This paper presents a structural health monitoring system for monitoring, with reduced visual impact, one historical building structural. The system is based on fiber Bragg gratings and comprises 19 displacement sensors and 5 temperature sensors. All the sensors were custom made according to the monitoring points' characteristics. The results obtained over the first year of monitoring are presented. The objective of this work is to gather data that will bring a deeper knowledge of how this structure behaves and to help planning the recovering interventions in this historical building.

In this study, the implementation of an optical accelerometer unit based on fiber Bragg gratings, suitable to monitor structures with frequencies up to 45 Hz, is reported. The developed optical system was used to estimate the structure eigenfrequencies of a steel footbridge, with a total length of 300 m, over the Sao Pedro Creek, located at University of Aveiro Campus, in Portugal. The acceleration records measured with this solution are compared with those obtained by traditional commercial electronic devices, revealing a root-mean-square error of 2.53 x 10(-5) G.