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This paper presents the design, construction and structural response of a laboratory FRP footbridge. Pultruded elements, Glass-FRP profiles and Carbon-FRP strips, comprise the 10 m long simply supported structure, which linear mass is only 80 kg/m approximately. A value of L/200 (L being the length of the span) was the limit adopted for the long-term deflection at mid-span, and verifications at Ultimate Limit State were carried out according to the recommendations of the FRP manufacturer and the European Guideline to design FRP Structures. To construct the bridge, the following phases were completed: (i) bonding CFRP strips to the GFRP stringers, (ii) connecting the FRP elements, (iii) casting concrete at the support regions, and (iv) installing the deck. Once the construction finished, an experimental static and dynamic campaign was performed to assess the bridge structural behavior. As expected from the design stage, excessive vertical vibrations under different pedestrian actions (walking and bouncing) were measured.

The finite element model (FE) updating is a calibration method that allows minimizing the discrepancies between the numerical and experimental modal parameters. As result, a more accurate FE model is obtained and the structural analysis can represent the real behaviour of the structure. However, it is a high computational cost process. To overcome this issue, alternative techniques have been developed. This study focuses on the use of the unscented Kalman filter (UKF), which is a local optimization algorithm based on statistical estimation of parameters taken into account the measurements. The dome of a real chapel is considered as benchmark structure. A FE model is updated applying two different algorithms: (i) the multi-objective genetic algorithm and (ii) a hybrid unscented Kalman filter-multi-objective genetic algorithm (UKF-MGA). Finally, a discussion of the results will be presented to compare the performance of both algorithms.