In the summer of 1996, the Hyundai Corporation contracted
with Kinemetrics for a real-time monitoring system
for the Namhae Bridge located in the Republic of
South Korea.
The aim of this project is to improve public safety
through the better management decisions offered by
using a state-of-the-art monitoring system.
Kinemetrics and its partners for this project; Agbabian
Associates of Pasadena, California and Batu Engineering
of Seoul, Republic of South Korea, installed the
system in the fall of 1996.
The Namhae Bridge is a suspension bridge constructed
in 1973. The physical dimensions of the bridge are:
- Total length 650 m
- Main span 400 m
- Side spans 125m each
- Width 11m
- Towers 38 m above deck surface and 60 m above
water
The scope of Kinemetrics' contract with Hyundai
Corporation included:
- Recommendation of sensor types
- Manufacturing and integration
of a 36-channel real-time monitoring system
- Design and implementation of
a communication system using fiber optic cables
- Installation of complete system
- Performance of acceptance tests,
training and on-going support
Transducers
- 12 uniaxial accelerometers
- 2 triaxial accelerometers
- 4 displacement transducers
- 10 strain gages
- 2 three-component anemometers
Data Acquisition System
The data acquisition system consists of two Kinemetrics'
Mt Whitney systems on the bridge for a total of
36 input channels. Each Mt Whitney system records
events onto its 40 MB SanDisk removable memory
card as soon as the system trigger threshold has
been exceeded. Each event is stamped to UTC time
by using a GPS receiver. In addition, each Mt Whitney
system sends a continuous data stream to the data
processing system for remote monitoring of the
structure.
Data Communication System
Two fiber optic communication cables link the data
acquisition system and the data processing system.
Data Processing System
The data processing system, installed at the control
center and located two kilometers from the bridge,
consists of a Pentium computer running Windows
95 and OASIS* software. The OASIS software provides
continuous monitoring of the structure and triggers
audible and visual alarms as soon as the exceedance
criteria have been met.
OASIS Software Offers:
- Visual display of the structure and sensor icons
on the computer screen
- Real-time, dual level alerting of damage states
including location
- Waveform display and statistics from any channel
- Remote control of data
acquisition system
The advantage of this system is that it provides
remote real-time display and alerting as well as
event-triggered recording.
Hyundai Corporation used
the system for ambient vibration monitoring and load
testing during early 1997. Strain data will be used
for fatigue studies in order to estimate the remaining
life of critical components.
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