Author's manuscript version. The final published version is available via the publisher at doi:10.1016/j.engstruct.2010.02.034. Copyright © 2010 Elsevier Ltd. All rights reserved.An ambient vibration survey of the Humber Bridge was carried out in July 2008 by a combined\ud team from the UK, Portugal and Hong Kong. The exercise had several purposes that included\ud the evaluation of current technology for instrumentation and system identification and the\ud generation of an experimental data set of modal properties to be used for validation and\ud updating of finite element models for scenario simulation and structural health monitoring. The\ud exercise was conducted as part of a project aimed at developing online diagnosis capabilities for\ud three landmark European suspension bridges.\ud Ten stand-alone triaxial acceleration recorders were deployed at locations along all three spans\ud and in all four pylons during five days of consecutive one-hour recordings. Time series\ud segments from the recorders were merged, and several operational modal analysis techniques\ud were used to analyse these data and assemble modal models representing the global behavior of\ud the bridge in all three dimensions for all components of the structure.\ud The paper describes the equipment and procedures used for the exercise, compares the\ud operational modal analysis (OMA) technology used for system identification and presents\ud modal parameters for key vibration modes of the complete structure.\ud Results obtained using three techniques: natural excitation technique/eignsystem realization\ud algorithm, stochastic subspace identification and p-LSCF, are compared among themselves and\ud with those obtained from a 1985 test of the bridge, showing few significant modal parameter\ud changes over 23 years in cases where direct comparison is possible\ud The measurement system and the much more sophisticated OMA technology used in the present\ud test show clear advantages necessary due to the compressed timescales compared to the earlier\ud exercise. Even so, the parameter estimates exhibit significant variability between different\ud methods and variations of the same method, while also varying in time and having inherent\ud variability.Engineering and Physical Sciences Research Council (EPSRC

This paper describes the dynamic tests performed on a large cable-stayed bridge, Vasco da Gama Bridge, on the basis of a nonconventional testing system, comprehending several independent accelerographs conveniently synchronized by a laptop, as well as a laser interferometry system for noncontact dynamic measurements in stay cables. This system showed to be rather portable, efficient, and accurate, leading to the creation of a very large high quality database concerning the dynamic behavior of the bridge. Subsequent processing of the data permitted accurate identification of all the significant modal parameters of interest from the aerodynamic and seismic point of view and presented a very good correlation with the corresponding values provided by the 3D numerical finite-element model previously developed at the design stage.