Paolo Franchetti

Nonlinear Damping Identification in Precast Prestressed Reinforced Concrete Beams

This article presents a damage detection method for prestressed reinforced concrete (PRC) ele- ments based on free vibration tests and nonlinear damp- ing identification. Integrated static and dynamic exper- iments were carried out on three precast PRC beam specimens. The static loading induced different levels of damage to the beams. At each damage level, impul- sive loading was applied to the beams and the free vi- bration response was measured. The dynamic response data were processed using different methods including the multi-input multi-output (MIMO) curve fitting and the Hilbert transform techniques. A strong correlation is observed between the level of concrete damage (cracks) and the amount of nonlinear energy dissipation that can be modeled by means of quadratic damping. The non- linear damping can be extracted from the free vibration response for each vibration mode. The proposed method is suited for quality control when manufacturing precast PRC members, and can be further extended for in situ detection of damage in concrete structures under ambi- ent vibration.

Structural investigations and analyses for the conservation of the ‘Arsenale’ of Venice

Abstract Systematic interventions are being planned and progressively designed on most buildings of the Arsenale of Venice, the Venetian republic’s shipyard, a very large complex of docks and sheds of peculiar construction characteristics. These renovation interventions are required in view of new uses for the revitalizing of that area, which is currently almost completely neglected. In the paper, after a general presentation of the main properties and of the most relevant deterioration phenomena of the principal parts of the monumental area, the methodology that is being used for the structural diagnosis, for the implementation of guidelines for the future interventions and for the maintenance of the restored conditions are presented. Some preliminary results, given by experimental tests performed both in situ and in laboratory on materials and structural elements, and by FE simulations, are discussed.