Identification of a Maximum Softening Damage Indicator of RC-Structures Using Time-Frequency Techniques

This paper considers estimation of the Maximum Damage Indicator (MSDI) by using time-frequency system identification techniques for an RC-structure subjected to earthquake excitation. The MSDI relates the global damage state of the RC-structure to the relative decrease of the fundamental eigenfrequency in an equivalent linear model with slowly varying stiffness properties, displaying the combined damage effects of the maximum displacement ductility of the structure during exstreme plastic deformations and the stiffness deterioration in the elastic regime, also called final softening. In order to use the MSDI, robust estimates of the fundamental eigenfrequency of the equivalent linear structure are required