Affiliations: Structural and Geotechnical Dynamics Lab StreGa,
Department SAVA, University of Molise, School of Engineering, Via Duca degli
Abruzzi, 86039 Termoli, Italy | Department of Structural Engineering, University of
Naples "Federico II", Via Claudio 21, 80125 Naples, Italy
Abstract: Experimental estimation of damping is currently not a
comprehensively solved problem. Although modal frequencies and mode shapes can
be measured confidently and quite easily by means of dynamic tests on civil
structures, an accurate identification of damping ratios needs further
development. Experimental values can be characterized by large error bounds
mainly because damping is strongly influenced by the magnitude of the dynamic
response of a structure. In this paper, the main issues concerning
identification of modal damping ratios are discussed in order to define methods
for their reliable estimation, to reduce uncertainties and characterize error
bounds. According to this aim, a procedure for optimized modal parameter
estimation via Stochastic Subspace Identification is also proposed. Then data
collected from an extensive literature review are analyzed depending on the
type of structure in order to point out the main factors affecting damping.
Moreover, a comparison with provisions about structural damping given in
National and International seismic codes for structural design of civil
structures is reported. This process demonstrates that the development of a
damping database based on homogeneous and reliable estimates is required for
calibration of predictive formulations to be used in the framework of
performance-based seismic design.
