Structural Vibration Monitoring System for the Bosporus Suspension Bridges

Abstract

The study will describe the structural health monitoring system installed on the Bosporus Suspension Bridge. The bridge, commissioned in 1973, has a main span of 1074 m. The bridge deck has a total width of 33.4m. The deck is supported by four steel towers of 165 m height. The ambient vibrations of the Bosporus Bridge has been investigated. For the structural health monitoring system, the following sensors are installed in the system: One wind speed transducer at the mid-span; Four vertical, three transverse and two longitudinal acceleration transducers at the mid-span, one-fourth of the span and at the top of Beylerbeyi tower; Four seismometers at the foundation of towers and cable anchorages; Two relative displacement transducers at the Ortaköy joint and; One optical displacement transducer at the mid-span. The response of these transducers, digitized at the source is transferred to central recording/monitoring system located at the control building. The triggering is based on the exceedance of the appropriately set threshold levels.

A new vibration monitoring system has been designed for Fatih Sultan Mehmet Suspension Bridge. Various techniques will be studied to optimally place 32 triaxial solid-state acceleration monitoring sensors. The data, digitized at the source will be monitored by two parallel PC systems operating under the “SEISLOG“ data acquisition software, developed by University of Bergen. Damage to bridge will be inferred from the response of distributed sensors (vibrational data) and the analytical modeling of the structure through the use of system identification techniques. The structural models or properties (generally modal parameters) will be systematically determined by using the measured response and, if available, the corresponding excitation (ambient or transient) of the bridge through an integrated approach of experimental, analytical and computational techniques.