPS based time synchronization
Fiber sensors solves the static monitoring, including
deformation, stress, neutral axis watch, torsion, tilt and crack
watch.
Data center is capable of handling both parts smoothly.
Real-time calculations and analysis is carried out by a
integrated software both separately and sometimes
considering and double checking the static and dynamic
measurements together.
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

13. A Real-Time Instrumentation
Approach for Structural Health
Monitoring of Bridges
Sarp Dinçer, Civil and Structural Engineer(M.Sc.), Teknik Destek Grubu
Eren Aydın, Technical Coordinator, Teknik Destek Grubu
Himmet Gencer, Software Developer, Teknik Destek Grubu
TESTBOX
Data Acquisition Systems
Manufacturer of Turkey
TESTART
Sensor & Test
Technologies
www.testart.com.tr
Thank you.
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

14. Tunnels
For tunnels, it is possible to monitor deformation and convergence by fiber optic sensors.
A solid case study for this solution was carried out by Barbosa et al. in 2009 for Rossio train tunnel in Lisbon,
Portugal.
The monitoring system was a complete solution that comprises measurements of strain and temperature with
more than 850 fiber Bragg grating sensors, data acquisition, processing, storage and easy access through a
web platform.
The used method for convergence monitoring (MEMCOT) makes it possible to determine tunnel
convergences based on strain measurements around the tunnel contour.
An optoelectronic measurement unit and optic switch are deployed at the entrance of the tunnel and
remotely connected to a server that saves and displays information to authorized users in web interface
Rossio Railway Tunnel, Lisbon Portugal
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

15. Recent Solid Experiences From Buildings
Kuzey-Güney
Doğu-Batı
EKSEN DOĞU-BATI KUZEY-GÜNEY
1.MOD
FREKANS
(Hz)
HAKİM
PERİYOT
(sn)
1.MOD
FREKANS
(Hz)
HAKİM
PERİYOT
(sn)
REF BİNASI 1,80 0,55 1,56 0,64
TEST BİNASI 1,38 0,73 1,48 0,68
DEĞİŞİMİN
ANLAMI
TEST BİNASINDA CİDDİ
RİJİTLİK KAYBI /
YUMUŞAMA
TEST BİNASINDA RİJİTLİK
KAYBI / YUMUŞAMA
DEĞİŞİM ORANI
(%)
33 6
REF
TEST
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

16. Recent Solid Experiences From Buildings
Kuzey-Güney
Doğu-Batı
EKSEN DOĞU-BATI KUZEY-GÜNEY
1.MOD (Hz) 2.MOD (Hz) 1.MOD (Hz) 2.MOD (Hz)
DURUM 1 1.824 5.608 1.562 5.210
DURUM 2 1.808 5.551 1.554 5.161
DURUM 3 1.792 5.480 1.550 5.126
EKSEN DOĞU-BATI KUZEY-GÜNEY
1.MOD
% Artış
2.MOD
% Artış
1.MOD
% Artış
2.MOD
% Artış
DURUM 1-2 0.9 1.1 0.6 1
DURUM 2-3 0.9 1.1 0.2 0.5
DURUM 1-3 1.8 2.2 0.8 1.6
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You

17. Oversampling Dynamic Range and Effective Resolution
Her 1 bit çözünürlük artışı için sinyal, 4’ün o kadar kuvveti kadar
fazla örneklenmelidir(oversample)
Örnek: 19 bit @ 4 kHz bir sistem ? @50Hz
4kHz=4w. 50 Hz 80=4w w=3.2 bit
Etkili çözünürlük(ENOB)= 19 + 3,2 = 22 bit @ 50Hz
200 Hz’de, 128 dB dinamik aralığa sahip bir veri toplama
sistemine ihtiyaç varsa:
19 bit @ 4 kHz bir sistem bunu sağlayabilir mi? 19bit→116 dB
128-116= 12 dB artış bekleniyor,
Her fazladan etkili 1 bit, 6 dB artışa denk geliyor,
12 / 6 = 2 bit artış?
4kHz=4w. 200 Hz 4w=20 w>2 bit,
Bu sistemle 200Hz’de en az 2 bit, (12 dB) artış sağlanabilir.
EĞER DOĞRU OVERSAMPLING VE DOWNSAMPLING TEKNİKLERİ
KULLANILIRSA
fos= 4w.fs
w:istenilen bit artışı,
fos: fazla örnekleme frekansı,
fs: daha yüksek çözünürlüklü elde
edilen örnekleme frekansı
BİT dB O/S
SNR(dB) = (6,02 . ENOB) + 1,76
SNR: sinyal gürültü oranı
ENOB: etkili çözünürlük
1.Welcome
2.Introduction &
Scope
3.Why to Monitor?
4.7/24 Real-Time
Monitoring
5.Solution
6.General Layout
7.Dynamic Part
8.Static Part
9.Overview
10.Conclusion
11.Thank You