Monitoring, Control and Identification of Bridges by Dynamic Methods
May 24, 2010 — May 28, 2010
Coordinators:
- Francesco Benedettini (Università dell'Aquila, Monteluco di Rojo, Italy)
- Antonino Morassi (Università di Udine, Italy)
Bridge infrastructures are one of the systems on which a large amount of economical resources is reserved in every country, both for new construction and for the programmed maintenance of the existing ones. Due to the fast increase of both ordinary and exceptional traffic loads and because of the harshness of the environmental conditions, bridge structures are deteriorating at an alarming rate. Moreover, since the main European and American highways were built around the 60’s-70’s, many important bridges have reached the critical age of 30–40 years of service at which rehabilitation and retrofit become essential. In some countries, in addition, the introduction of new national seismic codes requires the assessment of the structural safety of bridges and prediction of their residual operational life under seismic loads that, generally, are higher than the previous ones.
For these reasons, one of the most important and actual challenges in the field of civil engineering infrastructures concerns the development of health monitoring programs able to give real-time knowledge of a critical condition possibly occurring in a bridge system.
Bridge condition assessment is usually carried out by visual inspections. However, visual inspections suffer of many disadvantages. They cost significantly and, more important, many experts argued that the limitations and shortcomings associated with the subjective character of this evaluation able, in principle, to cause erroneous destination of economical resources. Non destructive dynamic methods are the ideal candidate for objective/quantitative health monitoring applications on bridges. Traditional applications of Experimental Modal Analysis are mainly based on the measurement of frequency response functions and, as a consequence, require the closure of the tested structure for its normal use. This circumstance could be too restrictive or even impossible for monitoring programs. In these cases, even if the excitation is not measured (e.g., the input is produced by the ordinary traffic or by ambient noise), modern output-only identification techniques of Operational Modal Analysis represent an effective way of operation for monitoring purposes since they can be used to estimate the dynamic parameters of a bridge without interrupting its service.
Full-scale dynamic testing provides very useful information about the structural behaviour of bridges. In fact, the calibration of an analytical model of a bridge, via structural identification techniques, gives a fundamental and quantitative understanding of the critical elements and mechanisms that deserve the most attention in modelling, such as mechanisms of flexibility, energy dissipation and inertia. The resulting calibrated model can be used to reliably evaluate the serviceability and safety limit states of a bridge or it can be adopted as the starting point of a health monitoring program.
The purpose of the course is to present an updated state-of-the-art overview of the dynamic methods for monitoring, control and identification of bridges, including modern experimental techniques, advanced computational methods and analysis of the theoretical aspects which are important in practical applications. Several experimental applications to real life situations concerning full-scale bridges will be treated in the lectures.
The course is addressed to PhD students, doctoral and postdoctoral researchers working in the area of civil and mechanic engineering.
Keywords: Structures, Experimental Mechanics, Vibrations of Solids and Structures, Material Parameters Identification, Computational Techniques