Evaluation of seismic indices for identifying vulnerable reinforced concrete wall buildings in Chile

Past earthquakes have shown that reinforced concrete (RC) wall buildings are vulnerable to seismic damage. Identifying vulnerable buildings before future events enable the implementation of prevention strategies, such as retrofitting vulnerable structures. Assessing the seismic vulnerability of a large building stock is complex, and a rapid and effective evaluation is necessary to identify vulnerable buildings. Different methods have been proposed to evaluate the seismic vulnerability of buildings, ranging from complex analytical methods to simplified empirical methods that rely on the statistical treatment of observed damage after past earthquakes to calculate seismic indices. However, limited studies have been conducted to relate seismic indices to observed damage for Chilean buildings. The main objective of this research is to evaluate seismic indices to assess the seismic vulnerability of RC wall buildings using empirical data from the 2010 Maule earthquake. A database of 158 undamaged buildings and 30 damaged buildings following the 2010 Maule earthquake is considered. For each building, three capacity-based indices, two demand-based indices, and six demand-to-capacity indices are calculated. The demand-based indices are calculated using both the actual seismic demand and the seismic design demand. The ability of each seismic index to identify undamaged and damaged buildings is quantified using Receiver Operating Characteristic (ROC) analysis. Results suggest that capacity-based indices alone are not adequate to identify damaged buildings, while demand-based and demand-to-capacity based indices are more accurate at identifying damaged buildings. Although demand-based indices using seismic design demand are less accurate than those using the actual seismic demand, they remain practical when detailed seismic data is unavailable.