Namhae Bridge
 

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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