Seismic Damage Assessment and Performance Levels of Reinforced Concrete Members

It has been well accepted that performance-based seismic design (PBSD) principles and procedures will be at the core of the next generation of seismic design codes. PBSD necessitates the quantitative assessment of seismic damage suffered by structures. Quantitative assessment of damage has been proved effective in controlling the earthquake-induced damage of structures, and is feasible by the use of damage models. So far the Park-Ang damage model has remained to be the most widely used one. This model, however, has the inherent deficiency referring to its convergence at upper and lower limits. In this study, a modification is proposed for the original Park-Ang damage model, eliminating its non-convergence problem at upper and lower limits. The combination coefficient of the modified model is calculated using the cyclic test results of flexure-dominant RC members from the database provided by the Pacific Earthquake Engineering Research Center and the author's own tests. An empirical formula is derived through multivariable nonlinear regression analysis to relate the coefficient with three design parameters. The comparison between the modified and original model indicates that the damage index of flexure-dominant RC members can be determined by the modified model with higher precision and smaller scatter. The damage indices at principal damage states are calculated by the modified damage model for each member in the above mentioned database. Accordingly, the performance levels of RC structural members are quantified by setting the individual limit value of damage index.