Seismic Vulnerability Assessment of Existing RC Moment Frames using a New Stiffness Based Damage Index

Earthquakes cause a lot of damage to structures. A quantitative estimate of the amount of damage to the structure always seems quite necessary after an earthquake. For this purpose, seismic damage indices have been introduced as dimensionless quantities that can report the extent of damage using various criteria. This quantitative assessment can help make decisions about the process of improving, repairing, and strengthening structures. This paper presented a new stiffness-based damage index with simple formulation by performing pushover analysis on existing concrete models and applying the results. Using the capacity curve obtained from the pushover analysis output, this index can provide a quantitative estimate of the amount of damage to the entire structure. To validate the results, damage estimation was also performed using several reliable models such as the Park-Ang model and then compared with the proposed index results. Then, a series of theoretical suggestions were presented to address the existing weaknesses, which were implemented, and new results were obtained. Finally, the implemented reform proposals led to an improvement in the performance of the proposed index, resulting in excellent accuracy due to the simple computational process compared to the complex implementation of the Park Ang index.