Structural health monitoring: Early warning system for Bosporus Bridge
Mustafa Erdik, Nurdan Apaydyn
Bogazici University, Dept. Of Earthquake Engineering, Kandilli Rasathanesi, 81220 Gengelkoy, Istanbul, Turkey.
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Structural health monitoring can be defined as the diagnostic monitoring of the integrity or condition of a structure. The intent is to detect and locate damage or degradation in structural components and to provide this information quickly and in a form easily understood by the operators or occupants of the structure. The damage may result from fatigue, large earthquake, strong winds, and explosion or vehicle impact. Early detection of damage or structural degradation prior to local failure can prevent "runaway" catastrophic failure of the system. In the event of an earthquake, the rapid detection of catastrophic failure of a strategic bridge can allow early and effective response by highway officials in rerouting traffic and defusing an otherwise difficult situation. The large physical sizes of the bridges necessitate an extensive array of different sensors and appropriate technologies for data acquisition/reduction for rational health monitoring applications. Structural health monitoring systems should also be designed for a long life under severe environmental conditions. The system should be able to automatically detect, locate and assess structural damage anywhere within the bridge system (health monitoring), and to communicate the status (alerting) to responsible authorities. At its simplest application, the threshold exceedance anywhere in the bridge is monitored and an alarm is provided if pre-set threshold levels have been exceeded. This alarm may be used to automatically divert the traffic if it indicates damage due to earthquake, explosion or impact.
The study will describe the structural health monitoring system installed on the Bogazici Suspension Bridge. The bridge, commissioned in 1973, has a main span of 1074 m. The bridge deck has a total width of 33.4 m.