ARMAV: Auto Regressive Moving Average Vectors

A general overview of the ARMAV technique can be found in many recent papers published on different journals and conference proceedings. This technique has already been applied in many circumstances, for bridges, dams, offshore plants and civil buildings.
In many of the these cases, the excitation is due to wind, flowing traffic or ground micro movements, so that the exciting force is unmeasurable.
Considering that signal stationarity is rarely respected over a relatively long acquisition period (i.e. typical record lengths used in bridge testing), shorter data time spans can be adopted for the ARMAV analysis, being the method well suited and properly working even over very short data (i.e. hundreds of data points).

WET: Wavelet Estimation Technique

The Wavelet representation the time-frequency domain results very useful when the signal is a free response or a Random Decrement time history of a bridge recorded output.
The time frequency maps allow to follow the decay of each vibration mode of the structure, giving the envelope of the free response.
The damping coefficients, which are usually badly estimated, can be obtained with a greater accuracy.

CVA-BR: Canonical Variate Analysis - Balanced Realization

This technique takes origin from the control system theory and is based on a stochastic state space system expression. The CVA method has demonstrated very efficient when signals are very noisy and many modes of vibration appear just detectable or highly coupled. The method allows calculation of system parameters and measurement noise.
The BR method is basically the same as the CVA method apart for some simplification introduced.

Simulations

Analytical simulations of vehicle-bridge interaction

An analytical study of the dynamic behaviour of multi-span bridges can be useful to forecast results of a Finite Element model or the experimental modal analysis.
The ultimate goal consists in predicting the bridge dynamics under a travelling vehicle, whose characteristics can be settled by the operator.
Furthermore, since experimental measurements are pickup along the edges of the deck and several modes may be excited, accurate modes shapes and frequencies must be identified in advance. A typical error source in Bridge dynamics is in fact represented by the low number of measurement points, and consequent misunderstandings in terms of identification.

Recent publications

E. Bonisoli, A. Fasana, L. Garibaldi, S. Marchesiello, "Sensitivity analysis and damage location over the z24 bridge", Structural Health Monitoring, Cachan, France, 2002.

L. Garibaldi, S. Marchesiello, A. Fasana, E. Giorcelli, S. Sorrentino, D. Sabia, " Recent advances in identification and fault detection on bridge structures", Surveillance4 - Compiègne France - October 16-18, 2001.

L. Garibaldi, A. Fasana, E. Giorcelli, D. Sabia, " Z24 Bridge Dynamic Analysis by Time Domain Methods", IMAC-XIX, Kissimmee (Florida), USA, February 5-8, 2001

A. Fasana, L. Garibaldi, S. Marchesiello, D. Sabia, "Identificazione dinamica di ponti eccitati da traffico stradale", Conferenza MATLAB, Bologna, Italia, 8-9 febbraio 2000.

L. Garibaldi, E. Giorcelli, S. Marchesiello, M. Ruzzene, "CVA-BR against ARMAV: comparison over real data from an ambient noise excited bridge", DAMAS99, Dublin, 28-30 June 1999.

L. Garibaldi, S. Marchesiello and D.J. Gorman, "Bridge dynamics misinterpretations due to low spatial resolution and closeness of frequencies", DAMAS99, Dublin, 28-30 June 1999.

S. Marchesiello, L. Garibaldi, B. Piombo, A. Fasana, "Dynamics of multi-span continuous straight bridges subject to multi-degrees of freedom moving vehicle excitation", Journal of Sound and Vibrations, Vol. 224 (3), 1999, pp.241-261.

A. Fasana, L. Garibaldi, E. Giorcelli, S. Marchesiello, M. Ruzzene, “Comparison between three identification techniques of a road bridge dynamic test”, Non Destructive Evaluation of Bridges and Highway, SPIE Conference, Newport Beach (California), USA, 3 - 5 Marzo 1999.

A. Fasana, L. Garibaldi, E. Giorcelli, S. Marchesiello, M. Ruzzene, “A road bridge dynamic response analysis by wavelet and other estimation techniques”, XVII IMAC, Orlando (Florida), USA, 8-11 Febbraio 1999.

A. Fasana, L. Garibaldi, E. Giorcelli, S. Marchesiello, M. Ruzzene, “Evaluation of road bridge dynamic response to ambient excitation by wavelet and other estimation techniques”, 3ème Conference International, Methodes de surveillance et techniques de diagnostic acoustiques et vibratoires, Senlis, France, 13-15 October 1998.

E. Giorcelli, L. Garibaldi, B. Piombo, "ARMAV techniques for traffic excited bridges", ASME Journal of Vibration and Acoustics, July 1998, pp. 713-718.

M. Ruzzene, L. Garibaldi, A. Fasana, B. Piombo, "Identification of nonlinear damping mechanisms using the wavelet transform", Méchanique Industrielle et Materiaux, Vol. 51(2), Giugno 1998.