Seismic Risk Prioritization of Essential Hospital Buildings at Ilocos Training and Regional Medical Center Using a Composite Seismic Risk Index

Abstract

The Philippines, located along the Pacific Ring of Fire, faces frequent damaging earthquakes that threaten the operability of essential hospitals. This study assesses the seismic risk of 21 essential hospital buildings at the Ilocos Training and Regional Medical Center (ITRMC) in San Fernando City, La Union, within seismic zone 4 of the Philippine archipelago. A seismic risk index (SRI) was formulated by integrating three key components: structural vulnerability assessment utilizing a locally adopted Rapid Visual Screening (RVS) procedure based on FEMA P-154 and Philippine studies, site-specific seismic hazard evaluation applying Probabilistic Seismic Hazard Analysis (PSHA) with a point-source model, and building-level asset valuation capturing operational, societal, and cultural dimensions. The RVS scores of the hospital buildings ranged from 1.32 to 1.56, indicating uniformly low structural vulnerability. The PSHA results indicate that the peak ground acceleration (PGA) is 0.34g, which places the site in a high-hazard category. The asset value indices range from 1.69 to 8.09 and are indicative of considerable variability in the functional importance of each of the buildings. Combining these three components together forms a composite SRI. Using the composite SRI, 52.38% (11 of 21) of the buildings are classified as being at a high-risk level, 23.81% (5 of 21) at a moderate-risk level, and 23.81% (5 of 21) at a low-risk level. These results clearly identify the need to evaluate and retrofit the Pediatric Ward (B-020) and the Emergency Room (B-008), as they have the highest priority among all the buildings evaluated. The findings of this study demonstrate that combining site-specific PSHA with an asset-based SRI provides a feasible and replicable process for identifying priorities for seismic mitigation efforts in hospitals with multiple buildings.