Procedures for structural damage identification

AMANI, MARTA; RIERA, JORGE; CURADELLI, OSCAR

San Diego, California.

Conferencia; 4th World Conference on Structural Control and Monitoring; 2006

Int. Association for Structural Control and Monitoring and University of California

The practical difficulties presented by forced vibration testing of large structures, such as tall buildings, dams or bridges, led to great interest in structural monitoring through ambient vibrations, which usually allows the identification of modal properties, natural frequencies, damping and modal shapes. Changes in these modal properties constitute an indication of structural damage, which can be assessed on the basis of experimental evidence in connection with the specific structural type and material. In previous contributions, the authors describe an approach to determine the socalled damage damping and stiffness matrices, which are essential in the identification process of the location and intensity of damage (Amani et al, 2005). No restrictions are introduced on the damping matrix, except for the viscous nature of dissipative forces and the linear behavior of the system. The latter are however always applicable assumptions, on account of the stationarity and low amplitude of the monitored vibrations. In fact, the approach requires ambient vibration data records of all relevant coordinates used in the structural model, which are processed employing the SSI-Cov method in conjunction with a modal analysis scheme developed by the authors, as described in the first part of the paper. Since attention has been recently called to the influence on modal parameters of ambient or background factors, such as temperature, humidity and solar radiation, in the second part of the paper an approach is suggested to filter out those influences, in such a way that the properties experimentally determined correspond to reference ambient conditions. The evolution of  damping with damage in steel and concrete structures are also areas that, in spite of their importance in damage assessment, remain largely unexplored. Both issues appear to be essential in the development of successful tools to detect damage in large structural systems through the monitoring of ambient vibrations.et al, 2005). No restrictions are introduced on the damping matrix, except for the viscous nature of dissipative forces and the linear behavior of the system. The latter are however always applicable assumptions, on account of the stationarity and low amplitude of the monitored vibrations. In fact, the approach requires ambient vibration data records of all relevant coordinates used in the structural model, which are processed employing the SSI-Cov method in conjunction with a modal analysis scheme developed by the authors, as described in the first part of the paper. Since attention has been recently called to the influence on modal parameters of ambient or background factors, such as temperature, humidity and solar radiation, in the second part of the paper an approach is suggested to filter out those influences, in such a way that the properties experimentally determined correspond to reference ambient conditions. The evolution of  damping with damage in steel and concrete structures are also areas that, in spite of their importance in damage assessment, remain largely unexplored. Both issues appear to be essential in the development of successful tools to detect damage in large structural systems through the monitoring of ambient vibrations.