A PROBABILISTIC ASSESSMENT OF SEISMIC DAMAGE IN DUCTILE STRUCTURES

The current practices in ductility-based earthquake design ignore the damage caused by the repeated random inelastic excursions. A ductile structure may however suffer different degrees of damage depending on the number and amplitudes of these inelastic excursions. The information about the largest response peak as available from the response spectra may not thus be enough as the higher-order peaks are likely to play an important role in the progressing damage. A probabilistic model is proposed here to estimate the damage in a structure with a given amount of ductility by using the order statistics of the higher-order peaks. The proposed formulation relates damage to the entire response process, not just to the largest response. It thus accounts for the different roles played by the total number of peaks in the process, the relative amplitudes and number of excursions, and frequency content of the response process.