The Vasco da Gama bridge is located near Lisbon and is the second crossing of the Tejo river. Three types of test were done: Ambient vibration test, free vibration test and measurements in the stay cables. The results shown below are based on the ambient vibration test. The equipment used were 6 triaxial GeoSIG seismographs synchronized by a portable PC.
Below a series of pictures of the bridge are shown. They show it during and after construction:
The modal analysis has been performed using the Crystal Clear Stochastic Subspace Identification estimator available in the ARTeMIS Modal Pro version. Below a screen dump show the stabilization diagram obtained from one of the Test Setups. In addition, the Modal Assurance Criterion (MAC) between all the modes is shown, and reveal that the mode shapes a orthogonal.
Crystal Clear Stochastic Subspace Identification of the modes of the bridge.
Below the modes are presented. The modes has been estimated with default settings of the Crystal Clear Stochastic Subspace Identification estimator available in the ARTeMIS Modal Pro version.
Laboratory of Vibrations and Structural Monitoring of FEUP VIBEST has their own web site at: www.fe.up.pt/vibest. A detailed description of the test they did can be found in the following papers:
Cunha Á., Caetano E. and Delgado, R.
Dynamic Tests on a Large Cable-Stayed Bridge. An Efficient Approach.
Journal of Bridge Engineering, ASCE, Vol. 6, No.1, pp.54-62, 2001.
Cunha Á., Caetano E., Brincker R., Andersen P.
Identification from the Natural Response of Vasco da Gama Bridge
22nd International Modal Analysis Conference (IMAC), Dearborn, Michigan, 2004.