Dynamic assessment of the São João Bridge structural integrity

Abstract

São João Bridge, crossing the River Douro, in Oporto, is open to traffic since 1991. It is a prestressed concrete bridge, with a main span of 250 m and a total length of 1028 m. Its structural behaviour has been monitored since construction. In 2014, a vibration-based continuous monitoring system was installed on the bridge. An integrated procedure was developed to automatically carry out the data processing and to extract the modal parameters in real time, using the Stochastic Subspace Identification technique (SSI) and cluster analysis. This paper presents the evolution of its structural health monitoring system, as well the procedure developed for the dynamic assessment of the São João Bridge. Some experimental results are presented and compared with the values predicted by a finite element model. The influence of both environmental conditions and operational factors is discussed.